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.

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)