Implementing and evaluating an automatic centroid moment tensor procedure for the Indonesia region and surrounding areas

The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor (CMT) automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas. Gisola software was used to estimate the CMT solution by selecting the velocity model that best suited the local and regional geological conditions in Indonesia and the surrounding areas. The data used in this study were earthquakes with magnitudes of 5.4 to 8.0. High-quality, real-time broadband seismographic data were provided by the International Federation of Digital Seismograph Networks Web Services (FDSNWS) and the European Integrated Data Archive (EIDA) Federation in Indonesia and the surrounding areas. Furthermore, the inversion process and filter adjustment were carried out on the seismographic data to obtain good CMT solutions. The CMT solutions from Gisola provided good-quality solutions, in which all earthquake data had A-level quality (high quality, with good variant reduction). The Gisola CMT solution was justified with the Global CMT (GCMT) solution by using the Kagan angle value, with an average of approximately 11.2°. This result suggested that the CMT solution generated from Gisola was trustworthy and reliable. The Gisola CMT solution was typically available within approximately 15 minutes after an earthquake occurred. Once it met the quality requirement, it was automatically published on the internet. The catalog of local and regional earthquake records obtained through this technology holds great promise for improving the current understanding of regional seismic activity and ongoing tectonic processes. The accurate and real-time CMT solution generated by implementing the Gisola algorithm consisted of moment tensors and moment magnitudes, which provided invaluable insights into earthquakes occurring in Indonesia and the surrounding areas.