Focal mechanism and source determination of the Padang Lawas earthquake april 30, 2020, using moment tensor inversion

The earthquake focal mechanism is one of the essential parameters in understanding characteristics an source. For example, mainshock at Padang Lawas Regency and South Tapanuli on April 30, 2020, caused some damage to houses, schools, mosques, especially Regency. BMKG released first information that was 1.17N, 99.53E, 24 kilometers northwest Lawas, North Sumatra province, a depth 10 kilometers, Thursday (30/4/2020) 15.20.25 Local Time with magnitude 5.6. purpose this study determine 2021, fault nodal plane best suits local tectonic conditions. We used moment tensor inversion method by using waveform velocity data from mini regional station seismic network installed 2019 close epicenter, namely TTSM, PLSM, LTSM, RRSI. also model AK135. In study, we applied filter technique Butterworth bandpass lower limit 0.05 Hz, upper 0.10 cut frequency 0.13 Hz. result shows variance observation calculation 0.3824. source show Nodal I strike/dip/slip values 100.1/88.3/7.5 II 9.9/82.5/178.3. value Seismic Moment (Mo) 0.4653E+17 Nm or Mw 5. Based distribution aftershocks pattern it consistent II. form strike-slip corresponds movement Sumatran system Toru segment. Therefore, conditions southern part are classified as active. Thus, government society need be aware make mitigation efforts against impact next future.