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Estimation of Slip Distribution of the 2007 Bengkulu Earthquake from GPS Observation Using Least Squares Inversion Method
Moehammad Awaluddin1,2, Irwan Meilano2 & Sri Widiyantoro3
1Geodetic Engineering, Faculty of Engineering, University of Diponegoro,
Jl. Prof. Soedharto Tembalang, Semarang 50255, Indonesia
2Geodesy Research Division, Faculty of Earth Science and Technology,
Institut Teknologi Bandung, Jl. Ganesha, 10 Bandung 40132, Indonesia
3Global Geophysics Research Division, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia
Email: awal210874@yahoo.com
Abstract. Continuous Global Positioning System (GPS) observations showed significant crustal displacements as a result of the Bengkulu earthquake occurring on September 12, 2007. A maximum horizontal displacement of 2.11 m was observed at PRKB station, while the vertical component at BSAT station was uplifted with a maximum of 0.73 m, and the vertical component at LAIS station was subsided by -0.97 m. The method of adding more constraint on the inversion for the Bengkulu earthquake slip distribution from GPS observations can help solve a least squares inversion with an under-determined condition. Checkerboard tests were performed to help conduct the weighting for constraining the inversion. The inversion calculation of the Bengkulu earthquake slip distribution yielded in an optimum value of slip distribution by giving a weight of smoothing constraint of 0.001 and a weight of slip value constraint = 0 at the edge of the earthquake rupture area. A maximum coseismic slip of the optimal inversion calculation was 5.12 m at the lower area of PRKB and BSAT stations. The seismic moment calculated from the optimal slip distribution was 7.14 x 1021 Nm, which is equivalent to a magnitude of 8.5.
Keywords: Bengkulu earthquake; GPS data; least squares inversion; slip distribution.
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