Phreatic activity continued at Canlaon during 18-23 May, with ash-and-steam plumes rising to ~1 km above the volcano (~11,300 ft a.s.l.). This activity was not recorded in seismic data. The sulfur-dioxide flux on 22 May was at ~2,080 metric tons per day, much higher than the normal flux of 500 metric tons per day. Canlaon remained at Alert Level 1, with a 4-km Permanent Danger Zone around the summit off limits to visitors.

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)