The Province of Cebu has three probable fault lines that could generate earthquakes in the island, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).
During his presentation at the provincial board (PB) session last October 21, Jeffrey Perez, Philvolcs supervising science research specialist, cautioned that the province should prepare for its eventual rupture.
Perez presented the possible local locations of the three fault lines in its hazard map, which was taken using overhead satellite imagery.
He said they would look for and use aerial photographs to clearly identify the exact locations of the fault lines as what they did in identifying the others in the country.
In the hazard map, two of the traces of the fault lines are in the interior parts of the south. They are situated opposite to each other while the other one is located somewhere in Central Cebu.
There are no traces of faults lines in the north but it does not mean the area is safe. Perez said the locality could still be hit by the impact of the quake caused by other fault lines in other areas. This is what is happening in Cebu after the faults in Bohol and Negros Oriental (last year) moved.
PB Member Jose Ribomapil Holganza, Jr., asked if there is a device that can be placed in the ground to spot the exact location of the fault.
“There are geophysical instruments that can be used but these are expensive,” answered Perez.
Aside from ascertaining the exact location of the faults, Phivolcs is also studying the strength of the ground shaking these faults can cause.
Perez also dismissed the forecast of an 8.0 Magnitude quake that circulated through text messages. He reiterated that there is no instrument yet that would enable anyone to forecast an earthquake.
Phivolcs can only monitor the movement of the active faults following its outbreak but it cannot predict the occurrence quakes, he said.
Perez also contradicted the belief that Cebu will not be affected by Tsunami because the island is located in the interior part of the archipelago. He said, depending on the magnitude of the quake, Tsunami can wrap an entire island.
When there is a Tsunami warning, the people should evacuate to a higher location of at least 10 meters from the sea level.
The recent 7.2 magnitude quake in Bohol did not generate Tsunami because the epicenter is not in the ocean. The epicenter is six kilometers southwest of Sagbayan, Bohol and 12 kilometers in depth. (Xerxes Alkuino)