Jurnal

Subsurface Structure Identification of Active Fault Based On Magnetic Anomaly Data (Case Study : Toru Fault In Sumatera Fault System)

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Abstract. Toru segment, which is one of the active faults and located in the North of Sumatra, broke in 1984 ago on Pahae Jahe’s earthquake with a magnitude 6.4 at the northern part of the fault which has a length of 23 km, and also broke again at the same place in 2008. The event of recurrence is very fast, which only 25 years old have repeatedly returned. However, in the elastic rebound theory, it probably happen with a fracture 50 cm and an average of the shear velocity 20 mm/year. The average focus of the earthquake sourced at a depth of 10 km and 23 km along its fracture zones, which can generate enough shaking 7 MMI and could breaking down buildings and create landslides on the cliff. Due to its seismic activity, this study was made to identify the effectiveness of this fault with geophysical methods. Geophysical methods such as gravity, geomagnetic and seismology are powerful tools for detecting subsurface structures of local, regional as well as of global scales. This study used to geophysical methods to discuss about total intensity of the geomagnetic anomaly data, resulted in the distribution of susceptibility values corresponding to the fault movement. The geomagnetic anomalies data was obtained from Geomag , such as total intensity measured by satellite. Data acquisition have been corrected for diurnal variations and reduced by IGRF. The study of earthquake records can be used for differentiating the active and non active fault elements. Modeling has been done using several methods, such as pseudo-gravity, reduce to pole, and upward or downward continuation, which is used to filter the geomagnetic anomaly data because the data has not fully representative of the fault structure. The results indicate that rock layers of 0 – 100 km depth encountered the process of intrusion and are dominated by sedimentary rocks that are paramagnetic, and that the ones of 100 - 150 km depth experienced the activity of subducting slab consisting of basalt and granite which are ferromagnetic and semi-ferromagnetic. This concluded that all the occurences correspond to the high seismicity and seismotectonic condition of Toru fault.

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JURPDFG16004.1

551.22 SIM s

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No. Panggil

551.22 SIM s

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Deskripsi Fisik

7 hal;ilusi;30 cm

Bahasa

English

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Klasifikasi

551.22 SIM s

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

Magnetic

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Pernyataan Tanggungjawab

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