Paleosiesmology of the
Masbate Fault
Kathleen
L. Papiona1,2 and Yoshihiro Kinugasa1
1Tokyo
Institute of Technology; 2 Philippine Institute of
Volcanology and Seismology
Introduction
Paleoseismic study through trench excavations is one of the most
effective ways in investigating earthquakes that is beyond the cover
of historical seismic records (McCalpin, 1996; Crone and Omdahl,
1987; Sieh, 1978; and Allen, 1975). The Philippine Fault, considered
as one of the most important and active structures along the
Philippine archipelago, has been the source of many destructive
earthquakes in the past. The central segment of the Philippine Fault
is the Masbate Fault, which generated a Ms 6.2 earthquake in 2003
accompanied by surface rupture that is mappable to about 23 km on
land (PHIVOLCS Quick Response Team, 2003; Abigania et al., 2003).
Besana and Ando (2005) through investigation of the occurrence of
earthquakes within historical and instrumental periods suggest that
strong and moderate earthquake occurred along the Masbate Fault and
that these earthquakes are usually accompanied by long ground
ruptures. Historical record in the Masbate region is short, covering
only around 30 years before the installation of seismic instruments
in the Philippines (Repetti, 1946, SEASEE, 1985; Bautista, 1996).
Hence, in order to assess the seismic history beyond the historical
records at the Masbate Fault, trench excavation would be necessary. |