Source Mechanism Analysis By Using Tensor Moment Inversion (Study Case : Pidie Jaya Earthquake in 2016 December 7th)

The earthquake event with M 6.7, on 7th December 2106 in Pidie Jaya, inflicted heavy casualties and material losses. In 1967, an earthquake event occurred near Pidie Jaya with M 6.1 which caused by Samalanga fault. However, the Pidie Jaya earthquake, although very close, but was not caused by the Samalanga fault activity. The latest, an unkown fault was considered as an active fault and the location of earthquake sources and and a part of the branching of Samalanga fault. It is very interesting to discuss, generally earthquake in Aceh, always happen on Sumatera fault's path. Analysis of earthquake source mechanism is very important to do, to know the fault characteristic and direction. The analysis in this study involves inversion of tensor moments with isola program on each recording component, which will provide a synthetic wave as a comparison. The earthquake mechanism which obtained from the inversion is strike-slip with left-lateral and has the parameter strike 254 degrees, dip 80 degrees, and rake 48 degrees on the first nodal plane as the true nodal. While, the second nodal has the plane parameter is strike 153 degrees, dip 42 degrees, and rake 165 degrees. From these parameters, the first nodal plane that has a strike 153 degrees is considered to be interpreting the new fault line as it is also followed by the direction of the spread of aftershocks. These result indicate that the Samalanga Fault is not the cause the Pidie Jaya earthquake, and shows the real direction of Pidie Jaya fault from South-West to North-East with lef-lateral orientation.