PHIVOLCS issued a special notice for Kanlaon at 2030 on 4 May, noting increased seismicity and ground deformation, and ongoing elevated sulfur dioxide emissions. Ground deformation data from continuous GPS and electronic tilt data indicated short-term inflation of the lower and mid-flanks of the volcano since March, though during the second week of April inflation was pronounced at the SE mid-flank. Real-time, continuous gas monitoring of thermal springs on the N flank detected sulfur dioxide for the first time beginning in April. Sulfur dioxide emissions at the summit crater averaged 632 tonnes per day on 1 May, lower than the average of 1,099 tonnes per day measured the day before, but higher than the average of 124 tonnes per day emitted since March. The seismic network detected 20 shallow volcanic earthquakes (M 1.2-2.4) beneath the summit crater between 2225 on 3 May until 1600 on 4 May. The Alert Level remained at 1 (on a scale of 0-5) and PHIVOLCS reminded the public to remain outside of the 4-km-radius Permanent Danger Zone.

Geological Summary. Kanlaon volcano (also spelled Canlaon) forms the highest point on the Philippine island of Negros. The massive andesitic stratovolcano is covered 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 active vent, Lugud crater, to the south. Eruptions recorded since 1866 have typically consisted of phreatic explosions of small-to-moderate size that produce minor local ashfall.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)