Increased steaming from cone area Card 0041 (09 September 1968) Increased steaming from cone area The following information was reported in the "Daily Mirror" on 31 August 1968. " . . . the Commission on Volcanology revealed today that Taal volcano's abnormal condition still persists. Arturo Alcaraz, chief volcanologist, said steaming activity has increased considerably on the base and slopes of the cone formed in the last eruption. He also said that the steaming is very noticeable today from several areas of the 1968 lava flow in Kaygabok." Information Contacts: Boots Rous, Daily Mirror News, Quezon City, Manila. October 1968 (CSLP 47-68)Increasing seismicity and surface thermal activity Card 0107-0108 (08 October 1968) Volcanic earthquakes and intensified surface thermal activity The following report was received on 7 October 1968. The volcanology commission reported last night that Taal volcano had entered another active period that could culminate in another eruption. Seven volcanic quakes and tremors were recorded in a 24-hour period. COMVOL observers on Volcano Island also reported that there was intensified surface thermal activity, confirming that the volcano's condition was abnormal. COMVOL headquarters in Quezon City recommended that precautionary measure be taken particularly the complete evacuation of Volcano Island. Volcanologist Nazario Vasquez reported that instruments have picked up seven volcanic quakes and tremors from Taal's depths, clearly indicating its restlessness. Vasquez said surface steaming, rise of temperature readings in all ground probe holes, and other intensified activity in the main crater lake may all culminate in another eruption. Card 0113 (09 October 1968) Field and instrumental data indicate renewed activity The following report was received from the American Embassy in Manila on 8 October 1968. Signs Taal volcano resurgence plainly inferred by existing field and instrumental data. Surface activity at 1968 cone has gained momentum. Despite absence rains for last two or three days which might have brought about condensation steaming and emission sulfuric vapors very strong this morning. In addition, fresh slide scars attest volcano's restlessness as seismicity of island continued. Three more volcanic quakes picked up commissions seismograph; one 1758 on 7 October; another 1915 on 7 October, and third at 1106 on 8 October. Card 0121 (11 October 1968) Increased seismicity; fresh rockslide at 1968 eruption cone The following report was received from the American Embassy in Manila on 11 October 1968. Seismic activity again picked up rapidly. For the 24-hour period beginning 1530 on 9 October through 1530 on 10 October. A total of five volcanic quakes were recorded by the COMVOL seismograph on Volcano Island, at 1853 and 2454 on 9 October; and at 0233, 0235, and 1008 on 10 October. Field observations conducted early this morning (10 October) at the 1968 eruption cone disclosed fresh evidence of rock slide, indicating recent movement within the volcano. Chloride and sulfuric sublimate have spread almost throughout NW outer slope of cone. Card 0122 (11 October 1968) High level of seismic activity returns The following report was received from the Commission on Volcanology on 6 October 1968. Taal volcano shook more strongly the past 24 hours. The volcano is back to its high-level seismic activity, convulsing five times through Sunday morning. A quake recorded at 0933 on 6 October was big enough to have an amplitude of 17 mm. The usual amplitude of earthquakes at Taal volcano since it became restless again was 4-5 mm. Card 0130 (14 October 1968) Significant volcanic seismicity; steam emission intensifying The following report was received from the American Embassy in Manila on 14 October 1968. As of 13 October the surface activity and seismicity were both weak for the last 48 hours. As of 14 October at 1530 the four-day seismic lull was broken by eight volcanic microseisms of appreciable magnitude. Crater lake temperature was decreasing, but steam emission was intensifying, especially at the SW shoreline of the lake. Card 0138 (15 October 1968) High seismicity and surface thermal activity The following report was received from the American Embassy in Manila on 15 October 1968. Taal status as of 15 October 1530 hours. High level of seismic disturbance. Intensification of surface thermal activity. Card 0145-0146 (17 October 1968) Crater lake temperature increases 2.5° in two days The following news report was received on 17 October 1968. "The temperature of Taal volcano's main crater lake suddenly went up today (9 October) from 36.5 to 39°C, a sharp rise of 2.5°C in two days. The next heat reading, according to volcanologists here, exceeds that recorded in the same lake when Taal volcano erupted in 1966 (36.5°C) and early this year (34.2°C). This is, however, slightly lower than the heat reading of 39.6°C registered before Taal erupted in 1966. "Assistant chief volcanologist Gregorio Andal expressed fears that pressure and heat buildup from below may increase some more before the volcano erupts for the second time this year. He said, however, that a bigger blast can be reasonably expected to occur because more volcanic energy will be needed this time to throw out tons of earth and lava blocking the exit. 'Conditions similar to the 1965 eruption now exist in Kaigabok' Andal said, pointing out that smaller crater lakes in the same area in 1966 and 1967 have all been covered by earth and lava. "Volcanologist Pedro Almoradie Jr. and junior volcanologist Conrado Andal Jr. reported the new heat increase in the 1911 main crater lake this morning after making an on-the-spot observation. Almoradie said aside from the heat rise, emission of steam in the southwestern shores of the main crater lake was observed to be intermittent occurring every five to ten minutes. He also said all the steam vents facing Binintian Malaki started emitting more steam and vapor this morning. "Meanwhile, volcanic tremors from below quieted down for the past 24 hours despite the rising temperature in the main crater lake. The COMVOL said the seismic lull may only be temporary because all other conditions on the island are abnormal. Strict enforcement of precautionary measures under phase on of Operations Taal is now being observed." Information Contacts: December 1968 (CSLP 47-68)Continued seismicity through mid-December Card 0288 (13 December 1968) Minor seismicity; eruptive activity anticipated "COMVOL Bulletin 2300 hours 12 December. Anticipated second activity Taal about to commence. Small but continuing local vibrations recorded by Volcano Island seismograph. If persistent could bring expected eruptive activity." Card 0316 (15 December 1968) Continuous tremor replaced by spasmodic earthquakes on 15 December "Taal's surging volcanic pressure, which last Thursday night was manifested as continuous ground vibrations, seems to have been blocked. The continuous tremors have been replaced by spasmodic volcanic earthquakes often associated with crustal deformation. In the last 24-hour period, eleven (11) more shocks of this type were recorded in the COMVOL's seismographs. These developments suggest that the volcano's pent-up energy is trying to punch through and initiate an eruptive activity. As present indications point to a persistent pressure from below, the condition of Taal remains critical and a surface out-break of this pressure is perhaps just a matter of time." Information Contacts: October 1969 (CSLP 133-69)Eruption of ash and incandescent fragments on 29 October Card 0810 (29 October 1969) Eruption of ash and incandescent fragments on 29 October The following is from the Commission on Volcanology via the American Embassy in Manila. Taal eruptive activity commenced at 0615 on 29 October. Point of activity on upper outer southern slope of 1968 cone characterized by weak ejection ash and small fragmental materials at approximately 90-minute intervals. COMVOL visual observation during afternoon showed appreciable increase in amount ash and fragmental red hot volcanic materials and considerable enlargement in diameter of active vent. Increase in trace amplitude of harmonic tremors and explosion earthquake also noted. Night and early morning observations 30 October showed ejection of ash and fragments to heights of 600-700 feet at about 90-minute intervals. Continuing recording of harmonic tremors and observable pulsating vent flows seems to indicate vibration of lava to surface. Eruption is now violent though protracted. The following is from the Commission on Volcanology via Father Hennessey. Taal Volcano erupted at 0615 on 29 October. Ashes and fragments were ejected up to 900 feet at 90-minute intervals shooting up from a roaring vent about 5 m in diameter. During early hours of 30 October observations show sections of ash and incandescent fragments to 600-700 feet at varying but closer intervals compared to previous observations. Proportion of incandescent material noted increased since yesterday. Continuous recording of harmonic tremors and observable pulsating dense flow seems to indicate that lava vibrating to the surface. Information Contacts: American Embassy, Manila; Father Hennessey, Manila Observatory; Philippine Volcanology Commission, Manila. November 1969 (CSLP 133-69)Continued production of lava flows and ejecta; new cone on SE flank Card 0816 (05 November 1969) Erupting vent has enlarged; ejecta falling on upper slopes "Lava clots began appearing on 30 October 1969, with incandescent materials being thrown out by the erupting Taal volcano. The bits of molten rock from the surging column of lava are falling on the upper southeastern slope of the 1968 cone. "The chief volcanologist, Mr. Alcaraz, said that the coming eruption of Taal will not be of steam and ash but will be magmatic or cool lava. The volcano's pulsating magma has been surging with mounting intensity and frequency. The erupting vent has been enlarged and now measures almost 100 m in diameter. Taal's ejecta is being blown upward to a height of 1,500 feet. The lava column may surface in a few days, overflow, and fill the southeastern base of the 1968 cone. A protracted magma eruption might cover the thick lava deposits of the 1968 eruption in Kaygabok." Card 0820 (10 November 1969) New cone rapidly growing on the SE slope of the 1968 crater "Taal volcano is rapidly building a new cone southwest of Volcano Island on the southeastern slope of the 600-foot-high crater created by last year's eruption in Kaygabok. The conelet is now about 200 feet high. The cone's lava front advanced further into the 1966 collapsed lake on the Northeast. The lava front is more than 1 km long and is moving at the rate of 1 m per minute. The stream may eventually flow into Lake