Report on Kanlaon (Philippines) — June 1988
Scientific Event Alert Network Bulletin, vol. 13, no. 6 (June 1988)
Managing Editor: Lindsay McClelland.
Kanlaon (Philippines) Series of ash ejection
Please cite this report as:
Global Volcanism Program, 1988. Report on Kanlaon (Philippines) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 13:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198806-272020.
10.412°N, 123.132°E; summit elev. 2435 m
All times are local (unless otherwise noted)
A series of ash ejections began on 21 June. During the initial outburst from 1725 to 1740, light-grayish steam clouds rose to a maximum height of 300 m above the crater. Traces of ash were noted at the village of Mananawin on the SE slope at 980 m elevation. This event was not recorded by the flank seismic network. Previous ash ejections in April 1987 were similarly not recorded (12:4-5).
Ash ejections ocurred again the next day at 1230 and 1418 and were recorded as small-amplitude (0.5 mm) harmonic tremors with durations not exceeding 2 minutes. The maximum ash cloud height was 600 m above the crater. Sulfur stench was noted by SE flank residents. On 24 June, ash ejections occurred at 1155 and 1455, accompanied by faint rumbling sounds. Ash from the 400-m-high eruption clouds was deposited on the upper SE slopes. No eruption signal was recorded by PHIVOLCS seismic stations.
Another ash ejection occurred at 1105 on 27 June, accompanied by an explosion-type earthquake that had a maximum double amplitude of 4.0 mm and lasted for 1 minute. As observed from the Canlaon Volcano Observatory (8.7 km SE of the crater), the cloud rose 500 m above the crater and deposited ash along the SW upper slopes. Background seismicity varied from 5 to 18 events/day following the first outburst. Steam emission between ash ejections covered 20-50% of the crater's area.
Since the ash eruption of April 1987, slight inflation of the SE flank and moderate seismicity have occurred (12:4-5).
Further Reference. Sincioco, J., 1988, The 1988 Eruptive Activity of Canlaon Volcano; Phivolcs Observer, v. 4, no. 3, p. 3.
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.
Information Contacts: PHIVOLCS.