Pre-seismic, co-seismic and post-seismic displacements associated with the Bhuj 2001 earthquake derived from recent and historic geodetic data |
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| Authors: | Sridevi Jade M Mukul I A Parvez M B Ananda P D Kumar V K Gaur R Bendick R Bilham F Blume K Wallace I A Abbasi M Asif Khan S Ulhadi |
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| Institution: | (1) CSIR Centre for Mathematical Modelling and Computer Simulation, 560 037 Bangalore, India;(2) CIRES & Department of Geol. Sci., Univ. of Colorado, 80309-0399 Boulder, CO, USA;(3) University of Peshawar, 25 120 Peshawar, Pakistan |
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| Abstract: | The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history of major earthquakes. Great
Triangulation Survey points (GTS) were first installed in the area in 1856–60 and some of these were measured using Global
Positioning System (GPS) in the months of February and July 2001. Despite uncertainties associated with repairs and possible
reconstruction of points in the past century, the re-measurements reveal pre-seismic, co-seismic and post-seismic deformation
related to Bhuj earthquake. More than 25 Μ-strain contraction north of the epicenter appears to have occurred in the past
140 years corresponding to a linear convergence rate of approximately 10 mm/yr across the Rann of Kachchh. Motion of a single
point at Jamnagar 150 km south of the epicenter in the 4 years prior to the earthquake, and GTS-GPS displacements in Kathiawar
suggests that pre-seismic strain south of the epicenter was small and differs insignificantly from that measured elsewhere
in India. Of the 20 points measured within 150 km of the epicenter, 12 were made at existing GTS points which revealed epicentral
displacements of up to 1 m, and strain changes exceeding 30 Μ-strain. Observed displacements are consistent with reverse co-seismic
slip. Re-measurements in July 2001 of one GTS point (Hathria) and eight new points established in February reveal post-seismic
deformation consistent with continued slip on the Bhuj rupture zone. |
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| Keywords: | Global Positioning System (GPS) Geodesy Great Triangulation Survey (GTS) displacements Bhuj earthquake strain baseline lengths |
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