Taal. The lava, measured by a optical barometer, was found to be 1,160°C. Volcanologists said that harmonic tremors are getting stronger every day. The chief volcanologist, Mr. Alcaraz, said that this eruption is the second in recorded history where the volcano emitted more lava than ashes. The ejecta reached a height of 1,000 feet above the crater, which was widened to 20 m in diameter." Card 0824 (19 November 1969) Sustained and copius ejection of ash and incandescent fragments; lava flows The following is from the American Embassy in Manila. "Taal's current uninterrupted eruption entered 4th week this morning with activity still characterized by sustained and copious ejection of ash and incandescent fragmental materials at active vent of imposing terminal cone of 1968 eruption (former adventive cone but now too large for such designation). Ejecta has been primarily vertical but occasionally radial. Yesterday's ejections accompanied by large detonation sounds and blue-tinted gas. Subterminal flows at base in terminal cone continue molten rock discharge at intensified rate to adjacent area. Front advanced into lake southwest of island." The following is from J.J. Hennessey. "COMVOL reports at 0800 local time on 18 November. Evenings activity was more intense than that observed this morning. Ejecta was primarily incandescent bombs and blocks shot up vertically but at time ejected with a radial trajectory. Near 1730 a black column of ash started to burst out from a smaller vent on the inner western slope of the 1969 crater. This lasted for about one half hour. Lava extrusion continued without let up, the subterminal flow breaking out into four or five cascades over a rift formed by crushed lava near the northern base of the old 1968 cone. Discharge to Lake Taal is likewise continuous." Information Contacts: December 1969 (CSLP 133-69)Lava flows continue; new vent forms as activity shifts towards the west Card 0830 (02 December 1969) Intense steam emission continues; lava flows advance; new vent "The old eastern vent of the terminal cone belches noxious blue fumes continuously. From both the eastern and western vents a faint glow and a profuse steaming are observed. The Kaygabok and Alas-as lava fronts, fed by molten rocks flowing through tunnels underneath the crusted lava surface, continue to fan out very slowly lakewards. The easternmost lobe at Kaygabok has moved no less than 2 m in two days. "Voluminous emission of steam characterized the eruption surface manifestation as Taal's eruption entered its 27th day. Intense steam emissions were concentrated in the western vent of the terminal cone and the former crater of the 1968 cone, now covered by new pyroclastic materials deposited by the current eruption. "A new vent of the northwestern upper slope of the 1969 cone has been formed. Sustained ejection of steam, ash, and small amounts of larger incandescent volcanic materials from the new active vent have enlarged the crater and reduced the height of the terminal cone to a few meters. The spiraling brownish-grey ash clouds soar 4,000 feet, then accumulate at a higher altitude before drifting southwest. Comparatively stronger ejections are punctuated by weak and muffled roaring sounds." Card 0834 (09 December 1969) Signs that activity may shift to a new submarine vent in Lake Taal The possibility of a new eruption occurring beneath Lake Taal or near Mt. Binintiang Munti, southwest of volcano island, has increased. The shifting of the site of the volcano's activity and signs of an approaching eruption forced COMVOL to enlarge the danger area to include villages on the lake's western shore. The COMVOL said that there were indications that the volcano was nearing a "critical phase" of its activity. Observed were: 1) A noticeable upliftment of the ground in the vicinity of Binintiang Munti on volcano island; the ground rose by one foot. 2) Bubbling of lake waters on the side parallel to the southwest ridge. 3) Maximum trace of the amplitude of the harmonic tremors emanating from the volcano showed a continuing upward trend, although no surface outflow of lava has been observed. 4) Collapse of the lava front in the area of what was once Kay-gabok village, which was leveled at the height of the Taal eruption. 5) Strong mustard odor from the bubbling point discerned by volcanologists and people living near the island. At the moment, the volcano's activity was reportedly limited to the ejection of incandescent materials and ash to about 1,500 feet. Information Contacts: December 1970 (CSLP 113-70)Profuse steaming; fresh landslide noted; active rift Card 1077 (30 December 1970) Profuse steaming; fresh landslide noted; active rift "The Philippine Volcanology Commission issued the following bulletin on 29 December at 2300 GMT. COMVOL progressive evaluation of the condition of volcano Taal indicates that it has remained critically serious as visual and instrumental observations continue. COMVOL will issue the next bulletin after today's visual observation of the volcano's geologically active southwestern rift. Manila time 30 December gives COMVOL report for 29 December. An intensity 2 quake rocked Taal volcano at 0829 today and steam came out in the Kaygabok eruption site along a NE-SW rift leading to the main crater. The team issued the following bulletin. 1) Profuse steaming was noted on the NE upper slopes of the 1969 eruption cone and from a point a little to the NE. 2) A fresh landslide was noted. 3) The temperature of the main crater lake dropped by 1.5°C from yesterday's temperature. 4) The NE-SW rift passing through the main crater is active." Information Contacts: Philippine Commission on Volcanology; Director, Manila Observatory, Manila. September 1976 (NSEB 01:12)  |
| Figure 1. Index map showing the area around Taal, after Moxham (1967). Land area is shaded. |
| Figure 2. Map of Taal Island and vicinity, October 1965, after Moxham (1967). The 1965 explosion crater extends SW from I; the 1966 explosion crater formed immediately to the NW. |
2 September: Steaming increased at the 1966-70 eruption site and at the main crater. The area of steaming had expanded considerably, particularly to the SW. A fissure widened from 5 to 20 cm and lengthened from 50 to 100 m. Seismic activity was low.
3 September: An eruption of steam and ash began at about 0430 from Mt. Tabaro vent, a few meters SW of the site of 1966-70 activity. Eruptions occurred at about 4-minute intervals, producing clouds 1,500-3,000 m high. Harmonic tremor accompanied the activity. Evacuation had been completed at 0400.
4 September: Eruptive activity ceased at 0500. Renewed steam and ash emission occurred between 0900 and 0920 and again at 1300; the latter included some large fragments and produced a cloud 300-400 m high. Harmonic tremor was recorded during eruptions. Brownish ash blanketed the S half of the island to an unknown depth.
5 September: Individual eruptive bursts contained a greater proportion of ash and large fragments than those of previous days. No incandescent material or rumbling was observed. During the morning, eruption periods were longer than the repose periods separating them; by late afternoon, eruptions lasted about 3 minutes, followed by about 5 minutes of repose. Eruptions were nearly vertical with a slight southward component; the resulting clouds reached more than 2,000 m in the morning, but were limited to 300 m by strong SW winds in the afternoon. Late-afternoon rain caused steaming to intensify. Continuous harmonic tremor of 4 mm amplitude was recorded. The new vent was enlarged by coalescence with the adjacent cone.
6 September: Harmonic tremor amplitudes began to increase at 0330 to 3-10 mm. Emission of black, grayish-black, or reddish-brown ash-laden eruption clouds was continuous, accompanied by faint rumbling and occasional brief lightning flashes just above the vent. The eruption clouds, which contained some large rock fragments, averaged 200-300 m, reaching a maximum of 2,200 m in the early morning. Activity had slackened by afternoon, when maximum eruption cloud height was slightly more than 500 m, and the diameter was about 50 m. Lower ejection velocity and light wind caused much of the erupted material to collapse and form base surges at the foot of the 1966 cone. Rock fragments up to 30 cm in diameter produced dust clouds on the 1966 cone by impact and downslope rolling. By 1700, activity was still continuous, but the eruption cloud had diminished to 30 m across and less than 500 m high. Maximum harmonic tremor amplitude had declined.
7 September: Steam and ash eruptions continued, generating a 3,000-m cloud and base surges over the SW flank. Harmonic tremor was continuous and had a maximum amplitude of 5 mm. A new fissure opened, measuring 100 m x 20 cm.
8 September: After a midmorning period of quiescence, a new vent opened a few meters SW of the active vent of the past several days. Ash and larger fragments were ejected to 250 m height. Maximum harmonic tremor amplitude increased to 8 mm.
9 September: The strongest explosion of the eruption produced base surges that moved over the 1965 and 1966 craters. Harmonic tremor amplitudes rose from 5 to 9 mm shortly before the explosion, and reached a maximum of 12 mm during the explosion. By late afternoon, eruptive force had declined, but ash emission was still continuous and voluminous. Strong west winds carried the ash across Lake Taal to its E shore.
10 September: At 2331, incandescent gases and some incandescent fragments were noted for the first time, accompanied by a continuous hollow sound. Steam and ash emission continued.
11 September: Minor fountaining and incandescent ash clouds were observed. Steam and ash emission continued.
Reference. Moxham, R.M., 1967, Changes in surface temperature at Taal volcano, Philippines 1965-1966: BV, v. 31, p. 215-234.
Information Contacts: G. Andal, COMVOL, Quezon City; W. Ward, HQ 13th Air Force (PACAF); D. Shackelford, Villa Park, CA.
November 1976 (NSEB 01:14) Cite this Report
Strong, frequent eruptions with ashfall through mid-October
Activity continued through September and early October.
13 September: Voluminous quantities of steam and ash were emitted, causing ashfalls at towns up to 10 km E of the vent. Harmonic tremor was continuous. Intermittent incandescence was reported during the previous week.
14 September: Strong steam and ash eruptions continued until evening, when activity slackened.
15 September: Activity increased around 0700. Just before noon, a strong explosion ejected rock fragments 150 m above the vent and produced an 1,800-m ash. Ash fell on towns surrounding Lake Taal, up to 16 km E and N of the vent. One mm of ash fell in a 20-minute period and a strong stench of sulfur was noted at the volcano station, 4 km from the vent.
