MAYON VOLCANO BULLETIN 27 November 2014 8:00 A.M. Mayon Volcano’s current condition remains unstable due to slow but sustained ground deformation of the edifice caused by the movement of subsurface magma since the start of unrest this year. Ground deformation data based on precise leveling surveys made from November 18 - 21 showed slight inflation at the base of the edifice relative to November 9 - 13 surveys and also relative to baseline measurements beginning 2010. Electronic tilt data from the continuous network on the northwest flank similarly indicate continuing inflation of the edifice since August 2014, succeeding a previous inflation event in June to July 2014. The inflation events correspond to batches of magma (approximately 107cubic meters) that have been slowly intruded at depth but that have yet to be erupted at the crater, and therefore posing threat of eventual hazardous eruption at an unknown time in the near future. Meanwhile, Mayon’s seismic network did not detect any volcanic earthquake during the past 24 hours. This is consistent with the overall slow magma intrusion at depth that has characterized this year’s activity. Emission of white steam plumes was of moderate volume that drifted west-southwest. Crater glow was observed at Intensity I last night, while sulfur dioxide (SO2) emitted at the crater averaged 32 tonnes/day on 22 November 2014, which is below the baseline level during normal periods. The visual and gas parameters may denote either poor magma degassing or the generally low gas content of intruding subsurface magma. Seismicity, visual and gas parameters, however, may suddenly change within a few hours or days should magma breach the surface in an eventual eruption. Mayon Volcano’s alert status remains at Alert Level 3. At this present stage, potentially eruptible magma has already been intruded and continues to be intruded beneath the edifice. At any given time in the following weeks to months, this magma can eventually be erupted quietly as lava flows or explosively as vertical eruption columns and pyroclastic flows or both. It is strongly recommended that the 6-km radius Permanent Danger Zone (PDZ) around the volcano and the 7-km Extended Danger Zone (EDZ) on the southeastern flank be enforced due to the danger of rock falls, landslides and sudden explosions or dome collapse that may generate hazardous volcanic flows. PHIVOLCS maintains close monitoring of Mayon Volcano and any new development will be communicated to all concerned stakeholders.
Posted on: Thu, 27 Nov 2014 00:24:50 +0000
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