Mayon Volcano Bulletin 4 Apr 2000

Report
from Philippine Institute of Volcanology and Seismology
Published on 04 Apr 2000
0700H

The Mayon Volcano seismic network recorded twenty nine (29) low frequency and two (2) high frequency volcanic earthquakes and twelve (12) episodes of low frequency short duration tremors for the past 24 hours. Ground deformation measurement using the Electronic Distance Meter along the northwest slope of the volcano showed no significant change from its deflated state. The sulfur dioxide emission rate decreased from 7,000 tonnes/day (t/d) to yesterday's reading of 6,270 t/d. Crater glow continued to be observed in the evening.

The persistent occurrence of low and high frequency volcanic earthquakes and short duration harmonic tremors and high level of sulfur dioxide emission rate are associated with degassing magma. This degassing process is considered part of post-eruptive activity of the volcano. The presence of still-hot magma near the summit caused the crater to glow at night.

PHIVOLCS maintains Alert Level 2, which means that the probability of hazardous explosive eruption is now minimal. However, the public is reminded to strictly follow the six (6) kilometers radius Permanent Danger Zone. The seven (7) kilometers Extended Danger Zone in the southeast portion of the volcano remains in effect since the eruptive deposits in the vicinity of Bonga gully are still unstable and are expected to be eroded especially during intense and prolonged rainfall. Thus, secondary pyroclastic flows, rockfalls and ash fallout can occur any time. The areas of highest potential danger includes the lowlands fronting the Mabinit and Buyoan-Padang river channels in Legaspi City; Miisi in Daraga; Tumpa, Anoling and Quirangay channels in Camalig; Maninila channel in Guinobatan; Basud-Lidong channel in Sto. Domingo; Bulawan channel in Malilipot; San Vicente and Buang in Tabaco and upper Nasisi and upper Nabonton in Ligao.