Report on Kanlaon (Philippines) — 17 June-23 June 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 June-23 June 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Kanlaon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 17 June-23 June 2020. Smithsonian Institution and US Geological Survey.
10.412°N, 123.132°E; summit elev. 2435 m
All times are local (unless otherwise noted)
PHIVOLCS reported that ground deformation data from continuous GPS measurements at Kanlaon indicated slight deflation of the lower and middle flanks since January. Tilt data from instruments on the SE flank recorded continuing deflation on the lower flanks and inflation of the mid-flank since April 2020. White steam plumes rose 100-200 m above the summit and drifted NW and SW.
The seismic network recorded as many as 10 volcanic earthquakes per day during 17-21 June. A series of earthquakes beneath the lower W flank began at 1603 on 21 June, and by 0800 the next morning there were a total of 136 events recorded. Five of the earthquakes (recorded at 0101, 0104, 0134, 0206, and 0507 on 22 June) were M 3-4.7, and were felt at Intensities II to IV in La Carlota City and Bago City, Negros Occidental, and Canlaon City, Negros Oriental. During 22-23 June there were a total of 104 volcano-tectonic earthquakes beneath the W flank. 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.
Geologic Background. 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.