JpGU-AGU Joint Meeting 2020

Presentation information

[J] Poster

S (Solid Earth Sciences ) » S-SS Seismology

[S-SS14] Crustal Deformation

convener:Tadafumi Ochi(Institute of Earthquake and Volcano Geology, Geological Survey of Japan, The National Institute of Advanced Industrial Science and Technology), Masayuki Kano(Graduate school of science, Tohoku University)

[SSS14-P27] Toward the development of a kinematic block motion model in Indonesia based on GNSS observation

*Rio Raharja1, Takeo Ito1, Hiroshi Kimura1, Irwan Meilano2 (1.Graduate School of Environmental Studies, Nagoya University, Japan, 2.Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Indonesia)

Indonesia is located in a tectonically complex region and lies in the interaction of four major plates. This interaction resulted in seismic activity in Indonesia and is one of the highest in the world. The earthquake not only occurred along a trench but also in inland fault, which is some of them were destructive. With this condition, research on evaluating the earthquake potential in Indonesia becomes urgent. To assess the earthquake potential, defining the boundaries between each crustal block become fundamental.

In this research, we use GNSS data derived from Indonesia CORS Network (InaCORS) and Sumatran GPS Array (SuGAR). The total number of sites that used in this research is 205 sites with a period from 2008 to 2018. We use Bernese 5.2 software for analyzing the GNSS data and get the velocity field. In order to evaluate the quality of our velocity field, we compare our velocity field with previous study (Koulali et al., 2017). We estimate the euler pole of Koulali's Sunda block. In this estimation, we only used the same sites with Koulali et al. (2017). The biggest difference between our velocity field and Koulali et al. (2017) is about 3 mm/yr. In here we assume that this difference is due to the differences in the observation period and the observation errors.

Our velocity field in the eastern part of Indonesia (from 120oE to the east) is almost completely in line with the block boundaries defined by Bird (2003). In other hand, in the western part (from 120oE to the west), our velocity filed shows disagreement with his block boundaries in Sumatra region. In order to resolve this disagreement, we define new block boundaries in the western part and also make some modification of block boundaries from previous studies in the eastern part.

We employ the MCMC (Markov Chain Monte Carlo) method to generate many kinematic block motion models and choose the optimum model based on AIC (Akaike's Information Criterion). By using the optimum model, we also estimate the relative motion between each block, the euler pole for each block, and the coupling ratio especially in Java region due to subduction of Australian plate that not be done by some previous researches. We also use seismic data in order to evaluate our block boundaries.