Looking back: The magnitude 6.9 earthquake in Negros Oriental
Twelve years ago, on Feb. 6, 2012, at 11:49 a.m., Negros Oriental and its neighboring islands were struck by a powerful 6.9-magnitude earthquake, followed by a series of immediate aftershocks.
to lateral spreading, undulation and ground subsidence. (Phivolcs)
Nine days later, the Philippine Institute of Volcanology (Phivolcs) reported 1,649 aftershocks recorded through its seismic monitoring network.
This seismic event, which occurred in February 2012 with its epicenter located five kilometers northwest of Tayasan, Negros Oriental, resulted in 51 deaths and 112 injuries, according to Phivolcs.
Based on the report released by the National Disaster Risk Reduction and Management Council (NDRRMC) on Feb. 20, 2012, the cost of damages to buildings, infrastructure, and properties amounted to P383 million.
Phivolcs stated, "The main shock and ensuing aftershocks have epicenters on the eastern coast of Negros Oriental, near the municipalities of Tayasan, Jimalalud, La Libertad, and the city of Guihulngan."
"The earthquake caused significant damage due to its shallow nature, with a focal depth of 10 kilometers," Phivolcs added.
Additionally, Phivolcs reported strong ground shaking, liquefaction, landslides, tsunamis, ground deformation, and coastal uplift.
Phivolcs also noted "severe" damages to infrastructure and houses in the municipalities of Ayungon, Tayasan, Jimalalud, La Libertad, and Guihulngan City, Negros Oriental.
"These towns experienced the strongest ground shaking on the PHIVOLCS Earthquake Intensity Scale (PEIS) VII-VIII (destructive-very destructive)," Phivolcs stated.
Moreover, local tsunamis with wave heights ranging from less than a meter to 4-5 meters (m) affected Ayungon, Tayasan, Jimalalud, La Libertad, and Guihulngan City, with "unusual" waves reported in the more distant city of San Jose in the south and Vallehermoso in the north.
"Unusual sea waves, minor landslides, small sinkholes, and slight damages to infrastructure and properties were also reported and documented in Badian, Moalboal, Ronda, and Dumanjug, Cebu," Phivolcs added.
According to Phivolcs, the United States Geological Survey (USGS), and the International Seismic Network (ISN), the tremor was tectonic and caused by a "dominantly thrust-faulting movement along a NE-SW fault plane."