Report on Kanlaon (Philippines) — 2 July-8 July 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
2 July-8 July 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Kanlaon (Philippines). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 2 July-8 July 2003. Smithsonian Institution and US Geological Survey.
10.412°N, 123.132°E; summit elev. 2435 m
All times are local (unless otherwise noted)
As of 4 July, moderate steam-and-ash emissions continued at Canlaon, with ash columns reaching ~900 m above the summit. Low-frequency volcanic earthquakes and low-frequency short duration harmonic tremor were recorded. According to PHIVOLCS, based on Canlaon's historical behavior the mild phreatic activity that is occurring is probably related to hydrothermal disturbances at shallow depths. The absence of longer duration harmonic tremors suggested no active magma movement or intrusion. However, sudden ash emissions and explosions are still expected to occur anytime without warning. Canlaon remained at Alert Level 1 (on a scale of 0-5).
Geological Summary. 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.