Report on Taal (Philippines) — October 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 10 (October 1989)
Managing Editor: Lindsay McClelland.
Taal (Philippines) Increased seismicity; main crater inflation
Please cite this report as:
Global Volcanism Program, 1989. Report on Taal (Philippines) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:10. Smithsonian Institution.
14.002°N, 120.993°E; summit elev. 311 m
All times are local (unless otherwise noted)
Since July, seismicity at Taal has increased from background level to a maximum of 126 volcanic earthquakes/week, with at least three events recorded daily. Epicenters clustered around the main crater and about 2 km NE (near Pinagulbuan), migrating from 9 to 5 km depth, 18 August-2 October. Precise leveling and dry tilt surveys suggest inflation of the main crater and the 1965 eruption site, while a water tube tiltmeter has measured inflation of the main crater area since May.
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.