PHIVOLCS records over 9,000 aftershocks in Cebu

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported over 9,000 aftershocks following the magnitude 6.9 earthquake that struck Bogo City, Cebu, on September 30.

PHIVOLCS noted that 34 of the aftershocks are felt, with magnitudes ranging from 1.0 to. 5.1.

The agency says the number of aftershocks per day is decreasing, but these may continue for weeks to months as the subsurface adjusts to a stable condition.

“You would notice in the chart that the number of aftershocks per day (frequency) is decreasing,” PHIVOLCS said.

PHIVOLCS recommended a five-meter avoidance zone from the fault, traced to the Bogo Bay Fault in Sitio Looc, Barangay Nailon, to ensure public safety.

The agency emphasized that aftershocks are natural and expected when a major earthquake occurs, noting that the movement of the underground is still stabilizing.

“Aftershocks may persist for weeks to months. It means that the part of the subsurface that moved is still adjusting to a stable condition/position,” PHIVOLCS said.

The National Disaster Risk Reduction and Management Council (NDRRMC) confirmed that fatalities remain at 72, while 39,806 houses across Central Visayas are reported damaged.

Moreover, PHIVOLCS reported a 4.4 magnitude earthquake that struck Burgos, Surigao del Norte, at 12:58 pm on Tuesday, October 7.

Earlier the same day, a magnitude 4.9 earthquake also hit 51 kilometers northwest of Sipalay, Negros Occidental, at 8:04 a.m.

The tremor, with a depth of 10 kilometers, was felt at Intensity II in Iloilo City, while instrumental intensities were recorded at Intensity I in Bago City, Negros Occidental.

PHIVOLCS Director Dr. Teresito Bacolcol advised residents to consult municipal or city engineers before returning to damaged homes.

“If there are visible damages sa mga istruktura Kung saan sila nakatira, huwag muna silang pumasok,” Bacolcol noted.

“They have to consult their municipality or city engineers kasi kung hindi man ito totally na-damage during the main shock, baka ma-damage ito totally during a strong aftershock,” he added.