The empirical formula determination of local magnitude for North Moluccas region

The energy of local and regional earthquake is usually expressed by local magnitude. In addition, local magnitude is also useful for seismic hazard assessment. The aims of this study are to determine the empirical formula of local magnitude and the correction distance function, -log A 0, applied for North Moluccas region. This study used waveform data from the MCGA seismic network located around North Moluccas region. We collected 148 maximum amplitude data of 40 earthquake events which are recorded by 6 seismometers with range of time from December 1, 2013 till January 31, 2014, hypocentral distance from 25km till 550 km, and depth below 70 km. The results of this study are the empirical formula of local magnitude, M L = log A + 0.651logR + 0.0037R 1.3568, and the correction distance function, logA 0 = 0.651logR + 0.0037R 1.3568, respectively. Also we found that the station correction values of the GLMI, LBMI, MNI, SANI, TMSI, and TNTI seismic stations were -0.057, -0.216, -0.322, 0.088, -0.494, and 0.180, respectively. Low amplification is indicated by the positive value of station correction; meanwhile high amplification is by the negative. The correction distance function of North Moluccas region is similar to the Central California region. It means that the attenuation characteristics of the two regions have similarities.