17 September: Ash fell continuously on towns east and north of Lake Taal, frequently mixing with rain to fall as mud. Heavy ashfall and sulfur fumes forced the evacuation of Taal Island, except for a skeleton staff remaining at the volcano station. Many work animals had died and many others were ill, probably because of sulfur-contaminated food and water. Harmonic tremor gradually increased in amplitude.
18 September: Ash and sulfur emission decreased slightly in the evening.
19 September: Diminished activity allowed an inspection on the vent area. The new crater formed on the first day of the eruption was steaming weakly. Most activity was from a 100-m-diameter vent within the 1965-70 cone, on which scattered impact craters a few centimeters to 0.7 m across were present up to 500 m from the vent. Harmonic tremor amplitude had declined. Ash emission weakened further in the evening, with occasional brief pauses. Ash clouds took 2-3 minutes to rise 700 m.
20 September: Continuous eruption resumed in the morning. No incandescence was observed. Harmonic tremor amplitude was unchanged. About 100 people had eruption-related diseases: asthmatic bronchitis, gastroenteritis, respiratory tract infection, sore eyes, and allergy.
21-22 September: The eruption weakened considerably.
23 September: Steam and ash emission increased in intensity, but no incandescence was observed. Harmonic tremor amplitude increased.
4 October: The eruption resumed after a "short lull." Ash clouds rose more than 2,100 m, accompanied by lightning, thunderstorms, and harmonic tremor.
5 October: Ash emission, in black to brownish clouds, increased. By afternoon, heavy ashfall, which forced cars to use their headlights, had deposited 2.5 cm of ash in one town near Lake Taal.
7 October: Continuous heavy ashfall forced the evacuation of five towns up to 16 km E and N of the vent. The eruption was accompanied by hollow sounds from within the crater and by harmonic tremor. Profuse emission of white steam was occurring from the source of the 1968 lava flow. A new step fault was noted near the summit of the vent.
8 October: Ash-laden steam clouds were ejected continuously to a height of 500-600 m, depositing ash around Lake Taal. Activity had migrated back to the elongate main vent. Harmonic tremor amplitude began to increase at 0330.
10 October: A reconnaissance at 1200 noted ejection of coarser fragments, accompanied by hollow reverberations, lightning, and thunder. Ash fell SW of the vent (most ash had previously fallen to the N and E). Ash eruption ended at 1650.
11 October: Activity resumed at 0100 with the ejection of brownish ash clouds, accompanied by harmonic tremor.
Information Contacts: Manila Times-Journal.
December 1976 (NSEB 01:15) Cite this Report
Weak steaming; larger steam plume on 30 October
By 30 October, Taal's eruption had declined to weak steaming, and harmonic tremor had ended. Harmonic tremor resumed at 1925 on 30 October and steam eruptions began at about 2130. During the early morning of 31 October, cauliflower-shaped steam clouds reaching 100 m height were observed, containing only minimal amounts of ash. This activity continued through the day, the clouds gradually decreasing in height and volume. No further activity had been reported by 16 November.
Further References. Alcaraz, A., and Datuin, R., 1977, Notes on Taal volcano prognostics: Journal of the Geological Society of the Philippines, v. 31, no. 2, p. 18-20.
Andal, G.A., and Aguila, L.G., 1977, Prognostic criteria of the 1976 eruption of Taal volcano: COMVOL Letter, v. 9, no. 1-2, p. 1-6.
Information Contacts: Manila Times-Journal.
October 1977 (NSEB 02:10) Cite this Report
Weak phreatic eruption with harmonic tremor
A weak phreatic eruption from the NE portion of the 1976 crater began at 1515 on 3 October, and had ended by 1400 the next day. Brownish to grayish basaltic ash clouds initially rose 300 m, and reached a maximum height of 500 m after a few hours. Activity then gradually declined to strong steaming. The eruption was accompanied by harmonic tremor. Residents of Taal Island were evacuated, and had not returned by late October because of the possibility of renewed activity.
Information Contacts: G. Andal, COMVOL, Quezon City.
November 1977 (NSEB 02:11) Cite this Report
Ejection of voluminous ash-laden steam clouds on 9 November
Taal ejected voluminous ash-laden steam clouds at 1200 on 9 November. The clouds, similar to those of 3 October, rose about 250 m before being blown toward the mainland by a moderately strong NE wind. Ground probe temperatures have increased, and harmonic tremor continued at about the same amplitude. Initial evacuation procedures remained in effect.
Information Contacts: G. Andal, COMVOL, Quezon City.
February 1978 (SEAN 03:02) Cite this Report
Harmonic tremor continues, but no eruption
"The renewed activity of Taal on 9 November resulted in the formation of a circular conelet protruding a few meters from the floor of the elongated 1976 crater. Voluminous ash-laden clouds rose to a height of 500 m with a roaring sound audible on the lakeshore. Bluish fumes were emitted from the NE inner wall of the 1976 crater. Eruptive activity ended by the early morning of 12 November, but volcanic tremor of varying amplitude continued. Tremor with a maximum double amplitude was recorded at 2210 on 24 November and at 0504 on 25 November. The initial evacuation procedure remained in effect in late January."
Further References. Ruelo, H.B., 1983, Morphology and crater development of the Mt. Tabaro eruption site, Taal volcano, Philippines: Philippine Journal of Volcanology, v. 1, no. 2, p. 19-68.
Wolfe, J.A., 1980, Eruptions of Taal volcano 1976-1977: EOS, v. 61, p. 57-58.
Information Contacts: G. Andal, COMVOL, Quezon City.
October 1987 (SEAN 12:10) Cite this Report
Increase in recorded earthquakes; minor deformation
"Recorded earthquakes began increasing 30 October. A maximum of 19 events/day was recorded on 31 October; 5 of the events were felt by residents of Agoncillo, 10.7 km SW of the crater on the W shore of Taal Lake (figure 3). The events were recorded but not felt on the volcano island, the site of historic eruptions in the Taal Caldera. Some residents of Agoncillo also reported rumbling sounds accompanying the earthquakes. Isolated reports of sulfurous stench were unconfirmed. Many residents of Agoncillo and nearby villages described the quakes as having prominent vertical movements, similar to those prior to the 1965 eruption, prompting a few families to immediately evacuate to adjacent villages. These areas were among those devastated during the 1965 phreatic explosion.
| Figure 3. Map of crater lake and vicinity, after Land Use of Taal Volcano and Environs, PHIVOLCS, 1:50,000. |
"Events on 6 November had epicenters on Manalao Point on the W shore of Taal Lake and across the lake from the 1965-77 eruption site (Mt. Tabaro; figure 3). The earthquakes had depths of 6.4 km and suggested ground fracturing beneath the caldera.
"Thermal conditions and steam emissions of the main crater lake and the 1965-77 eruption site remained within normal levels. However, the water-tube tiltmeter on the island indicated a slight inflation-deflation episode of the main crater 20 April-28 October, with the pre-inflation position now being occupied. Likewise, thermal areas near the epicenter have remained unchanged. Lake-level monitoring stations around Taal Lake, some installed only last July, indicate some warping along the lakeshore, a condition that cannot yet be related to volcanic activity.
"PHIVOLCS had installed additional seismic and ground deformation stations to monitor the events. Local authorities were informed and were prepared for any contingencies."
Information Contacts: PHIVOLCS.
December 1987 (SEAN 12:12) Cite this Report
Seismicity abates; thermal activity normal
Seismic activity ... has abated and few local events have been recorded since 14 November. Thermal and steaming conditions remained unchanged from normal levels. Lake level monitoring showed some subsidence (about 10 cm) of the SW shores of Taal Lake, which face the 1965-77 eruption site on the volcano island. Residents who fled during the crisis have returned to their homes. PHIVOLCS established 3 EDM lines, 1 dry tilt network, and one precise leveling line on the island's SW sector near the 1965-77 eruption site. Volcanologists had also re-occupied old seismic stations on the SE part of the volcano island.
Information Contacts: PHIVOLCS.
August 1988 (SEAN 13:08) Cite this Report
Seismicity and slight inflation
During a two-week period in mid-August, several small, high-frequency events with average maximum double amplitudes of 2 mm were detected at the Pira-Piraso seismograph station. From 16-22 August, 11 high-frequency events were recorded. Slight inflation was detected by the water tube tiltmeter at the station. Weak steaming continued at the 1965 eruption site. Ground-probe hole temperatures were within normal limits and the lake level remained unchanged.
Information Contacts: PHIVOLCS.
October 1989 (SEAN 14:10) Cite this Report
Increased seismicity; main crater inflation
Since July, seismicity at Taal has increased from background level to a maximum of 126 volcanic earthquakes/week, with at least three events recorded daily. Epicenters clustered around the main crater and about 2 km NE (near Pinagulbuan), migrating from 9 to 5 km depth, 18 August-2 October. Precise leveling and dry tilt surveys suggest inflation of the main crater and the 1965 eruption site, while a water tube tiltmeter has measured inflation of the main crater area since May.
Information Contacts: PHIVOLCS.
