IJASEIT

International Journal on Advanced Science, Engineering and Information Technology, Vol. 12 (2022) No. 3, pages: 892-898, DOI:10.18517/ijaseit.12.3.12488

Hypocenter Determination and Estimation 1-D Velocity Models Using Coupled Velocity-Hypocenter Method

Widya Utama, Sherly Ardhya Garini

Abstract

Hypocenter relocation is performed to obtain a high-precision hypocenter location (accurate earthquake location). An accurate earthquake location is the key problem in seismology. Further information from an accurate hypocenter location can be used for seismicity analysis, velocity structure study, and earthquake prone mapping as one of the earthquake mitigation efforts. In this research, the method used to relocate the earthquake hypocenter was the Coupled Velocity-Hypocenter. Relocations were conducted in the Central Sulawesi region; we located 40 local earthquake events with a magnitude of ≥ 3.8 ML and a depth of ≤ 25 km. The selected P-wave traveltimes were inverted from 5 seismic stations. The variance of initial velocity models used the 1-D Primary wave velocity model of North Sulawesi, Jeffrey-Bullen and Central Sulawesi. The relocation results show that most of the hypocenters are concentrated precisely in minor faults present in the research area, and the hypocenter distribution of the events indicated as destructive shallow earthquakes occurs at depths of about 5-15 km. The residual distributions resulting from the relocation using the initial velocity model of the Central Sulawesi region indicates an improved quality if compared to Jeffrey-Bullen velocity model and the North Sulawesi velocity model, with RMS error value of 0.08 seconds. This research concluded that the 1-D velocity model in the regional (Central Sulawesi Region) reference was suitable for determining the high-precision hypocenter location.