Report on Taal (Philippines) — 26 January-1 February 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 January-1 February 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, 26 January-1 February 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 25-27 and 29-30 January, PHIVOLCS reported that up to six volcanic earthquakes at Taal were detected daily by the seismic network. Field observations during 23-25 January revealed an increase in the number of steaming vents inside Main Crater and a drop in the lake level. The lake water temperature and pH values were normal. Visual observations on 27 January showed that steaming at a thermal area in the crater was weak. The Alert Level remained at 1 (on a scale of 0-5).
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.