HYPOCENTER RELOCATION USING TELESEISMIC DOUBLEDIFFERENCE AND 3D SEISMIC VELOCITY MODEL FOR EARTHQUAKE AROUND INDONESIA SINCE APRIL 2009 TO JANUARY 2017
Indonesian territory is one of the areas that has interesting geological conditions, this is caused by the Indonesian tectonic itself that controlled by the collision of four major plates such as Eurasia, Indo-Australia, Pacific and Philippine where interaction between the plates results in complex...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/24754 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Indonesian territory is one of the areas that has interesting geological conditions, this is caused by the Indonesian tectonic itself that controlled by the collision of four major plates such as Eurasia, Indo-Australia, Pacific and Philippine where interaction between the plates results in complex dynamics followed by the high level of seismicity. The availability of denser seismometer network because the existence of Indonesia Tsunami Early Warning System (ina-TEWS) after Aceh-Andaman megathrust earthquake with 9.1 Mw in 2004 and Nias earthquake with 8.6 Mw in 2005, had supported seismicity studies in Indonesia which one of them is hypocenter relocation.. In this study, hypocenter relocation process is done by applying the teleseismic doubledifference (TeletomoDD) relocation method which combining the arrival times of P and S waves from the station with local, regional and teleseismic distance.The earthquake catalog data are obtained from the Indonesia Agency for Meteorology, Climatology, and Geophysics (BMKG) for the period of May 2009 to January 2017. Estimating travel time calculations are using 3D seismic velocity model with grid sizes 10x10 for Indonesian region and 1D velocity model for outside Indonesia region. Relocation result showed a significant reduction in travel time residuals compared to initial earthquake data catalog, From the epicenter shifting result (horizontal shifting) showed the dominant shifting pattern occurs perpendicular to the strike of slab subduction. This case happens because BMKG hypocenter catalog is calculated by using 1D seismic velocity model that not accommodation lateral velocity anomaly that causes by subduction occurrence. Moreover, the relocation result also showed seismicity pattern that more clear to represent tectonics features. Based on seismic distribution can be concluded that the depth of Wadati-Benioff Zone (WBZ) of Sunda Trench is increasing from north to the South of Sumatra and then the subduction is steeper from west to the east of Java and Nusa Tenggara island. The relocation result of Padang Earthquake with 7.9 Mw in 2009 and other significant earthquakes with the focal mechanism of Global Centroid Moment Tensor (Global CMT)has obtained a result that confirms the existence of backthrust tectonic feature and intraslab earthquake around Mentawai region. |
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