The Philippine Institute of Volcanology and Seismology (Phivolcs) has raised the status of Mayon Volcano from Alert Level 0 to Alert Level 1.
Alert Level 1 means that "it is at an abnormal condition and has entered a period of unrest", PHIVOLCS posted on their bulletin dated September 8.
According to Mayon Volcano bulletin, its monitoring showed the following:
- Gas Emission: Sulfur Dioxide emission or SO2 flux from Mayon crater based on campaign and continuous gas measurements has consistently increased beyond the baseline level of 500 tonnes/day, exceeding 1,000 tonnes/day in some days, since July 2016. SO2 flux tends to increase through time as magma degasses with increasing rates as it moves up from great depths beneath the volcano.
- Ground Deformation: Continuous Global Positioning System and tilt measurements show a continuous inflationary trend since July 2016. Results of Precise leveling and electronic distance surveys on the last week of August 2016 indicate inflation of the edifice, possibly due to magma movement at depth.
- Volcanic Earthquake Activity: A total of 146 earthquakes were recorded by Mayon Volcano Observatory seismic network from August 3 to August 6, which were located on the southeast side 10 km away from the volcano. This earthquake swarm likely emanated from rock-fracturing processes that may or may not be associated with magmatic activity. However, seismicity has remained below baseline in the weeks succeeding the swarm.
- Other observations: Four of the 14 monitored water wells located on the southeastern side of Mayon are experiencing decrease in water discharge while one well has dried-up. Steaming activity from the crater has ranged from weak to moderate. No crater glow or banaag has been observed so far.
The Philippine national institution dedicated to provide information on the activities of volcanoes reminds the public "to avoid entry into the six-kilometer Permanent Danger Zone (PDZ) due to perennial hazards of rockfalls, avalanches, ash puffs and sudden stream-driven or phreatic eruption at the summit area which may occur without warning".
Any sudden phreatic eruption can be hazardous. In a Rappler article dated May 7, 2013, five mountain climbers die after a phreatic explosion.
"Phreatic eruptions are steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits (for example, tephra and pyroclastic-flow deposits)." USGS-
Video Report: Mayon, placed under alert level-1Video by PTV, the flagship government television network owned by the Philippine Government.
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