The Principal Stress Analysis of Matano Fault From Focal Mechanism Inversion
Asyer Octhav (a*), David P. Sahara (b), Dian Kusumawati (b)

a) Magister of Earth Science, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Indonesia
b) Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Indonesia

Abstract

The Matano Fault is an active left lateral strike slip fault located in Sulawesi as continuation segment of the Palu Koro Fault that separate Makassar Block from the North Sula Block. Many published studies revealed that the focal mechanism parameter can be used as useful information to estimate the principal stress orientation of an existing fault. We utilized the new moment tensor catalogue of Sulawesi which were produced from waveform inversion. We selected twenty five good waveform fitting solution. The solution composed of shallow earthquakes from 2009 to 2018 at Matano Fault and adjacent regions. We used the mechanism solution as input data in stress inversion method to calculate its principal stress orientation using STRESSINVERSE iterative code. The result of the inversion in PT axes shows that the maximum horizontal principal stress (\sigma1) of Matano Fault is 256.87 \pm 1.65 degrees, which has nearly westward direction that give a sufficient force along the fault plane and generate the left lateral strike slip fault, confirmed by the principal stress orientation vector of Matano Fault and adjacent regions from World Stress Map database. The result accuracy is well resolved through jackknife resampling method. Detailed analysis will be needed to understand the characteristics of stress field and its potential to generate a significant earthquake in the future.

Keywords: principal stress, focal mechanism, Matano Fault

Topic: Solid Earth Sciences