SEISMIC HAZARD FUNCTION (SHF) STUDY PRIOR TO LARGE EARTHQUAKE EVENT OF THE YEAR 1994 AND 2006 OFF COAST OF THE JAVA ISLAND: THE SHF ANALYSIS BASED ON THE CHANGE OF THE B-VALUE

The seismic hazard function analysis around the off coast of Java Island is investigated based on the changes of the b-value using the shallow crustal earthquake catalog data from 1963 to 2016. The study areas took place around M7.8 in 1994 and M7.7 in 2006. The change of the b-value is estimated using the maximum likelihood method with a constant number. First, the b-value surrounding the center area of interest with a radius of about 150 km is calculated based on the earthquake catalog data from 1963 to 2016 (b50). Second, the b-value based on five years with a one-year moving window (b5) is estimated before M7.8 in 1994 and M7.7 in 2006. The b5 is calculated based on the constant number of events of 25, 50, 75, and 100, and we evaluate the mean b-value. Furthermore, the SHF of b50 and b5 are calculated, and then they are compared. The results showed that the Probability of Exceedance (PE) of SHF b5 increased by about five years before the two large earthquake events. Therefore, the results obtained in this study might be very beneficial for earthquake mitigation and modeling efforts for the possible potential of the earthquake hazard study and future analysis.