|
Summary of the
event:
Ma. Leonila P. Bautista and et al.
The
earthquake occurred on March 6, 2002 at 05:15 am (local time).
Its epicenter as located by PHIVOLCS is at 6.1 N; 124.0 E; 81 km or
about 81 km SW of Isulan, Sultan Kudarat.
PHIVOLCS computed its depth of focus at 15 km.
Its surface magnitude was computed by the Pacific Tsunami Warning
Center as 6.8 while its moment magnitude (Mw) and body wave magnitude (mB)
were computed by the the U.S. Geological Survey (USGS) as 7.2 and 6.3,
respectively. Based on the
earthquake location and mechanism solutions, its source is attributed by
PHIVOLCS to subduction along the Cotabato Trench.

Fig 1. Shows the PHIVOLCS earthquake
bulletin for this event.
As of March
9, 2002, the Office of Civil Defense (OCD) records show that 8 people had
died and 41 were injured due to the earthquake.
It affected 7,684 families in the provinces of Sultan Kudarat,
Sarangani, North Cotabato and South Cotabato including four cities and 17
municipalities (OCD Memorandum dated March 9, 2002).
The quake damaged 4 road networks, 7 bridges, 36 school buildings,
29 business establishments, 1 megadike, 2 health centers and 17 public
buildings. Damage amounted to
4.175 million pesos or about 80,000 US dollars.
The focal
mechanism as determined by Harvard University (Figure 2a) is
underthrusting along a NW-trending plane with minor strike-slip component.
The strike conforms to the established trend of the trench.
The USGS's solution for the event (Figure 2b) shows an almost
similar mechanism with a slightly larger strike-slip component than the
solution of Harvard University.

Fig 2a. Focal Mechanism of the earthquake
as determined by Harvard University

Fig 2b. Focal Mechanism of the earthquake as determined by USGS.
PHIVOLCS, 2002
Seismological Observation and Earthquake Prediction Division
|