DUMAGUETE CITY – The series of earthquakes in Valencia, Negros Oriental is waning with only a few minor tremors recorded over the weekend, according to the Philippine Institute of Volcanology and Seismology (Phivolcs) seismic monitoring station in nearby Sibulan town.
Engr. Jose Molas, science research specialist who heads the local Phivolcs, this is an indication that the earthquakes are slowly disappearing since the time of the Magnitude 4.7 tremor recorded last January 27.
The Phivolcs central office had described that particular earthquake late last month, with a reference point in nearby Dauin town, as the “main shock”, with the smaller preceding quakes on the same day as “foreshocks.”
In the following days, many earthquakes were reported and recorded in Valencia town.
According to Molas, records at the seismic station in Sibulan show that two small earthquakes were recorded each on Saturday and Sunday.
The other week, though, the highest number of earthquakes recorded in one day in Valencia was at 28 between 8 a.m. of Feb. 1 and 8 a.m. of Feb. 2, Phivolcs records showed.
Thereafter, Engr. Molas said the succeeding earthquakes each day were recorded as follows: Feb. 2 with four; Feb. 3 with four; Feb. 4 with 14; Feb. 5 with five; and Feb. 6 with four.
On Feb. 7 and 9, no earthquakes were recorded while on Feb. 8, there was one tremor that occured, Molas said.
But these were small and weak tremors and Molas could not even give a magnitude or the size for each of them because according to him, these could not be computed by his office, being “local” tremors.
This is an indication that the ground shaking was slowly decreasing, Molas said.
As to whether Phivolcs main office would still send a team with the necessary instruments over to check on the seismic events in Valencia, Molas could not give a definite answer.
It would depend on the availability of personnel and the equipment, he pointed out.
Earlier, Phivolcs’ Seismological Observation and Earthquake Prediction Division (SOEPD) had assured that the agency would send a team over to determine the cause of the continuous ground shaking.
Meanwhile, Molas stressed that earthquakes happen everywhere and every day and they cannot be predicted.
Thus, even with what appears to be waning of the “aftershocks” of the main event last January 27, no one can tell if another earthquake will occur in Valencia or anywhere in Negros Oriental, he added.
As to the observations made by Professor Francisco Ablong, Jr., the head of the Physics Department of Silliman University in Dumaguete City, that the earthquakes were not tectonic but volcanic in origin, Molas declined to comment.
Ablong had said that he based his observations on Phivolcs data and these show that the recent earthquakes were a result of volcanic activity, specifically magma rising from underground, at the base of the Cuernos de Negros.
The Cuernos de Negros, popularly known by its local name Mt. Talinis, is a potentially active volcano as categorized by the Phivolcs and is largely in Valencia, where most of the series earthquakes in the past weeks have occurred. (Mary Judaline Partlow/PNA)
