Report on Taal (Philippines) — 13 April-19 April 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 April-19 April 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Taal (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 April-19 April 2011. Smithsonian Institution and US Geological Survey.
14.002°N, 120.993°E; summit elev. 311 m
All times are local (unless otherwise noted)
During 12-19 April, PHIVOLCS reported that between 6 and 21 daily volcanic earthquakes at Taal were detected by the seismic network. Some of the earthquakes were felt by nearby residents. Results of a ground deformation survey conducted around Volcano Island during 5-11 April showed that the edifice was slightly inflated compared to a survey from early February. The Alert Level remained at 2 (on a scale of 0-5). According to news articles, the number of people that had evacuated from around Taal rose to 1,375.
Geologic Background. 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.