Disaster mitigation

[DM-05] Comparison of Seismic Tomography and Full Waveform Inversion in Describing The Earthquake Vulnerability Zone in Sumatera Island, Indonesia

*Indriati Retno Palupi¹, Wiji Raharjo¹ (1. UPN "Veteran" Yogyakarta (Indonesia))

Indonesia is located between some tectonic plates, they are Eurasia, Australia, and the Pacific. Some earthquakes with big magnitude have ever hit, like Aceh's Earthquake and Tsunami in 2004. It is located in Sumatra, the western island of Indonesia. There are many earthquake sources in Sumatra, make it include as one of the most vulnerable zones of Indonesia. It has high seismicity based on the earthquake catalog of USGS information. The vulnerability zone usually associates with a low-velocity anomaly in Tomography. The Tomography is done in some certain layer based on the number of the hypocentre in some depth with BMKG seismic station around Sumatera. Arrival time is calculated between the hypocentre and the station with AK 135 as a velocity initial model. Straight forward ray tracing is chosen as the simplest way in modeling the Tomography. Based on the Tomography result, some low-velocity zone is associated with earthquake sources around Sumatera like the Semangko Fault and the Subduction zone, but not clearly, especially in the earthquake source boundary. Then, it is used as an initial model in Full Waveform Inversion to get a better description. Good grid size is very important in the process. Full Waveform Inversion uses the finite difference method to improve the velocity model of Tomography over and over in its iteration. However, the Full Waveform Inversion result is better to describe the vulnerability zone of Sumatera.