PHIVOLCS reported continuing unrest at Kanlaon during 11-17 September, characterized by increased seismicity and sulfur dioxide emissions. Sulfur dioxide emissions reached a record high on 11 September, averaging 11,556 tonnes/day (t/d), before decreasing slightly to 10,880 t/d on 12 September; emissions were not reported the rest of the week. The number of volcanic earthquakes detected by the seismic network was 337 during 10-11 September and 79 recorded during 11-12 September. The daily number fluctuated from 2 to 32 on the other days. Weather clouds obscured views of the summit during the second half of the week. The Alert Level remained at 2 (on a scale of 0-5) and PHIVOLCS reminded the public to remain outside of the 4-km-radius Permanent Danger Zone and warned pilots not to fly close to the volcano. According to a Disaster Response Operations Monitoring and Information Center (DROMIC) report there were a total of 2,298 people in evacuation centers as of 16 September.

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.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Disaster Response Operations Monitoring and Information Center (DROMIC)