Philippine Standard Time

A strong earthquake with a magnitude (Mw) 6.6 struck Masbate at 8:03 AM Philippine Standard Time (PST) of 18 August 2020. The hypocenter was located 7 km S29E of Cataingan, Masbate with a depth of 21 kilometers. The focal mechanism from DOST-PHIVOLCS Swift-CMT solution indicates strike-slip faulting associated with the left-lateral movement of the Masbate segment of the Philippine Fault. This earthquake was preceded by several foreshocks (pink dots) including the M4.9 and M4.6 earthquakes on August 11 and 17, respectively. As of 10:30 am of 19 August 2020, there are already more than 200 aftershocks (blue-green dots) recorded including the M5.1 earthquake. Masbate had also experienced a strong earthquake last 2003, which produced a 23-km long surface rupture. The 2003 Masbate earthquake also recorded foreshocks similar to the recent event (PHIVOLCS, 2003).

The Masbate segment of the Philippine Fault is characterized by the occurrence of frequent moderate-sized earthquakes, some of which are accompanied by surface ruptures (Besana and Ando, 2005).