At 08:43 AM Philippine Standard Time (PST), 27 July 2022, a major earthquake with magnitude (Mw) 7.0 shook the provinces in northwestern Luzon and adjacent areas including Metro Manila. The earthquake has an epicenter located at 17.63°N, 120.63°E – 3 km N 50° W of Tayum (Abra) with a depth of 15 kilometers. The ground shaking was felt at PHIVOLCS Earthquake Intensity Scale (PEIS) VII (destructive) in Abra and as far as Camarines Sur at PEIS I (scarcely perceptible). Based on the location and focal mechanism, the earthquake was generated by the Abra River Fault with an oblique slip. The National Disaster Risk Reduction and Management Council (NDRRMC) reports that the earthquake caused 11 deaths, 574 injured and approximately Php 1.6 billion worth of damages to infrastructure and agriculture (NDRRMC SitRep 12, 7 August 2022).
The DOST-PHIVOLCS Quick Response Team (QRT) was immediately deployed on the same day as the earthquake to: 1) conduct earthquake information, education and communication activities to local government units (LGUs) and local residents in the affected areas; 2) assess and map the earthquake’s geologic impacts and effects to structures; 3) deploy temporary seismic stations for continuous aftershocks monitoring; 4) conduct intensity assessment; and 5) assist the LGUs in assessing selected evacuation/relocation sites in terms of earthquake hazards.
Most of the heavy structural damages were sustained in Abra and Ilocos Sur. Poor engineering and the use of substandard construction materials were the major contributing factors to the damages. Earthquake-induced landslides were documented in the mountainous areas of Abra, Ilocos Sur, Mountain Province, Kalinga and Benguet. Liquefaction occurred along the coastal areas in Ilocos Sur and in the river channels in Abra and Ilocos Sur. Sea level disturbance was also observed in some coastal areas of Ilocos Sur and La Union.
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