Report on Taal (Philippines) — December 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 12 (December 1987)
Managing Editor: Lindsay McClelland.
Taal (Philippines) Seismicity abates; thermal activity normal
Please cite this report as:
Global Volcanism Program, 1987. Report on Taal (Philippines) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 12:12. Smithsonian Institution.
14.002°N, 120.993°E; summit elev. 311 m
All times are local (unless otherwise noted)
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.
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.
Information Contacts: PHIVOLCS.