February 6, 2012 Earthquake: Negros Oriental Province, Philippines

At least 51 people killed, 112 injured, 62 missing, 23,000 displaced, about 15,000 buildings destroyed or damaged, at least 17 bridges and many roads destroyed or damaged and utilities disrupted on Negros. Many landslides occurred including two that buried 100 homes at La Libertad and 30 homes at Guihulngan. Large waves reported at La Libertad. Some buildings damaged and landslides occurred on Cebu and utilities disrupted at Iloilo, Panay. Estimated 15 million U.S. dollars damage on Negros and Cebu. Felt (VII PIVS) at Dumaguete, Guihulngan, Tayasan and Vallehermoso and (VI PIVS) at La Carlota, La Castellana, Manjuyod and Tanjay, Negros. Felt (VI PIVS) at Clarin, Bohol and at Argao, Barili, Cebu City and Dalaguete, Cebu. Also felt (VI) at Moalboal, Cebu. Felt throughout the Visayan Islands, in much of Mindanao and as far as the Manila area, Luzon.

The broad-scale tectonics of the Philippine Islands are dominated by the west-northwest convergence of the Philippine Sea plate with respect to the Sunda plate. This motion, about 10 cm/year at the latitude of the earthquake of February 6, 2012, is accommodated by subduction along the east and west sides of the Philippines Archipelago and by motion of microplates and distributed deformation within the Archipelago. The February 6 earthquake occurred as thrust-faulting within the archipelago. Several earthquakes similar in size to the February 6 earthquake occurred within the archipelago in eastern Negros, Cebu, and Bohol in the twentieth century. In 1948 a magnitude 8.1 earthquake occurred about 150 km to the west of the February 6 earthquake in a zone of shallow seismicity that is associated with subduction along the Negros Trench on west side of the Philippines Archipelago.

At least 51 people killed, 112 injured, 62 missing, 23,000 displaced, about 15,000 buildings destroyed or damaged, at least 17 bridges and many roads destroyed or damaged and utilities disrupted on Negros. Many landslides occurred including two that buried 100 homes at La Libertad and 30 homes at Guihulngan. Large waves reported at La Libertad. Some buildings damaged and landslides occurred on Cebu and utilities disrupted at Iloilo, Panay. Estimated 15 million U.S. dollars damage on Negros and Cebu. Felt (VII PIVS) at Dumaguete, Guihulngan, Tayasan and Vallehermoso and (VI PIVS) at La Carlota, La Castellana, Manjuyod and Tanjay, Negros. Felt (VI PIVS) at Clarin, Bohol and at Argao, Barili, Cebu City and Dalaguete, Cebu. Also felt (VI) at Moalboal, Cebu. Felt throughout the Visayan Islands, in much of Mindanao and as far as the Manila area, Luzon. (reference #1053)

9m USD total damage (reference #13034)

The epicenter was located by the Philippine seismic network at 9.97° N, 123.14° E, which is approximately 5 km northwest of Tayasan, Negros Oriental. The earthquake had a depth of focus of 5-10 km. Based on the hypocenter and focal mechanism solutions by the International Seismic Network (ISN), PHIVOLCS and the United States Geological Survey (USGS), the earthquake was determined to be tectonic in origin, and suggests a dominantly thrust-faulting movement along a NESW fault plane (Figure 2). The 06 February 2012 earthquake that hit Negros Oriental produced: (1) strong ground shaking, (2) liquefaction, (3) landslides, (4) tsunamis, and (5) ground deformation and coastal uplift. Considerable to severely damaged infrastructures and houses were observed in the municipalities of Ayungon, Tayasan, Jimalalud, La Libertad, and Guihulngan City in the province of Negros Oriental […] As of 13 February 2012, the National Disaster Risk Reduction and Management Ccouncil (NDRRMC) website posted the total cost of damages to roads, bridges and public buildings in Negros Oriental alone at Php346, 459, 000.00. (reference #13969)