Phivolcs clarifies change in Sorsogon quake magnitude

The Philippine Institute of Volcanology and Seismology (Phivolcs) has clarified the revision it made on the strength of the Sorsogon earthquake on Monday night from its initial information bulletin of magnitude 6.4 to 5.4 in its second bulletin.

Paul Alanis, Phivolcs chief in Bicol, on Tuesday said the 6.4 magnitude was the first computation produced by their instruments.

He said their second bulletin on magnitude 5.4 was issued after more data were received by their monitoring system.

“We only had reports from our 30 stations when we posted the earthquake had a magnitude of 6.4. But when about 70 of our 100 stations forwarded already their data, we changed it to magnitude 5.4,” Alanis told the Philippine News Agency.

He issued the clarification after various reactions were posted by netizens on social media regarding the changing of the earthquake’s magnitude from 6.4 to 5.4.

Minutes after the temblor, Phivolcs’ website posted that the quake was measured at magnitude 6.4, adding that it was “expecting aftershocks”.

At 12:09 a.m. (Dec. 8), Phivolcs changed the post to magnitude 5.4. It was also inadvertently posted as “12:09 p.m.” instead of 12:09 a.m.

Alanis said the revision was the result of the final analysis of all the data that they received.

“Technically, we did not change it because it was wrong. But because more data had already come in and completed the needed inputs for the analysis,” he added.

The 5.4 magnitude temblor occurred at 10:37 p.m. and was traced 37 kilometers north of Prieto Diaz, Sorsogon with a depth of 77 kilometers.

No one was reported hurt and no property damage was reported as of this posting.

Source: Philippines News agency

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