THE public must always be prepared for strong earthquakes up to magnitude 8.2, the head of the Philippine Institute of Volcanology and Seismology (Phivolcs) has warned.
“The Manila Trench and the Philippine Trench are both capable of generating magnitude 8.2 earthquake,” Phivolcs Director Teresito Bacolcol told the Philippine News Agency in an interview Sunday night.
He added that the Philippine Fault Zone in Gabaldon, on the other hand, is capable of generating a magnitude 7.9 earthquake.
Last Saturday night, a magnitude 7.4 earthquake shook Surigao del Sur and parts of Mindanao. The quake’s epicenter was traced 29 km. northeast of Hinatuan.
The earthquake has so far generated 1,898 aftershocks with magnitudes 1.4 to 6.6 as of 1 p.m. Monday.
At least 355 of these aftershocks were plotted or located, while 19 were felt.
Bacolcol said the strongest quake in Mindanao was the magnitude 8.1 on August 17, 1976.
“It (strongest quake) was generated by the Cotabato Trench. Around 8,000 people died because of the tsunami,” he said.
Bacolcol reiterated that the public should always be prepared.
“The country is part of the Pacific Ring of Fire, and every now and then we will be jolted by major earthquakes. Earthquakes are random events and we should always be prepared for these geological hazards,” he pointed out.
Meanwhile, Bacolcol said aftershocks from the magnitude 7.4 earthquake are not expected to cause a tsunami.
He explained that earthquakes with magnitudes 7 and above could cause a tsunami if they are shallow and if they happened offshore.
“For a magnitude 7.4 earthquake, the maximum expected magnitude aftershock would be around 6.4,” he continued.
Bacolcol also said that the magnitude 7.4 quake last Saturday did not cause much damage due to its depth.
“It was 26 km. deep, so the seismic energy was dissipated as it traveled to the surface,” he said. Philippine News Agency