THE Philippine Institute of Volcanology and Seismology (Phivolcs) said it has not issued a warning that a "bigger earthquake" will hit Negros Oriental following the series of tremors experienced by residents.
Ishmael Narag, who heads the Seismological Observation and Earthquake Prediction Division of Phivolcs, made the assurance in a phone interview Monday, February 5, as residents of Valencia, Negros Oriental, and other nearby areas have expressed concern, while others have panicked due to the report.
Others complained that the report, which circulated on social media last week, is causing confusion because of the conflicting statements of Phivolcs officials.
But Narag said there is no cause for alarm.
He said the Phivolcs is closely monitoring and analyzing data as to the probable cause of the “surge” of earthquakes of various magnitudes over the past weeks, mostly recorded in Valencia town but some with a reference point in nearby Dauin town.
The strongest one was recorded at magnitude 4.7 in Dauin last January 27 and was felt in Dumaguete City and Sibulan at Intensity 4. Other tremors varied in magnitudes, mostly less than magnitude 3, Phivolcs records show.
As of Monday morning, February 5, the local Phivolcs seismic monitoring station in Sibulan, Negros Oriental, headed by Engr. Jose Molas, reported more than 100 tremors since January 1.
The most number of earthquake events within one day was pegged at 28, recorded between 8 a.m. of February 1 and 8 a.m. of February 2, Molas said.
More tremors were recorded over the weekend, with at least eight events as of Monday morning.
While Molas initially described this as an “earthquake swamp,” his superior, Narag, said the Phivolcs could not be conclusive yet on this one because the “surge” of tremors in the past several days does not quite fit the definition of an earthquake swamp.
Besides, Phivolcs is also analyzing data to determine whether the January 27 strong tremor was the main shock, and the succeeding tremors were aftershocks, while the quakes that took place on the same day but at an earlier time were foreshocks, Narag said.
He said they believe that the earthquakes, which they describe as tectonic in origin, are taking place in the Sibulan fault line, which leads to the southwest of Negros Oriental.
Narag also said they do not believe that the earthquakes are volcanic in nature, although it is another department in the said agency that can validate this.
As to Phivolcs sending teams and instruments to Valencia to do a study of the earthquakes, Narag said it is not possible at this time because these are currently deployed in Bicol due to the eruption of Mayon volcano.