Report on Kanlaon (Philippines) — 20 December-26 December 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 December-26 December 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Kanlaon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 December-26 December 2017. 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 during 19-20 December there were 412 volcanic earthquakes detected at Kanlaon. A low-energy, explosion-type earthquake was detected at 0233 on 21 December associated with gas emissions from the summit area. Later in the day steam plumes rose 400 m and drifted NE. The number of daily volcanic earthquakes increased to 957 the next day and then decreased to less than 20 per day during 22-23 December; the daily count increased to 382 and 776 events on 24 and 25 December, respectively, and then decreased to 82 on 26 December. White plumes rose 300 m and drifted NE, NW, and SW on 21 December, and 700 m on 26 December; weather clouds prevented views on the other days. The Alert Level remained at 2 (on a scale of 0-5).
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.