PHIVOLCS issued a special notice for Kanlaon at 0900 on 6 September, noting increased seismicity. The seismic network detected 36 volcanic earthquakes including 34 volcano-tectonic earthquakes between 0500 on 4 September and 0750 on 6 September at depths of 0-9 km beneath the NE flank. The earthquakes had local magnitudes of 0.8-3.4. Ground deformation data from continuous GPS and electronic tilt data had been recording inflation at the mid-flanks of the volcano since March. Sulfur dioxide emissions at the summit crater averaged 788 and 301 tonnes per day (t/d) on 7 and 11 September, respectively. The number of volcano-tectonic earthquakes decreased during the rest of the week; there were 23 recorded during 6-7 September and 2-9 daily earthquakes during 8-12 September. 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), 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)