KANLAON WATCH | 1,217 quakes in 24 hours recorded on Negros volcano

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A plume of steam rises from the crater of Kanlaon Volcano as seen from Bacolod City last Sunday, December 10. (InterAksyon file)

MANILA, Philippines — Negros’ Kanlaon Volcano remained restive with 1,217 volcanic earthquakes recorded over the past 24 hours, the Philippine Institute of Volcanology and Seismology said Friday, December 15.

This was 210 quakes more than the 1,007 recorded on Thursday.

Phivolcs said a wispy emission of white steam-laden plumes was observed at Kanlaon’s crater. On December 13, it also measured a sulfur dioxide emission averaging 687 tons a day.

The U.S. Geological Survey says “scientists can learn a lot about changes to the magma system within a volcano by,” among others, “measuring changes in the emission rate of certain key gases, especially sulfur dioxide and carbon dioxide.”

“Sulfur dioxide is released from a volcano when magma is relatively near the surface,” it adds.

Another article on the USGS site notes that “correlation spectrometer measurements of sulfur dioxide emission were an important contributor to successful prediction of the June 1991 eruption of Mount Pinatubo,” when an initial measurement of 500 tons a day in mid-May that year increased tenfold late the same month.

Kanlaon has been on Alert Level 2, meaning “there is probable intrusion of magma at depth which may or may not lead to a magmatic eruption,” since November 15 after 279 deep volcanic earthquakes were recorded over a 24-hour period.

The recent activity followed a low-energy phreatic, or steam-driven, eruption last Saturday, December 9.

Phivolcs has reminded local government units to bar entry into the Permanent Danger Zone, the four-kilometer radius around Kalnalon’s crater, and pilots to avoid flying close to the volcano’s summit because of the dangers posed by sudden eruptions.