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) 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)