PHIVOLCS reported that unrest at Taal continued during 9-15 June. Sulfur dioxide emissions reached the highest levels ever detected at the volcano, averaging 9,911 tonnes/day on 10 June. Peak measurements coincided with periods of vigorous upwelling at the Main Crater Lake; the upwelling was continuous from 1800 on 9 June to 1000 on 10 June, producing steam plumes that rose 1.5 km and drifted mainly NW. Residents of barangays Banyaga, Bilibinwang, and Subic Ilaya (Municipality of Agoncillo, Batangas Province) reported throat irritations and observed sudden drying or die off of crops, plants, and trees after a period of rain. Averages on the other days were also elevated at 1,725-5,837 tonnes/day, and steam plumes from periods of lake upwelling rose 1-1.5 km and drifted NE, NW, and SW.

Low-level background tremor that had begun at 0905 on 8 April continued. During 13-14 June the seismic network recorded 13 periods of volcanic tremor with durations from 1 to 270 minutes. During 14-15 June the network recorded 221 volcanic earthquakes, 29 low-frequency earthquakes, and 192 periods of volcanic tremor with durations from 1 to 135 minutes. PHIVOLCS noted the continuing state of elevated unrest, reminding the public that the Alert Level for Taal remained at 2 (on a scale of 0-5). PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater, Daang Kastila fissure (along the walking trail), and boating on Taal Lake was strictly prohibited.

Geological Summary. Taal is one of the most active volcanoes in the Philippines and has produced some powerful eruptions. 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, with several submerged eruptive centers. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)