Source Parameters Estimations of February 23rd and 24th, 2009 Nias Earthquakes Using Local Seismogram Analysis

Two earthquakes in Nias, North Sumatra have been investigated, which occurred on 23rd and 24th February 2009 at 05:56:34.3 and 12:13:15.8 UTC, respectively. This investigation was conducted to estimate the earthquake source parameter. Seismogram data that are used is a record of four surrounding stations, with epicentral distance below 10°. The analysed data are three components waveform. The method used to analyse the earthquake source parameter is a combination between waveform deconvolution iteration method and wave number discretization method for the local data. The resulted depth, seismic moment, slip, dip and rake and also moment tensor of earthquake sources using correlation between the measured seismogram and its synthetic which have a correlation and reduction variance in the values of 77.5% and 60.0%; and also 80.02% and 64.25%. This result showed that the earthquake source parameter estimation is suitable to describe earthquake source characteristic. The faulting pattern of the two events was a double couple inverse faulting.