Moment tensor inversion implementation in determining focal mechanism solution of Palu-Koro and Matano fault events: processing strategy

Abstract Earthquake focal mechanisms are helpful in analyzing seismotectonic features in a specific area, as they can depict subsurface structures. Earthquake focal mechanism solution can result from the first polarity or moment tensor inversion method. The moment tensor inversion can produce complete information of focal mechanism solution than the first polarity method. However, the procedure is slightly more complicated, for it is based on waveform inversion. Several problems related to signal processing might arise. Strategies should be applied to overcome the difficulties and obtain reliable focal mechanism solutions. In this study, we used moment tensor inversion to produce focal mechanisms data of Palu-Koro and Matano Fault events. We processed the focal mechanism of events with a depth of less than 60 km and with a minimum magnitude of Mw 4.7. The moment tensor inversion is conducted using Isolated Asperities (ISOLA) software. Full waveform inversion of stations located near Palu-Koro and Matano Fault is applied. The cause of waveform fitting difficulties using the data in this study area and the solution are discussed. For instance, the existence of unseen signal noise and clear-yet-disturbing signals are observed. Improved solutions can be achieved by station reselection and bandpass frequency adjustment.