The Philippine Institute of Volcanology and Seismology (Phivolcs) has so far recorded over 3,200 aftershocks following the magnitude 7.0 earthquake that struck Tayum, Abra on July 27.
As of 8 a.m., Monday, Aug. 8, Phivolcs had detected 3,235 aftershocks, with magnitudes ranging from 1.4 to 5.1.
Of the recorded earthquakes, 977 earthquakes have been plotted by three or more stations.
Phivolcs said 63 of these tremors were felt.
The 7.0-magnitude earthquake, which struck Abra at 8:43 a.m. on July 27, had shook the provinces in northwestern Luzon and adjacent areas, including Metro Manila.
Phivolcs said the northwestern Luzon is one of the seismically active regions in the country because of the presence of active faults that include the northern segments of the Philippine Fault, Abra River Fault, West Ilocos Fault System, and Naglibacan Fault.
It also noted that there are other nearby local faults, some of which may now be covered by recent deposits, and offshore active faults that are potential sources of minor to strong earthquakes.