- January 24, 2025
- Posted by: humanitarianweb
- Category: Humanitarian News
What is happening in Southern Leyte and its vicinity?
At 7:39 AM Philippine Standard Time (PST) on 23 January 2025 (Thursday), a moderate-sized earthquake with magnitude (MW) 5.8 shook the Province of Southern Leyte and adjacent provinces. The earthquake has an epicenter located 6 kilometers southeast of San Francisco, Southern Leyte, and an estimated depth of 11 kilometers (Figure 1). The earthquake is associated with the movement of a local active fault in the area. As of 1:30 PM PST on 23 January 2025, the DOST-PHIVOLCS Philippine Seismic Network (PSN) recorded a total of 73 aftershocks ranging from MS 1.6 to MS 2.9.
Using the PHIVOLCS Earthquake Intensity Scale (PEIS), the highest reported intensity is PEIS VI (Very Strong) which was felt in San Francisco, Southern Leyte (Annex 1. DOST-PHIVOLCS Earthquake Information No. 2). At PEIS VI, many people are frightened, and many run outdoors. Some people lose their balance. Motorists feel like driving with flat tires. Heavy objects or furniture move or may be shifted. Small church bells may ring. Wall plaster may crack. Very old or poorly built houses and human-made structures are slightly damaged though well-built structures are not affected. Limited rockfalls and rolling boulders occur in hilly to mountainous areas and escarpments. Trees are noticeably shaken.
Have strong to great earthquakes affected Southern Leyte and its vicinity in the past?
Yes. At least six (6) significant earthquakes with magnitudes ranging from M 5.9 to M 6.7 affected Southern Leyte and nearby provinces in Eastern Visayas and Caraga between 1917 and 2017 based on the historical records (SEASEE, 1985) and DOST-PHIVOLCS Earthquake Catalog. Some strong earthquakes (M>6) that affected Southern Leyte were the 1973 M 6.3, 1977 M 6.4, 1994 M 6.2, and 2017 M 6.7 events.
Why do earthquakes occur in the vicinity of Southern Leyte?
Southern Leyte and its neighboring provinces experience earthquakes as they are situated in one of the seismically active regions in the Archipelago. The presence of onshore and offshore active faults, particularly the Philippine Fault and its segments, generates high seismicity in the area. Additionally, there are local faults nearby, some potentially buried by recent deposits and have the potential to cause minor to strong earthquakes.
What can we expect from the current earthquake activity?
We can expect light to moderate aftershocks in the epicentral area. These aftershocks could persist for several days to months, and some may also be felt in nearby provinces.
Aside from moderate ground shaking, what other seismic hazards may be expected?
Earthquake-induced landslides, rock falls, and other types of mass movement may occur on sloping terrains, specifically in mountainous or hilly areas. Liquefaction effects manifested by subsidence, ground fissures, sand boils, lateral spreads, and/or flotation of buoyant structures may affect low-lying, water-saturated, and sandy areas near water bodies.
Did this recent earthquake event trigger a tsunami?
No. DOST-PHIVOLCS did not issue a tsunami warning. Although the epicenter of this earthquake is offshore, no destructive tsunami waves were generated because there was no significant vertical displacement of the seafloor. However, localized sea-level disturbances may be observed due to extreme ground shaking along the coasts.
Can this earthquake indicate volcanic activity?
No. The earthquake is tectonic in origin. However, DOST-PHIVOLCS will closely monitor earthquakes that may be associated with nearby active volcanoes. The nearest active volcano is the Cabalian Volcano, located approximately 25 kilometers north of San Francisco, Southern Leyte.
What should be done by the affected communities?
Communities should be prepared for aftershocks. In case of a strongly felt earthquake, it is recommended that people protect themselves by doing the “duck/drop, cover, and hold.”
People should be cautious of structures visibly weakened or having signs of damage caused by the magnitude 5.8 earthquake. These may be further damaged by succeeding earthquakes and injure building occupants. It is best to contact the concerned Municipal/City Engineering Office for building inspection. Civil engineers from the local government and other organizations are strongly urged to inspect buildings and infrastructures to determine structural integrity and recommend appropriate actions. Structurally compromised buildings should not be reoccupied until certified safe by structural engineers. In homes and offices, heavy furniture and appliances should be strapped to the walls, and hanging objects securely fastened to prevent them from causing injuries.
Mountain/hill slopes should be checked for tension/incipient cracks due to strong ground shaking. Tension cracks make slopes more susceptible to landslides, especially during heavy rainfall and/or aftershocks. Landslide-prone areas should be avoided.
Rumors that may cause panic are easily spread. Avoid sharing messages from unconfirmed and unreliable sources, and get information from DOST-PHIVOLCS and respective Disaster Risk Reduction and Management Offices (DRRMOs).
What is the role of DOST-PHIVOLCS?
DOST-PHIVOLCS conducts seismic monitoring and provides earthquake information. It operates and maintains a network of 121 seismic stations spread across the Philippines. The closest seismic stations to San Francisco, Southern Leyte are the staff-controlled seismic stations in Palo in Leyte, Surigao City in Surigao del Norte, Tagbilaran City in Bohol, and Lapu-Lapu City in Cebu, and satellite-telemetered seismic stations in Maasin City in Southern Leyte, Ormoc City in Leyte, Borongan City in Eastern Samar, Loreto in Dinagat Island, Garcia Hernandez and Talibon in Bohol, and San Francisco in Cebu.
DOST-PHIVOLCS will deploy a Quick Response Team (QRT) to the province of Southern Leyte. The QRT aims to assess geologic impacts and conduct information dissemination campaigns to allay the fears of the public. Furthermore, DOST-PHIVOLCS works hand-in-hand with other government agencies in mitigating the damaging effects of earthquakes.
Please visit our website at www.phivolcs.dost.gov.ph, Facebook (/PHIVOLCS), and X (@phivolcs_dost) for earthquake and tsunami information, volcano updates, hazard maps, and information materials. Earthquake observations may be reported to DOST-PHIVOLCS at telephone numbers (02) 8929-9254 and (02) 8426-1468 to 79, local 307 and 308, or via Facebook Page (direct message).
Minor earthquakes: M3 to 3.9; Light earthquakes: M4 to 4.9; Moderate earthquakes: M5 to 5.9; Strong earthquakes: M6 to 6.9; Major earthquakes: M7 to 7.9; Great earthquakes: M8.0 and above.
Download PDF: https://bit.ly/2024-SouthernLeyte-EQ