Courtesy of TeleRadyo
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Movement from the Cotabato Trench caused the Magnitude 6.8 earthquake that rocked Davao Occidental Friday, the Philippine Institute of Volcanology and Seismology said.
Phivolcs chief Teresito Bacolcol said the agency revised its initial estimate of magnitude 7.2 to magnitude 6.8 after receiving more data from Phivolcs stations.
Phivolcs said the quake struck at a depth of 72 kilometers, with epicenter at 34 km northwest of Sarangani Island.
"This is much better than a strong earthquake na shallow," Bacolcol said in a TeleRadyo Serbisyo interview.
He added: "The deeper the earthquake, the less the energy that would be felt on the surface kasi the seismic waves would travel longer distances and nadi-dissipate 'yung energy."
In the interview, Bacolcol said the Cotabato Trench is the same earthquake generator that caused the 1976 Moro Gulf earthquake, considered the largest tsunamigenic earthquake to have occurred in Mindanao in recent decades.
“Ang gumalaw would be the Cotabato trench. It’s the same earthquake generator during that time 1976. There was a magnitude 8.1 earthquake. Ang nangyari that was 1976 August 17, may 8,000 casualties kasi nagkaroon ng tsunami and tsunami waves arrived 5 minutes after the earthquake and it happened past midnight kaya naka-contribute yan doon sa taas ng casualties,” he said.
Bacolcol, however, said Phivolcs does not expect the latest quake to cause a tsunami.
"Walang tsunami threat sa Mindanao...Hindi tayo mag-eexpect ng tsunami," he said.
He urged residents in affected areas to check their homes or buildings for damage before returning.
"Kapag may nakita silang visible damage dun sa bahay nila or sa building, huwag muna silang pumasok. They have to consult municipal or city engineer kasi baka hindi ito nasira during the main shock kapag meron strong aftershock mag-collapsed so as a precaution huwag muna silang pumasok and they have to consult a civil engineers," he said. - with a report from Johnson Manabat, ABS-CBN News