PHIVOLCS reported continuing unrest at Taal during 25-31 October. Sulfur dioxide emissions averaged 544 tonnes per day on 27 October. There were 2-16 daily counts of small phreatomagmatic bursts during 25-29 October. The Tokyo VAAC noted that three ash plumes rose as high as 600 m (2,000 ft) a.s.l. and drifted NW and SW during 26-28 October based on SIGMETS (Significant Meteorological statements) issued by the Ninoy Aquino International Airport. Six volcanic earthquakes and a three-minute-long tremor signal were recorded during 25-26 October, four periods of volcanic tremor were recorded during 28-29 October, and 64 periods were recorded during 31 October-1 November. Upwelling gasses and hot fluids in the lake were visible early in the week; white steam emissions rose as high as 600 m above the lake on most of the days. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ).

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.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Tokyo Volcanic Ash Advisory Center (VAAC)