March 1991 (BGVN 16:03) Cite this Report
Increased shallow seismicity and felt earthquakes; more than 1,000 evacuated
Seismologists and area residents noticed a significant increase in seismicity beginning on 12 March (figure 4). High-frequency earthquakes were recorded each day (to 64 on 25 March), of which several/day were felt (intensities to IV). Seismicity was centered under the E side of Volcano Island, at depths of 2-5 km.
| Figure 4. Daily number of recorded earthquakes at Taal, 10 March-13 May 1991. Courtesy of PHIVOLCS. |
Monitoring of the volcano's main crater lake (1.0 x 1.4 km) revealed that the acidity of the lake water has fluctuated considerably, between pH 2.3 and 3.8. Possible slight increases in water temperature (stable at 30°C in mid-April), a change in water color (from light yellowish-green to dark green), and more vigorous bubbling were also noted.
On 1 April, President Aquino ordered the evacuation of the roughly 4,000 people who live on Volcano Island, and more than 1,000 residents (mostly women and children) had left by the following day. Seismicity remained at elevated levels, and the island was partially evacuated as of mid-April.
Information Contacts: R. Punongbayan, PHIVOLCS; Chris Newhall, USGS Reston; Manila Bulletin, Manila, Philippines.
April 1991 (BGVN 16:04) Cite this Report
Continued seismicity and changes to crater lake
High seismicity continued as of early May, with the daily number of earthquakes varying from 15 to 30 (figure 4). Felt earthquakes reached intensity IV. Acidity and chloride content of the volcano's crater lake continued to fluctuate, ranging from 2.4-2.8 and 9,630-11,720 ppm, respectively. Lake temperature increased slightly from 30° to 31°C, and lake level rose by 4 cm.
On 26 April, strong bubbling and increased steaming were observed in the N sector of the crater and at the base of the wall. Geysering, to 1.2 m height, was also noted near the NNE shore of the lake, where water temperatures of 99°C were measured.
Deformation measurements on Taal Volcano Island have found no inflation or swelling of the volcanic edifice.
Volcano Island has been partly evacuated since 23 March, but a small number of residents have remained, particularly near the PHIVOLCS station at the N end of the island.
Information Contacts: R. Punongbayan, PHIVOLCS.
July 1991 (BGVN 16:07) Cite this Report
Abnormal seismicity continues
Abnormally high levels of seismicity continued as of mid-August. Up to 5 small high-frequency earthquakes were recorded daily 9-12 August. No earthquakes were felt during this time. The main crater lake temperature remained at 31°C. Close monitoring of the volcano continued.
Information Contacts: R. Punongbayan, PHIVOLCS.
January 1992 (BGVN 17:01) Cite this Report
Earthquake swarm, deformation, and new fissures document apparent intrusion; evacuations
A sudden increase in local seismicity began early 14 February, reaching a peak of 385 high-frequency earthquakes recorded between 1200 on 14 February and 0600 on 15 February. Many were felt in 6 towns near the shores of Lake Taal, which fills the 15 x 22 km caldera. The active cone forms an island near the center of Lake Taal. According to press reports, volcanologists observed that water temperature in the island's crater lake (1.0 x 1.4 km) increased by several degrees, and that a bulge and several fissures (up to 400 m long) had formed on the volcano's N flank. A Notice to Airmen was issued at 1445 on 14 February, advising all aircraft to exercise caution and avoid flying over the area. PHIVOLCS elevated the volcano's status to Alert Level 3 on 15 February and authorities began to evacuate island residents. By the following day, >2,600 of the island's 6,000 residents had reportedly been evacuated. Seismicity quickly decreased on 15 February, and only 14 earthquakes were recorded during a 13-hour period on 16 February. Geologists suggested that the activity represented a magma intrusion episode that appeared to have stopped.
A similar episode of increased seismicity occurred in March-April 1991, with as many as 64 earthquakes (25 March) recorded under the E side of the volcano (16:3). Several thousand people were evacuated from the island. Seismicity decreased in May 1991, and no more than five earthquakes were recorded daily in early August . No inflation was observed.
Information Contacts: PHIVOLCS; T. Fox, ICAO; AP; UPI; Reuters.
February 1992 (BGVN 17:02) Cite this Report
Crater lake temperature and seismicity decline
After a brief episode of increased seismicity, deformation, and increased crater lake temperatures on 14-15 February, activity returned to more normal levels. Fieldwork by Univ of Savoie personnel indicated that temperatures of the main crater lake were gradually declining, and that seismicity was near background levels. All measurable deformation seemed to have occurred on 14 February. The Alert Level 3 status, announced on 15 February, was lowered to Level 2, and then to Level 1 in early March. Most residents of Taal island have returned home.
Information Contacts: C. Newhall, USGS.
February 1994 (BGVN 19:02) Cite this Report
Rise in seismicity, deformation, and temperature
Beginning in late February 1994, Taal stratovolcano underwent increases in seismicity, deformation, temperature, and other signs of growing instability. The stratovolcano sits in the center of a 15 x 22 km caldera occupied by Taal lake. Taal stratovolcano, which is sometimes also referred to as either Volcano Island or Taal Island, has a central, 6-km-diameter crater lake termed the main crater lake (figures 5 and 6).
| Figure 5. Map showing the key geologic and geographic features near Pinatubo and Taal. |
| Figure 6. Map of Taal caldera and vicinity with land areas shaded, water areas blank (after Ruelo, 1983). |
Starting on 21 February seismic activity increased from the previous background level of 0-2 events/week to an average of 2-3 events/day. After 22 February, the seismic station located on the N shore of the main crater lake (station MRCZ) detected swarms of small high-frequency events, swarms that went undetected elsewhere, presumably because they had shallow epicenters located close to the station. Seismicity continued to grow; during the 24-hour intervals beginning at 0600 on 13 and 14 March there were 396 and 406 events, respectively. Many events took place at shallow depths (typically shallower than 3 km), beneath the central-to-SW portion of the caldera. Harmonic tremor was also reported, interpreted as due to magma intruding below the stratovolcano's central crater.
Deformation and precise leveling surveys conducted 10-22 February indicated slight inflation of the SW portion of Volcano Island. In mid-March an uplift of 14 cm was measured on the E side of the island; on 13 March both the N and SE sides inflated on the order of 10-20 cm. Around the same time researchers found two newly formed open cracks or fissures. They were approximately 70 m apart on the SE corner of Volcano Island, trending N55°W and N88°W, and were traced as discontinuous segments approaching the basal slopes of the main crater. The fissures had opened 8-10 mm, consistent with inflation of the edifice. Newhall and Dzurisin (1988) referred to extensive NE-trending ground cracks outside the caldera associated with the 1911 eruption.
Temperature measured near the bottom of the main crater lake rose abruptly on 13 February, from 30°C to 50°C, and remained high for about 12 hours before dropping back to 30°C. Eight days later a smaller 4°C rise in bottom-water temperature took place. Sometime during this interval the temperature of surface waters of the main crater lake also rose by 3°C. Temperature increases of 1-3°C began on 14 February at most of the ground probe holes in the Mount Tabaro area, on the SW side of Volcano Island (Ruelo, 1983).
On 12 March, data from acoustic sensors located about 25 m above the bottom of the main crater lake showed a significant increase in bubbling activity, which declined slightly the next day. The increased bubbling suggests significantly higher pressure beneath the stratovolcano, consistent with the postulated shallow magma chamber.
In response to growing instability PHIVOLCS elevated their alert status to Alert Level 3 on 11 March, suggesting that eruptive activity could occur within a period of weeks. In concert with the newly elevated alert level, the Manila Flight Information office issued a volcanic ash advisory in a NOTAM (Notice To Airmen, a notice to the aviation and meteorological communities) to avoid flying over the volcano. PHIVOLCS maintained Alert Level 3 as of the last available report on 15 March. They also mentioned "...partial evacuation of Volcano Island as per the recommendation of the Batangas Provincial Disaster Coordinating Council." The evacuations were a common theme in a series of reports by Reuters News Service on the situation at Taal. The reports were unclear, however, on both the number of people evacuated from Volcano Island, and the circumstances of their departure; one report told of hundreds who fled, the other told of thousands who were ordered to flee.
Several of these news reports also stated that some villagers from the island were unwilling to leave their homes. One report said "Farmers staying on the island have rented out horses to tourists from Manila so they can ride to the crater lake to photograph steam rising from rocks around the rim." The same report also said "Many sightseers have flocked to Tagaytay [on the N topographic Margin of the caldera, ~9 km N of Volcano Island], which offers a dramatic view overlooking the volcano." The Philippine president, Fidel Ramos, reportedly visited the volcano and said villagers who had refused to leave their homes would have time to flee if it erupted. These reports highlight the difficulty of establishing firm estimates on both the movement and behavior of people in a volcanic crisis.
Taal's most recent unrest took place in 1991-92 and involved elevated seismicity, deformation, and crater lake temperatures that lasted from several days to months. These conditions did not lead to eruptions. In many other cases, 34 since 1572, Taal did discharge, and in six cases these eruptions led to fatalities. In 1965 Taal ejected an estimated 9 x 107 m3 of material. The eruption had a Volcanic Explosivity Index (VEI) of 4 and produced a base surge that sandblasted objects up to 8 km away. The volcano monitoring system at Taal has been improved since the 1992 crisis. Improvements include telemetry-linked sensors for seismic, temperature, radon gas, and lake geochemistry. A Japanese refraction seismic experiment recently attempted to delineate a shallow (1-2 km deep) magma chamber beneath Volcano Island that was detected in a similar experiment in 1993.
