Report on Taal (Philippines) — 12 May-18 May 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
12 May-18 May 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Taal (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 May-18 May 2021. Smithsonian Institution and US Geological Survey.
14.002°N, 120.993°E; summit elev. 311 m
All times are local (unless otherwise noted)
PHIVOLCS reported that unrest at Taal continued during 11-18 May. Low-level background tremor that had begun at 0905 on 8 April continued, along with 0-201 daily low-frequency events, 2-355 daily volcanic earthquakes, and 0-249 periods of volcanic tremor with variable durations (1-35 minutes); seismicity was the lowest during 13-14 May. Most of the earthquakes were very shallow (less than 5 km deep) beneath Taal Volcano Island (TVI) and the NE part of Taal Lake. Upwelling of hot volcanic fluids in the crater lake during most days was accompanied by steam plumes that were as tall as 300 m. On other days fumarolic plumes from vents in Main Crater rose 5-40 m. Almost-daily measurements of sulfur dioxide emissions were 2,214-3,758 tonnes/day, though a peak of 5,179 tonnes/day was recorded on 12 May and comparable to a 13 January 2020 measurement taken when the volcano was erupting. Tilt data showed a minor but abrupt inflation signal on 17 May; slow and steady inflation of the Taal region was recorded by multiple instruments after the January 2020 eruption. On 18 May PHIVOLCS noted the continuing state of elevated unrest, reminding the public that the Alert Level for Taal remained at 2 (on a scale of 0-5). PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater, Daang Kastila fissure (along the walking trail), and boating on Taal Lake was strictly prohibited.
Geological Summary. Taal is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. Though not topographically prominent, its prehistorical eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions have caused many fatalities.