Stress Triggering Among Mw>6.0 Significant Earthquakes In Manokwari Trough

摘要

Earthquake doublet with moment magnitude 7.7 and 7.4 shook the Bird's Head of Papua Island on January 3~(rd), 2009. This event is the largest earthquake occurred in Manokwari Trough subduction zone. Coulomb stress changes analysis was conducted to show that this earthquake occurred as a result of triggering process by previous significant earthquake events. Source mechanisms was retrieved from Global Centroid Moment Tensor (GCMT) in the form of two nodal plane parameters for each earthquake. Determination of the actual nodal plane was performed by analyzing tectonic setting on research area and the distribution of aftershocks analysis which had previously been relocated using Modified Joint Hypocenter Determination (MJHD) method. The results show that positive coulomb stress changes of the present earthquake area can trigger the other future earthquakes. Instead negative coulomb stress changes of the area indicates that it has released stress. There are four interrelated significant earthquake events since 2001 with Mw>6.0 which expected to trigger big earthquakes in 2009. Analysis of earthquakes interaction in Manokwari Trough areas indicates that the location of the following earthquake is within the area of increasing coulomb stress by previous earthquake with the value ranging between 0.1 to 1 bar.