References. Newhall, C.G., and Dzurisin, D., 1988, Historical unrest at large calderas of the world: U.S. Geological Survey Bulletin 1855, v. 1, 598 p.
Ruelo, Hernulfo B., 1983, Morphological and crater development of Mt. Tabaro eruption site, Taal volcano: Philippines, Philippine Journal of Volcanology, v. 1, no. 2, p. 19-68.
Information Contacts: PHIVOLCS; Bureau of Meteorology, Australia; Chris Newhall, Univ. of Washington.
December 2004 (BGVN 29:12) Cite this Report
New episode of seismic unrest began in September 2004
The Taal seismic monitoring network began to record significant volcanic earthquakes on 23 September 2004. In general, the numbers of these events occurring through 29 October increased, with a maximum 13 earthquakes on 15 October. Some of these earthquakes were instrumentally recorded with relatively large amplitudes although none were felt by residents on Volcano Island. Initial earthquake locations showed epicenters dispersed in the vicinity of Main Crater, to the NNW near Binintiang Malaki, and to the SSE near Calauit. Surface observations, however, did not indicate any significant change in the thermal and steam emission characteristics of the Main Crater lake area. The increased seismicity is an indication of a low-level episode of unrest, although at this time there is no clear indication of an impending eruption. A series of volcanic earthquakes was recorded on 9 January 2005. Two of these earthquakes, only one minute apart, were felt in Pira-piraso.
PHIVOLCS raised the hazard status on 29 October from Alert Level 0 to Alert Level 1, meaning that there was a slight increase in seismic activity but no eruption is imminent. PHIVOLCS recommend as off-limits the Main Crater area because sudden steam explosions may occur or high concentrations of noxious gases may accumulate. Several fissures traversing the Daang Kastila Trail are also potentially hazardous as possible sites of future steam emission. PHIVOLCS is conducting several enhancements of the monitoring system at Taal with deployment of more seismometers and ground-deformation surveillance equipment. The entire Volcano Island is a Permanent Danger Zone and permanent settlement is strictly prohibited.
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P. Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/).
August 2006 (BGVN 31:08) Cite this Report
Ongoing seismic unrest
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) notified the public on 26 September 2006 of ongoing seismic unrest at Taal. The Main Crater Seismic Station recorded 29 volcanic earthquakes during the 24-hour period from 0600 hours on 25 September. Five of these earthquakes, at 0233, 0234, 0242, 0247, and 0249 hours on 26 September, were felt at Modified Mercalli Intensities II to III by residents on Volcano Island. The earthquakes were accompanied by rumbling sounds. Initial locations showed epicenters generally dispersed in the vicinity of Daang Kastila (NE), Tibag (N), Tablas (NE), Mataas na Gulod (NE), and Panikihan (NW). This seismic activity was notably higher than the usual levels, generally only five or less events detected in 24 hours.
Surface thermal observations, however, did not indicate significant change in the thermal and steam emission manifestations of the Main Crater lake area. The increase in seismicity at Taal reflects a low-level episode of unrest. However, there is still no indication of an impending eruption. Possible precursors, such as increased steam emission, increased temperatures of steam vents at the Main Crater lake waters and adjacent areas are being monitored continuously. The ongoing seismic unrest could intensify in the coming days or weeks so that PHIVOLCS recommends appropriate vigilance by the public when visiting the island.
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/).
January 2007 (BGVN 32:01) Cite this Report
Elevated seismicity, deformation, and hydrothermal activity during 2006
On 26 September 2006, the Philippine Institute of Volcanology and Seismology (PHILVOLCS) announced ongoing seismic unrest at Taal (a low lying caldera ~ 45 km S of Manila). The Main Crater Seismic Station recorded 29 volcanic earthquakes during the 24 hours after 0600 on 25 September 2006. Five (5) of these occurred at 0233, 0234, 0242, 0247, and 0249 and were felt at Intensities II to III by residents on Volcano Island (figure 7 and 8). These earthquakes were accompanied by rumbling sounds. Initial computations showed epicenters generally dispersed toward northerly locations in the vicinity of Daang Kastila (NE), Tibag (N), Tablas (NE), Mataas na Gulod (NE), and Panikihan (NW).
| Figure 7. A map of Taal volcano indicating the location of components of the monitoring network (seismic stations, telemetry repeater stations, reflector, and various kinds of survey and measuring points). Volcano island (the large island in the N-central part of the caldera lake) is the site of all historical eruptions. Contour interval is 100 m. Courtesy of PHIVOLCS. |
| Figure 8. Photograph taken from the top of the N topographic margin of Taal, looking S across Lake Taal and Volcano Island, 28 May 2001. The topographic high on the far side of the lake is Mt. Macolod. Copyrighted photograph by Franck Landais (provided by Panoramio.com). |
This seismic activity was notably higher than usual, which during quiet periods is generally only five or less events detected in 24 hours. Surface thermal observations, however, did not indicate significant change in the thermal and steam emission manifestations in the Main Crater Lake area. The increase in seismicity reflected a low-level episode of unrest. However, there is still no indication of an impending eruption.
Taal manifested a sustained moderate level of seismic activity since 18 November 2006, characterized by occasional large amplitude volcanic earthquakes. During one 24-hour period, 10 volcanic earthquakes were detected. Ground deformation surveys conducted during 28 November-6 December 2006 revealed the edifice inflated 14.0 mm, suggesting possible magma intrusion. The Main Crater lake water became more acidic since 12 September 2006, and the newly formed mud geyser, which is now merged with the Crater Lake due to increase in water level, continues to be very active. The increasing acidity and hydrothermal activity are probably caused by the injection of hot gases and fluids coming from below the crater floor.
According to PHIVOLCS in its Taal Volcano Advisory of 14 December 2006, the above observations indicated a significant increase in activity although no eruption is imminent. Alert Level 1 continued, making the Main Crater off-limits to the public because of the chance of sudden steam explosions and high toxic gas concentrations.
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph); Panoramio.com, Calle Rosa Zaragoza 8, 03360 Callosa de Segura (Alicante), Spain (URL: http://www.panoramio.com/photo/40914).
February 2011 (BGVN 36:01) Cite this Report
Intermittent non-eruptive unrest during 2008-2010
As previously reported (BGVN 32:01), during the last four months of 2006 Taal displayed restlessness. This report discusses Taal seismicity, deformation, and hydrothermal behavior (steaming, and temperature changes in lake water at Main Crater) that occurred intermittently during 2008, 2010, and 2011.
Taal (also known as Talisay) is a lake-filled, 15 x 20 km caldera located on SW Luzon Island 65 km S of Manila (figure 9). The lake engulfs a large island with several thousand residents, Volcano Island, the place where all historical eruptions have vented (figures 10 and 11). Restlessness described herein was not confined to the area beneath the island.
| Figure 9. Index map of the Philippines showing Manila (the Capital) and several major volcanoes including Taal. Courtesy of Lyn Topinka (US Geological Survey). |
| Figure 10. A map showing Taal caldera and surroundings. Notice that the caldera lies at the intersection of major faults and the topographic margin extends well beyond the caldera lake's margin. Courtesy of NASA Earth Observing System (EOS) Volcanology and their slide set compiled by Peter Mouginis-Mark (University of Hawaii). |
| Figure 11. Photo of the Taal caldera lake and Volcano Island taken from the N in November 1999. Courtesy of NASA Earth Observing System (EOS) Volcanology and their slide set compiled by Peter Mouginis-Mark (University of Hawaii). |
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) announced in August 2008 that seismic unrest continued. On 28 August 2008, ten volcanic earthquakes occurred, two of which were felt and heard as rumbling sounds by residents in the Pira-Piraso village on Volcano Island. The earthquakes were located NE of the island near the Daang Kastila area (below Taal caldera's N rim) at estimated depths of 0.6-0.8 km. Surface observations indicated no change in the main crater lake area. The Alert Level remained at 1 (scale is 0-5, with 0 referring to No Alert).
On 8 June 2010, PHIVOLCS raised the Alert Level for Taal to 2 because of changes in several monitored parameters that began in late April. Since 26 April, the number and magnitude of volcanic earthquakes had increased. Most signals were high-frequency earthquakes, but at least one, on 2 June, was low-frequency. Steam emissions from the N and NE sides of Main Crater occasionally intensified. Deformation data showed slight inflation since 2004; measurements taken at the SE side of Taal on 7 June showed further inflation by 3 mm.
In addition to increased seismicity, the temperature of the Main Crater Lake increased from 32°C on 11 May to 34°C on 24 May. According to PHIVOLCS, the ratios of Mg:Cl and SO4:Cl, as well as total dissolved solids in the lake, all increased. Temperature measurements of the main crater lake did not increase further, remaining between 33-34°C.
PHIVOLCS proposed that the high frequency earthquakes could be the result of active rock fracturing associated with magma intrusion beneath the volcano, and that the fractures could serve as passageways through which hot gases from the intruding magma could escape into the lake.
According to news reports (Xinhua, Philippine Daily Inquirer), the more than 5,000 residents living near Taal were advised to evacuate their homes voluntarily. On 10 June, the Philippine Coast Guard sent five teams of divers and rescue swimmers with rubber boats and medical teams to its forward command post to help evacuate, if necessary, these residents. A news report (Philippine Daily Inquirer), however, indicated that most residents refused to leave without an official order.
