Estimation of Slip Distribution of the 2007 Bengkulu Earthquake from GPS Observations Using the LeastSquares Inversion Method

Authors

  • Moehammad Awaluddin Geodetic Engineering, Faculty of Engineering, University of Diponegoro, Jl. Prof. Soedharto Tembalang, Semarang, Jawa Timur 50255, Indonesia Geodesy Research Division, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha, 10 Bandung, Jawa Barat 40132, Indonesia
  • Irwan Meilano Geodesy Research Division, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha, 10 Bandung, Jawa Barat 40132, Indonesia
  • Sri Widiyantoro Global Geophysics Research Division, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung, Jawa Barat 40132, Indonesia

DOI:

https://doi.org/10.5614/itbj.eng.sci.2012.44.2.6

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 lifted up with a maximum of 0.73 m, and the vertical component at LAIS station had subsided "?0.97 m. Adding more constraints on the inversion for the Bengkulu earthquake slip distribution inferred from GPS observations can help solve the underdetermined least-squares inversion. Checkerboard tests were performed to help conduct the weighting for constraining the inversion. The inversion calculation yielded an optimal value for the slip distribution by giving the smoothing constraint a weight of 0.001 and the slip constraint a weight of = 0 at the edge of the earthquake rupture area. The maximum co-seismic slip of the optimal inversion calculation was 5.12 m at the lower area of PRKB station and BSAT station. The seismic moment calculated from the optimal slip distribution was 7.14 x 1021 Nm, which is equivalent to a magnitude of 8.5.

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