Report on Taal (Philippines) — 27 August-2 September 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 August-2 September 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Taal (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 August-2 September 2008. 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 ongoing seismic unrest at Taal on 28 August. Ten earthquakes occurred; two at Intensity II were felt by residents in the Pira-Piraso village and were accompanied by rumbling sounds. The earthquakes were located NE of the island near the Daang Kastila area at estimated depths of 0.6-0.8 km. Surface observations indicated no change in the main crater lake area. PHIVOLCS warned that the main crater was off-limits to the general public. The Alert Level remained at 1 (scale is 0-5, 0 referring to No Alert status).
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.