Leytes fault line

Philippine Institute of Volcanology and Seismology have marked 4 towns in Southern Leyte as earthquake high risk areas.

The towns of Sogod, Libagon, Saint Bernard and San Ricardo are right along the active Central Leyte Fault line which starts from Villalon, Leyte and ends in San Francisco, Southern Leyte.

The Central Leyte Fault line is part of the Philippine Fault Zone which extends throughout the country and is estimated to be

1,200-kilometers long. Significant reading in subterranean activity in the area was recorded on 1998 and 1991.

The PHIVOCS is imploring all local governments to really study their respective geological hazard maps carefully before starting any public works projects or approving private building constructions.

The National Disaster Coordinating Council admits that the national government is presently ill equipped to immediately handle such disasters, and that the best way to prevent widespread casualty and damage to property, was to convince local governments to be more responsible and residents to be more vigilant.

It also requested residents there to refer to the new geo-hazard maps before choosing and buying private property.

The central Philippine Fault Zone is found to be the locus of great earthquakes, a transition zone with slow

slip and creep activity. This is based on the analysis and correlation of seismic historic data and detailed

documentation of recent seismic events in the region. Based on this study the Guinyangan fault is defined to

be the northern locked portion with recurrence interval of as short as 65 years.

The Masbate fault is the centralpart with large and medium earthquakes accompanied by unusually large ground rupture. The north Central Leytefault and the south Central Leyte fault, on the other hand, are characterized by aseismic creep and medium-sized

events, usually with clusters of foreshocks, respectively. Unusual seismic activity both on the Masbate fault and

Central Leyte fault somehow correlates well with the behavior of known slow events and creep activity.

Furtherinvestigation of this region could lead to deeper understanding of impending major earthquakes, especially along

the Guinyangan fault, which usually produces larger damaging events, and for further understanding of the impact

of slow events and creep on the adjoining active structures.

Key words: Philippine Fault Zone (PFZ), historical earthquakes, slow events, creep, Masbate fault, transition

zone, Guinyangan fault, Leyte fault.