At 08:28 PM Philippine Standard Time (PST), 15 January 2023, a moderate earthquake with magnitude (MS) 5.3 shook Leyte Province and adjacent islands. The earthquake had an epicenter located at 11.33°N, 124.54°E – 7 km S 55° E of Leyte, Leyte with a depth of one (1) kilometer. The ground shaking was felt at PHIVOLCS Earthquake Intensity Scale (PEIS) VI (very strong) in Leyte, Leyte and as far as Bogo City, Cebu at PEIS I (scarcely perceptible). Based on the epicenter, focal mechanism, and actual field observations, the earthquake was generated by the Leyte Segment of the Philippine Fault. The National Disaster Risk Reduction and Management Council (NDRRMC) reported that the earthquake caused 18 injured persons and damaged 434 houses and 26 infrastructure (NDRRMC Progress Report 3, 26 January 2023).
The DOST-PHIVOLCS Quick Response Team (QRT) was deployed from 26 to 31 January 2023 to: 1) conduct earthquake information, education and communication activities with 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) retrieve peak ground acceleration (PGA) data from the Philippine Strong Motion Network (PSMNet); 4) conduct intensity assessment; and 5) assist the LGUs in assessing selected evacuation/relocation sites in terms of earthquake hazards, if deemed necessary. The Seismological Observation and Earthquake Prediction Division (SOEPD) monitored the earthquake aftershocks, and an office support team assisted in data compilation and map generation during the field investigation.
Most of the damages to structures were sustained in Leyte, Leyte. Poor engineering practices and the use of substandard construction materials were the major contributing factors to the damages. Some of the building and infrastructure damages were also caused by the ground rupture of the Philippine Fault – Leyte Segment. Earthquake-induced landslides were documented in Brgys. Calaguise and Palid Uno in Leyte, Leyte. Liquefaction is limited on the marshlands of Palaypay District in Brgy. Poblacion, Leyte, Leyte. Analysis of the seismic waveform and recorded PGA value in Brgy. Poblacion suggests that the site amplification of the ground motion was influenced by the subsurface geology of the area.
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