The number of earthquakes recorded daily gradually declined to background levels beginning the second week of July 2010. Hydrothermal activity in the N and NE sides of the main crater and Daang Kastila also decreased. Precise leveling measurements conducted during 13-21 July along the NE, SE, and SW flanks detected minimal inflation. On 2 August, PHIVOLCS lowered the Alert Level to 1.
According to PHIVOLCS, seismic activity increased during the first week of September 2010. From 1-27 September 2010, a total of 274 volcanic earthquakes, or an average of 10 events/day, was recorded. However, given that field surveys conducted at the Main Crater and at the 1965-1977 "New Eruption" site (SW edge of Main Crater) indicated no anomalous thermal or surface activity.
PHIVOLCS reported that a December 2010 deformation survey showed slight inflation compared to a September 2010 survey. Field observations on 10 and 18 January revealed no significant changes. Weak steaming from a thermal area inside the main crater was noted and the lake temperature, acidity, and color were normal. During 15-16 January 2011, ten volcanic earthquakes were detected, two of which were felt by residents of Pira-Piraso, on the N side of the island. On 17 January three volcanic earthquakes were detected and on 18 January only one was reported. Between 18-30 January, up to seven daily volcanic earthquakes were detected by the seismic network.
Field observations during 23-25 January 2011 revealed an increase in the number of steaming vents inside the main crater and a drop in the lake level there. The lake water temperature and pH values remained normal. Visual observations on 27 January showed weak steaming at a thermal area in the crater.
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph).Pete Mouginis-Mark, Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://eos.higp.hawaii.edu/ppages/pinatubo/8.taal/?); Xinhua (URL: http://www.xinhuanet.com/english2010); Philippine Daily Inquirer (URL: http://www.inquirer.net/).
June 2020 (BGVN 45:06) Cite this Report
Eruption on 12 January with explosions through 22 January; steam plumes continuing into March
Taal volcano is in a caldera system located in southern Luzon island and is one of the most active volcanoes in the Philippines. It has produced around 35 recorded eruptions since 3,580 BCE, ranging from VEI 1 to 6, with the majority of eruptions being a VEI 2. The caldera contains a lake with an island that also contains a lake within the Main Crater (figure 12). Prior to 2020 the most recent eruption was in 1977, on the south flank near Mt. Tambaro. The United Nations Office for the Coordination of Humanitarian Affairs in the Philippines reports that over 450,000 people live within 40 km of the caldera (figure 13). This report covers activity during January through February 2020 including the 12 to 22 January eruption, and is based on reports by Philippine Institute of Volcanology and Seismology (PHIVOLCS), satellite data, geophysical data, and media reports.
| Figure 12. Annotated satellite images showing the Taal caldera, Volcano Island in the caldera lake, and features on the island including Main Crater. Imagery courtesy of Planet Inc. |
| Figure 13. Map showing population totals within 14 and 17 km of Volcano Island at Taal. Courtesy of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA). |
The hazard status at Taal was raised to Alert Level 1 (abnormal, on a scale of 0-5) on 28 March 2019. From that date through to 1 December there were 4,857 earthquakes registered, with some felt nearby. Inflation was detected during 21-29 November and an increase in CO2 emission within the Main Crater was observed. Seismicity increased beginning at 1100 on 12 January. At 1300 there were phreatic (steam) explosions from several points inside Main Crater and the Alert Level was raised to 2 (increasing unrest). Booming sounds were heard in Talisay, Batangas, at 1400; by 1402 the plume had reached 1 km above the crater, after which the Alert Level was raised to 3 (magmatic unrest).
Phreatic eruption on 12 January 2020. A seismic swarm began at 1100 on 12 January 2020 followed by a phreatic eruption at 1300. The initial activity consisted of steaming from at least five vents in Main Crater and phreatic explosions that generated 100-m-high plumes. PHIVOLCS raised the Alert Level to 2. The Earth Observatory of Singapore reported that the International Data Center (IDC) for the Comprehensive test Ban Treaty (CTBT) in Vienna noted initial infrasound detections at 1450 that day.
Booming sounds were heard at 1400 in Talisay, Batangas (4 km NNE from the Main Crater), and at 1404 volcanic tremor and earthquakes felt locally were accompanied by an eruption plume that rose 1 km; ash fell to the SSW. The Alert Level was raised to 3 and the evacuation of high-risk barangays was recommended. Activity again intensified around 1730, prompting PHIVOLCS to raise the Alert Level to 4 and recommend a total evacuation of the island and high-risk areas within a 14-km radius. The eruption plume of steam, gas, and tephra significantly intensified, rising to 10-15 km altitude and producing frequent lightning (figures 14 and 15). Wet ash fell as far away as Quezon City (75 km N). According to news articles schools and government offices were ordered to close and the Ninoy Aquino International Airport (56 km N) in Manila suspended flights. About 6,000 people had been evacuated. Residents described heavy ashfall, low visibility, and fallen trees.
| Figure 14. Lightning produced during the eruption of Taal during 1500 on 12 January to 0500 on 13 January 2020 local time (0700-2100 UTC on 12 January). Courtesy of Chris Vagasky, Vaisala. |
| Figure 15. Lightning strokes produced during the first days of the Taal January 2020 eruption. Courtesy of Domcar C Lagto/SIPA/REX/Shutterstock via The Guardian. |
In a statement issued at 0320 on 13 January, PHIVOLCS noted that ashfall had been reported across a broad area to the north in Tanauan (18 km NE), Batangas; Escala (11 km NW), Tagaytay; Sta. Rosa (32 km NNW), Laguna; Dasmariñas (32 km N), Bacoor (44 km N), and Silang (22 km N), Cavite; Malolos (93 km N), San Jose Del Monte (87 km N), and Meycauayan (80 km N), Bulacan; Antipolo (68 km NNE), Rizal; Muntinlupa (43 km N), Las Piñas (47 km N), Marikina (70 km NNE), Parañaque (51 km N), Pasig (62 km NNE), Quezon City, Mandaluyong (62 km N), San Juan (64 km N), Manila; Makati City (59 km N) and Taguig City (55 km N). Lapilli (2-64 mm in diameter) fell in Tanauan and Talisay; Tagaytay City (12 km N); Nuvali (25 km NNE) and Sta (figure 16). Rosa, Laguna. Felt earthquakes (Intensities II-V) continued to be recorded in local areas.
| Figure 16. Ashfall from the Taal January 2020 eruption in Lemery (top) and in the Batangas province (bottom). Photos posted on 13 January, courtesy of Ezra Acayan/Getty Images, Aaron Favila/AP, and Ted Aljibe/AFP via Getty Images via The Guardian. |
Magmatic eruption on 13 January 2020. A magmatic eruption began during 0249-0428 on 13 January, characterized by weak lava fountaining accompanied by thunder and flashes of lightning. Activity briefly waned then resumed with sporadic weak fountaining and explosions that generated 2-km-high, dark gray, steam-laden ash plumes (figure 17). New lateral vents opened on the N flank, producing 500-m-tall lava fountains. Heavy ashfall impacted areas to the SW, including in Cuenca (15 km SSW), Lemery (16 km SW), Talisay, and Taal (15 km SSW), Batangas (figure 18).
| Figure 17. Ash plumes seen from various points around Taal in the initial days of the January 2020 eruption, posted on 13 January. Courtesy of Eloisa Lopez/Reuters, Kester Ragaza/Pacific Press/Shutterstock, Ted Aljibe/AFP via Getty Images, via The Guardian. |
| Figure 18. Map indicating areas impacted by ashfall from the 12 January eruption through to 0800 on the 13th. Small yellow circles (to the N) are ashfall report locations; blue circles (at the island and to the S) are heavy ashfall; large green circles are lapilli (particles measuring 2-64 mm in diameter). Modified from a map courtesy of Lauriane Chardot, Earth Observatory of Singapore; data taken from PHIVOLCS. |
News articles noted that more than 300 domestic and 230 international flights were cancelled as the Manila Ninoy Aquino International Airport was closed during 12-13 January. Some roads from Talisay to Lemery and Agoncillo were impassible and electricity and water services were intermittent. Ashfall in several provinces caused power outages. Authorities continued to evacuate high-risk areas, and by 13 January more than 24,500 people had moved to 75 shelters out of a total number of 460,000 people within 14 km.
A PHIVOLCS report for 0800 on the 13th through 0800 on 14 January noted that lava fountaining had continued, with steam-rich ash plumes reaching around 2 km above the volcano and dispersing ash SE and W of Main Crater. Volcanic lighting continued at the base of the plumes. Fissures on the N flank produced 500-m-tall lava fountains. Heavy ashfall continued in the Lemery, Talisay, Taal, and Cuenca, Batangas Municipalities. By 1300 on the 13th lava fountaining generated 800-m-tall, dark gray, steam-laden ash plumes that drifted SW. Sulfur dioxide emissions averaged 5,299 metric tons/day (t/d) on 13 January and dispersed NNE (figure 19).
| Figure 19. Compilation of sulfur dioxide plumes from TROPOMI overlaid in Google Earth for 13 January from 0313-1641 UT. Courtesy of NASA Global Sulfur Dioxide Monitoring Page and Google Earth. |
Explosions and ash emission through 22 January 2020. At 0800 on 15 January PHIVOLCS stated that activity was generally weaker; dark gray, steam-laden ash plumes rose about 1 km and drifted SW. Satellite images showed that the Main Crater lake was gone and new craters had formed inside Main Crater and on the N side of Volcano Island.
