PHIVOLCS reported between 1 and 7 volcanic earthquakes at Kanlaon were recorded each day during 2-8 December, prior to the phreatic eruption on 9 December. Only three events were detected on 10 December, and then the number increased to 155 the next day. The number of daily volcanic earthquakes increased to 578 on 13 December, rising to 1,007 the next day, and peaking at 1,217 on the 15th. The earthquake count dropped to 149 on 16 December before returning to six or less through 19 December. White steam plumes rose 800 and 300 m above the crater on 13 and 14 December, respectively. White plumes were diffuse on 15 December; weather clouds prevented views of the summit area during 16-18 December. Sulfur dioxide emissions were 603-687 tons per day during 13-14 December. The Alert Level remained at 2 (on a scale of 0-5).

Geological Summary. Kanlaon volcano (also spelled Canlaon), the most active of the central Philippines, forms the highest point on the island of Negros. The massive andesitic stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller, but higher, historically active vent, Lugud crater, to the south. Historical eruptions, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)