IMAGING 3D SEISMIC VELOCITY AROUND SOURCE REGION OF MW 6.5, DECEMBER OF 2016 – JANUARY OF 2017 PIDIE JAYA EARTHQUAKE FROM DOUBLE DIFFERENCE TOMOGRAPHY AND WAVEFORM CROSS CORRELATION

• Main Author: Kusuma Dewi, Rianty
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/23944
• Institution: Institut Teknologi Bandung

Pidie Jaya earthquake occured on 7th December 2016. It causes a lot of damage and 102 victims reported by National Disaster Management Authority (BNPB). According to Indonesian Agency for Meteorological, Climatological and Geophysics (BMKG), the main shock happened at 05:03:35 WIB in 5.29° north and 96.22° east with magnitude of 6.5 (depth of 15 km). A week after, research collaboration of ITB, Unsyiah, BMKG and GFZ Postdam Germany installed 9 seismometers around Pidie Jaya since 14th December 2017 to 16th January 2017. It has been identified that there were 302 of aftershock events. In this study, we have been conducting (i) determination of location of hypocenter using probabilistic grid searching method with NLLoc program, (ii) updating of 1D seismic velocity model using Joint Hypocenter-Velocity Determination (JHD) with Velest program, (iii) enhance of picked of P-and S-wave arrival time using waveform cross correlation method, and (iv) determining 3D Vp, Vs, and Vp/Vs structure in the region using tomography double difference method with program TomoDD. Tomography double-difference inversion gives the clearest image in 15 km depth. It has been identified the existence of fault with strike N45⁰SE in the depth 15 km.The structure of fault can be determined by the existence of the contrast between low velocity anomaly (red) dan high velocity anomaly (blue). The aftershock mostly happened in low velocity zone (red color). In this study we couldn’t find accurately the movement direction of the fault, so we need more study to find out the mechanism of the fault movement.