PHIVOLCS reported that activity during 15-16 January was characterized by dark gray, steam-laden plumes that rose as high as 1 km above the vents in Main Crater and drifted S and SW. Sulfur dioxide emissions were 4,186 t/d on 15 January. Eruptive events at 0617 and 0621 on 16 January generated short-lived, dark gray ash plumes that rose 500 and 800 m, respectively, and drifted SW. Weak steam plumes rose 800 m and drifted SW during 1100-1700, and nine weak explosions were recorded by the seismic network.
Steady steam emissions were visible during 17-21 January. Infrequent weak explosions generated ash plumes that rose as high as 1 km and drifted SW. Sulfur dioxide emissions fluctuated and were as high as 4,353 t/d on 20 January and as low as 344 t/d on 21 January. PHIVOLCS reported that white steam-laden plumes rose as high as 800 m above main vent during 22-28 January and drifted SW and NE; ash emissions ceased around 0500 on 22 January. Remobilized ash drifted SW on 22 January due to strong low winds, affecting the towns of Lemery (16 km SW) and Agoncillo, and rose as high as 5.8 km altitude as reported by pilots. Sulfur dioxide emissions were low at 140 t/d.
Steam plumes through mid-April 2020. The Alert Level was lowered to 3 on 26 January and PHIVOLCS recommended no entry onto Volcano Island and Taal Lake, nor into towns on the western side of the island within a 7-km radius. PHIVOLCS reported that whitish steam plumes rose as high as 800 m during 29 January-4 February and drifted SW (figure 20). The observed steam plumes rose as high as 300 m during 5-11 February and drifted SW.
Sulfur dioxide emissions averaged around 250 t/d during 22-26 January; emissions were 87 t/d on 27 January and below detectable limits the next day. During 29 January-4 February sulfur dioxide emissions ranged to a high of 231 t/d (on 3 February). The following week sulfur dioxide emissions ranged from values below detectable limits to a high of 116 t/d (on 8 February).
| Figure 20. Taal Volcano Island producing gas-and-steam plumes on 15-16 January 2020. Courtesy of James Reynolds, Earth Uncut. |
On 14 February PHIVOLCS lowered the Alert Level to 2, noting a decline in the number of volcanic earthquakes, stabilizing ground deformation of the caldera and Volcano Island, and diffuse steam-and-gas emission that continued to rise no higher than 300 m above the main vent during the past three weeks. During 14-18 February sulfur dioxide emissions ranged from values below detectable limits to a high of 58 tonnes per day (on 16 February). Sulfur dioxide emissions were below detectable limits during 19-20 February. During 26 February-2 March steam plumes rose 50-300 m above the vent and drifted SW and NE. PHIVOLCS reported that during 4-10 March weak steam plumes rose 50-100 m and drifted SW and NE; moderate steam plumes rose 300-500 m and drifted SW during 8-9 March. During 11-17 March weak steam plumes again rose only 50-100 m and drifted SW and NE.
PHIVOLCS lowered the Alert Level to 1 on 19 March and recommended no entry onto Volcano Island, the area defined as the Permanent Danger Zone. During 8-9 April steam plumes rose 100-300 m and drifted SW. As of 1-2 May 2020 only weak steaming and fumarolic activity from fissure vents along the Daang Kastila trail was observed.
Evacuations. According to the Disaster Response Operations Monitoring and Information Center (DROMIC) there were a total of 53,832 people dispersed to 244 evacuation centers by 1800 on 15 January. By 21 January there were 148,987 people in 493 evacuation. The number of residents in evacuation centers dropped over the next week to 125,178 people in 497 locations on 28 January. However, many residents remained displaced as of 3 February, with DROMIC reporting 23,915 people in 152 evacuation centers, but an additional 224,188 people staying at other locations.
By 10 February there were 17,088 people in 110 evacuation centers, and an additional 211,729 staying at other locations. According to the DROMIC there were a total of 5,321 people in 21 evacuation centers, and an additional 195,987 people were staying at other locations as of 19 February.
The number of displaced residents continued to drop, and by 3 March there were 4,314 people in 12 evacuation centers, and an additional 132,931 people at other locations. As of 11 March there were still 4,131 people in 11 evacuation centers, but only 17,563 staying at other locations.
Deformation and ground cracks. New ground cracks were observed on 13 January in Sinisian (18 km SW), Mahabang Dahilig (14 km SW), Dayapan (15 km SW), Palanas (17 km SW), Sangalang (17 km SW), and Poblacion (19 km SW) Lemery; Pansipit (11 km SW), Agoncillo; Poblacion 1, Poblacion 2, Poblacion 3, Poblacion 5 (all around 17 km SW), Talisay, and Poblacion (11 km SW), San Nicolas (figure 21). A fissure opened across the road connecting Agoncillo to Laurel, Batangas. New ground cracking was reported the next day in Sambal Ibaba (17 km SW), and portions of the Pansipit River (SW) had dried up.
| Figure 21. Video screenshots showing ground cracks that formed during the Taal unrest and captured on 15 and 16 January 2020. Courtesy of James Reynolds, Earth Uncut. |
Dropping water levels of Taal Lake were first observed in some areas on 16 January but reported to be lake-wide the next day. The known ground cracks in the barangays of Lemery, Agoncillo, Talisay, and San Nicolas in Batangas Province widened a few centimeters by 17 January, and a new steaming fissure was identified on the N flank of the island.
GPS data had recorded a sudden widening of the caldera by ~1 m, uplift of the NW sector by ~20 cm, and subsidence of the SW part of Volcano Island by ~1 m just after the main eruption phase. The rate of deformation was smaller during 15-22 January, and generally corroborated by field observations; Taal Lake had receded about 30 cm by 25 January but about 2.5 m of the change (due to uplift) was observed around the SW portion of the lake, near the Pansipit River Valley where ground cracking had been reported.
Weak steaming (plumes 10-20 m high) from ground cracks was visible during 5-11 February along the Daang Kastila trail which connects the N part of Volcano Island to the N part of the main crater. PHIVOLCS reported that during 19-24 February steam plumes rose 50-100 m above the vent and drifted SW. Weak steaming (plumes up to 20 m high) from ground cracks was visible during 8-14 April along the Daang Kastila trail which connects the N part of Volcano Island to the N part of the main crater.
Seismicity. Between 1300 on 12 January and 0800 on 21 January the Philippine Seismic Network (PSN) had recorded a total of 718 volcanic earthquakes; 176 of those had magnitudes ranging from 1.2-4.1 and were felt with Intensities of I-V. During 20-21 January there were five volcanic earthquakes with magnitudes of 1.6-2.5; the Taal Volcano network (which can detect smaller events not detectable by the PSN) recorded 448 volcanic earthquakes, including 17 low-frequency events. PHIVOLCS stated that by 21 January hybrid earthquakes had ceased and both the number and magnitude of low-frequency events had diminished.
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Disaster Response Operations Monitoring and Information Center (DROMIC) (URL: https://dromic.dswd.gov.ph/); United Nations Office for the Coordination of Humanitarian Affairs, Philippines (URL: https://www.unocha.org/philippines); James Reynolds, Earth Uncut TV (Twitter: @EarthUncutTV, URL: https://www.earthuncut.tv/, YouTube: https://www.youtube.com/user/TyphoonHunter); Chris Vagasky, Vaisala Inc., Louisville, Colorado, USA (URL: https://www.vaisala.com/en?type=1, Twitter: @COweatherman, URL: https://twitter.com/COweatherman); Earth Observatory of Singapore, Nanyang Technological University, 50 Nanyang Avenue, Singapore (URL: https://www.earthobservatory.sg/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Relief Web, Flash Update No. 1 - Philippines: Taal Volcano eruption (As of 13 January 2020, 2 p.m. local time) (URL: https://reliefweb.int/report/philippines/flash-update-no-1-philippines-taal-volcano-eruption-13-january-2020-2-pm-local); Bloomberg, Philippines Braces for Hazardous Volcano Eruption (URL: https://www.bloomberg.com/news/articles/2020-01-12/philippines-raises-alert-level-in-taal-as-volcano-spews-ash); National Public Radio (NPR), Volcanic Eruption In Philippines Causes Thousands To Flee (URL: npr.org/2020/01/13/795815351/volcanic-eruption-in-philippines-causes-thousands-to-flee); Reuters (http://www.reuters.com/); Agence France-Presse (URL: http://www.afp.com/); Pacific Press (URL: http://www.pacificpress.com/); Shutterstock (URL: https://www.shutterstock.com/); Getty Images (URL: http://www.gettyimages.com/); Google Earth (URL: https://www.google.com/earth/).
October 2021 (BGVN 46:10) Cite this Report
Phreatomagmatic eruptions during early July 2021
Taal is part of a caldera system located in southern Luzon Island and has had historical eruptions dating back to 3,580 BCE. The caldera is 15 x 20 km contains Lake Taal, with a depth of 160 m, and an island that also contains a lake within the Main Crater. The previous eruption occurred during January 2020 and was characterized by phreatic and magmatic explosions, ash plumes and ashfall, and significant sulfur dioxide plumes (BGVN 45:06). This report covers activity consisting of gas-and-steam emissions and sulfur dioxide plumes during May 2020 through September 2021, including a new phreatomagmatic eruption during 1-9 July 2021 using reports from the Philippine Institute of Volcanology and Seismology (PHIVOLCS) and various satellite data.
