Mapping of the Inabanga Fault in Bohol, Philippines using High Resolution LIDAR Imagery and Field Mapping Verification
Authors / Editors: Felix, R., Norini, G., Eco, R. N. Lagmay, Alfredo Mahar
A Mw 7.2 earthquake devastated Bohol Island in the Central Philippines region on 15 October 2013 at 8:12 am. The temblor was associated with severe ground rupture, intense ground shaking and other earthquake hazards. Along with numerous landslides and sinkholes that formed during the event, the Bohol earthquake caused 222 deaths and massive destruction to infrastructure amounting to 1.64 million Philippine Pesos (US$38.21 million). The source of the main shock is from an unmapped reverse fault with slight strike-slip component. Ground rupture of the Bohol event is best exposed in Barangay (village) Anonang, Municipality of Inabanga where a fault scarp 3-m high, with mean principal orientation of N51°E is observed. Thousands of inland and offshore aftershocks were recorded, which plots on a general N55°E trend, defining a plane about 100 km long. Using a 1-m resolution digital terrain model (DTM) derived from a Light Detection and Ranging (LiDAR) airborne survey after the earthquake, lineaments were identified and validated through field mapping to define the extent of the inland portion of the earthquake source. Other lineaments within the northern portion of Bohol Island were identified using the Lidar DTM to map out other possible structures in the region that may have been responsible for significantly large aftershocks with strike-slip movement as defined by focal mechanism solutions. Pre-event, 5-m resolution IfSAR DTMs mapped in 2012, were also used to determine changes in morphology after the 2013 temblor, including the identification of older fault scarps in Inabanga, where the newly-formed fault scarp is now seen. Results of this work can be used as reference for future studies to understand the tectonics of Bohol Island and the fatal 15 October 2013 earthquake to mitigate the impacts of future earthquake hazards in the area.
Published by: Proceeding of the 5th International INQUA Meeting on Paleoseismology, Active Tectonics and Archeoseismology , 2014 |
Page Nos: 66-69
Type of Publication: Conference Paper