1-DIMENSIONAL RHEOLOGICAL STRUCTURE MODEL IN CENTRAL SULAWESI FOLLOWING THE 2018 PALU-DONGGALA EARTHQUAKE BASED ON GPS DATA JUNE-NOVEMBER 2019

• Main Author: Prajadita Rahmadani, Desya
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75676
• Institution: Institut Teknologi Bandung

Indonesia is a country with complex tectonic conditions because it is in a convergent plate area. One of the major seismic activities that has occurred is the Palu-Donggala earthquake in 2018 with a magnitude of M 7,5. The movement of the Palu-Koro fault is thought to be the main source of the Palu-Donggala earthquake. The Palu-Koro fault is the main structure in Central Sulawesi in the form of a lateral shear fault with a displacement of approximately 40 mm/year. Based on studies, large earthquakes will usually be followed by post-seismic deformation, where one of the mechanisms is viscoelastic relaxation. Viscoelastic relaxation is caused by mechanisms such as viscous flows in the Earth's upper mantle and/or lower crust. This effect can be calculated and modeled, using Maxwell modeling, which is processed using VISCO1D software. The rheological model is created and the misfit between model and the observation data is calculated. The smaller the misfit value, the more suitable the modeling is with the observed data. There are 33 input models processed in the study with Maxwell viscosity range 1.1015 Pa s to 1.1020 Pa s and thickness of elastic layer in the range of 10 to 40 km. Observation data are GPS coordinate movements at 7 points, to be precise in Palu City, Donggala Regency, and Sigi Regency. For the duration of the study, from June 2019 to November 2019, the data is using 4 station points from ITB and Untad, also 3 other data are using from InaCORS BIG. The results of the study show that there is the smallest misfit value calculated using the mean absolute error, which is 0,2061 in the rheological model with a Maxwell viscosity of 8.1016 Pa s and a layer thickness of 25 km.