Summary of activity during May 2020-May 2021. During May 2020 through June 2021, activity was relatively low and consisted of dominantly volcanic earthquakes, rock-fracturing processes, and weak gas-and-steam emissions originating from vents on the Main Crater and fissure vents along the Daang Kastila Trail. On 29 March 2020 continuous GPS monitoring detected slow inflation on the NW section of the caldera. This inflation was also recorded by electronic tiltmeters in the NW of Volcano Island during the second week of July 2020.
PHIVOLCS reported that unrest increased around 13 February 2021, with continued ground deformation and a higher number of volcanic tremor events (866 were reported during 13 February and 9 March 2021) compared to previous months. Additionally, observations made during mid-February 2021 showed an increase in the Main Crater Lake (MCL) acidity to a pH 1.59, from a pH of 2.79 in January 2020. As a result, PHIVOLCS raised the Volcano Alert Level from 1 to 2 (on a scale of 0-5) on 9 March, which suggests that probable magmatic activity may occur. On 10 March significant sulfur dioxide emissions were measured, averaging 1,327 metric tons/day (t/d). The next day, 11 March, the sulfur dioxide emissions averaged 795 t/d. On 12 March a short (2.5 minutes) burst of gas-and-steam plumes rose 400-500 m above the Main Crater at 1411, accompanied by SO2 emissions that averaged 582 t/d. Diffuse steam plumes rose 50 m above fumarolic vents on the inner N and E walls during the rest of the day. An episode of high-temperature gas upwelling to the crater lake’s surface occurred during 1830-2045 on 14 March.
Daily volcanic tremor and earthquakes continued to be reported with variable durations, accompanied by gas-and-steam emissions. Though the near daily SO2 measurements were variable, there was a notable increase in emissions beginning in early April; the highest average was 7,576 t/d on 30 May. Upwelling of hot volcanic fluids in the crater lake was accompanied by steam plumes that were 300-600 m tall on 27 April, 30 April, and 4 May. On 3 May a gas-and-steam plume rose 500 m above the Main Crater Lake. A strong gas-and-steam plume rose 2 km above the Main Crater at 2300 and drifted SW, accompanied by SO2 emissions that averages 3,051 t/d. Low-level background tremor was consistently detected beginning on 8 April and continuing through the reporting period. Electronic tilt, continuous GPS and InSAR monitoring data showed that deflation was occurring on the island during April through September 2021 while the rest of the region has been undergoing slow extension since 2020.
Activity during June-July 2021. Low-level background tremor continued with frequent volcanic earthquakes, low-frequency earthquakes, and volcanic tremor. Gas-and-steam emissions during June rose as high as 2.5 km above the Main Crater and gradually increasing SO2 emissions reached a maximum of 14,326 t/d on 28 June. Peak measurements coincided with periods of vigorous upwelling at the Main Crater Lake; the upwelling was continuous from 1800 on 9 June to 1000 on 10 June, producing gas-and-steam plumes that rose 1.5 km and drifted mainly NW. Stronger gas-and-steam plumes were also reported, beginning on 28 June, rising as high as 3 km and drifting SW, SE, and NNW. Voggy conditions were also reported impacting the NE and E lakeshore communities; some of the residents reported adverse effects as a result.
On 1 July at 1516 a dark gray phreatomagmatic plume rose 1 km above the lake, continuing for about 5 minutes, prompting PHIVOLCS to raise the Volcano Alert Level from 2 to 3 at 1537 (figure 22). The explosion followed strong SO2 emissions on 28 June and 1 July (14,241 and 13,287 t/d, respectively). According to the Philippine Coast Guard, authorities evacuated residents in Banyaga, Bilibinwang, Gulod, Boso-boso, and Lakeshore Bugaan East due to the rise in the VAL. Successive phreatomagmatic events lasting no longer than two minutes each were detected at 1826, 1921, 1941, and 2020, producing jetted plumes 200 m above the Main Crater Lake. During 1-2 July the seismic network detected twenty-nine volcanic earthquakes, which included one explosion, twenty-two low-frequency earthquakes, and two volcanic tremors. Vog was also observed over the volcano and in the surrounding area. On 2 July a series of three short phreatomagmatic bursts occurred at 1025, 1047, and 1101, producing jetted plumes that rose 100 m above the Main Crater Lake. SO2 emissions remained high on 3 July with an average of 14,699 t/d. A PHIVOLCS volcano advisory issued on 4 July at 1615 reported markedly high sulfur dioxide emissions with an average of 22,628 t/d, following 26 strong and very shallow low-frequency volcanic earthquakes below the E part of the island. Lake upwelling persisted during 5-6 July with steam-and-gas plumes rising 2.5-3 km. Sulfur dioxide emissions averaged 5,299 t/d on 5 July. A DROMIC (Disaster Response Operations Monitoring and Information Center) report stated that 3,027 people were in 20 evacuation centers, and 2,759 people were in private residences by 6 July.
| Figure 22. Webcam image of the phreatomagmatic plume rising above Taal on 1 July at 1516. Courtesy of PHIVOLCS. |
A series of five phreatomagmatic bursts were detected at 0847, 0915, 0926, 1156, and 2141 on 7 July, producing jetted plumes that rose 700 m above the Main Crater Lake; in addition, a brief event at 1718 on the same day produced a gray plume that rose 300 m high and drifted SE. On 8 July another series of five short phreatomagmatic bursts were detected at 0647, 0606, 0921, 0950, and 0259 on 9 July that produced jetted plumes that rose 200 m above the Main Crater Lake. High levels of SO2 emissions continued to be recorded, rising 1.2 km above the Main Crater and drifting NW, and averaging 6,095 t/d on 8 July. According to a DROMIC report, 10,408 people were in evacuation centers or private residences by 12 July. On 14 July an SO2 plume rose 1.8 km above the crater and drifted SW.
Daily gas-and-steam plumes and frequent sulfur dioxide emissions continued; tremor events at 1018 and 1038 on 20 July were felt by residents of Pira-piraso in the NE sector of Volcano Island. The DROMIC report stated that 3,839 people were in evacuation centers or private residences on 20 July. On 23 July at 1930 PHIVOLCS lowered the Volcano Alert Level from 3 (Magmatic Unrest) to 2 (Decreased Unrest). The activity during 1-9 July was accompanied by a total of 1,201 tremor events that ranged from an M 1.8 to an M 4.6; of these, 789 were volcanic tremor, 365 were low-frequency, 27 were hybrid, and 8 were volcano-tectonic earthquakes. Campaign Flyspec data showed that sulfur dioxide emissions averaged 12,161 t/d during the first week of July, which then decreased to 4,763 t/d during 8-22 July. Unrest has been characterized by seismicity, generally declining volcanic gas emissions, and slight ground deformation after 9 July.
During August and September, activity remained low and included volcanic tremor and weak gas-and-steam emissions that rose 5-3,000 m above the crater. Electronic tiltmeters, GPS, and InSAR data continued to show deflation in the region. Sulfur dioxide emissions was a maximum value of 15,508 t/d on 14 September. Vog was also reported over the area during 12-25 August and 29-30 September. During 17-18 August residents reported smelling sulfuric odor in Barangay Buso-Buso and Gulod, Laurel, Batangas and during 19-20 August some residents in Talisay and Barangay Agoncillo reported adverse effects.
Satellite data. Frequent and distinct sulfur dioxide plumes drifting various directions were observed using satellite sensors during the reporting period. Strong SO2 plumes were notable during 27-30 June 2021 leading up to the phreatomagmatic events on 1 July, based on data from the TROPOMI instrument on the Sentinel-5P satellite (figure 23). Similar strong plumes that exceeded 2 Dobson Units (DUs) continued to be visible in satellite data through September (figure 24).
| Figure 23. Consecutive distinct sulfur dioxide plumes were detected at Taal on 27 June (top left), 28 June (top right), 29 June (bottom left), and 30 June (bottom right) 2021 that drifted in different directions, using the TROPOMI instrument on the Sentinel-5P satellite. These strong SO2 plumes led to the phreatomagmatic plume that occurred on 1 July. The plumes shown here exceeded 2 Dobson Units (DUs). Courtesy of NASA Global Sulfur Dioxide Monitoring Page. |
| Figure 24. Strong sulfur dioxide plumes continued to rise from Taal on 7 June (top left), 19 August (top right), 6 September (bottom left), and 28 September (bottom right) 2021 that drifted in different directions, detected using the TROPOMI instrument on the Sentinel-5P satellite. The plumes shown here exceeded 2 Dobson Units (DUs). Courtesy of NASA Global Sulfur Dioxide Monitoring Page. |
MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data detected occasional low-power thermal anomalies during January 2020 through August 2021, though during September 2020 through July 2021 no anomalies were identified in the summit crater (figure 25).
| Figure 25. Occasional thermal anomalies (red dots) were detected at the summit of Taal during January 2020 through August 2021, as recorded by the Sentinel-2 MODIS Thermal Volcanic Activity data (bands 12, 11, 8A). During September 2020 through July 2021 no thermal anomalies were detected at the summit. Courtesy of MIROVA. |
Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Philippine Coast Guard (PCG), National Headquarters Philippine Coast Guard 139 25th Street, Port Area, Manila 108, Philippines (URL: https://coastguard.gov.ph/); Disaster Response Operations Monitoring and Information Center (DROMIC), (URL: https://dromic.dswd.gov.ph/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).
