The Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday said a fault that had not produced a powerful tremor in the past 400 years could have triggered the deadly 6.9-magnitude earthquake that jolted Cebu on Tuesday night.
Phivolcs Seismological Observation and Earthquake Prediction Division chief Dr. Winchelle Ian Sevilla said the epicenter of the tremor had not experienced a strong quake in four centuries based on the agency’s database.
Sevilla said only quakes of magnitudes 4 and below had been recorded in the affected areas. A team will be sent to the quake’s epicenter to gather more information about the tremor.
Phivolcs warned of more aftershocks in the next few weeks and months in light of the latest seismic event.
“We expect there will be more aftershocks in the next few days. Sometimes, the aftershocks would last for several weeks,” Phivolcs Director Dr. Teresito Bacolcol said.
The state seismic agency initially measured the quake at magnitude-6.7 but later adjusted it to 6.9 after validation, consistent with the findings of the US Geological Survey (USGS).
Phivolcs later issued a tsunami advisory, warning the residents Leyte, Cebu and Biliran to “stay away from the beach and not to go to the coast” due to strong currents and rapid changes of seawater level. It lifted this warning by 1:20 a.m. on Wednesday.
As of this writing, geologists recorded a total of 611 aftershocks in the affected localities since the main tremor. The powerful quake struck Bogo City, Cebu at 9:59 p.m. on Tuesday, September 30. It had a depth of five kilometers and was tectonic in origin.
