Report on Kanlaon (Philippines) — 11 March-17 March 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 11 March-17 March 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, 11 March-17 March 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 at Kanlaon indicated long-term slow inflation of the volcano since 2017, slow inflation of the lower flanks since May 2019, and notable inflation of the upper flanks beginning near the end of January 2020. The seismic network recorded a total of 80 volcanic earthquakes since 9 March; 77 of them were low-frequency events associated with magmatic fluids. The deformation and seismic data both indicated unrest; PHIVOLCS raised the Alert Level to 1 (on a scale of 0-5) on 11 March and reminded the public to remain outside of the 4-km-radius Permanent Danger Zone. During 12-17 March there were between two and eight volcanic earthquakes recorded daily.
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.