Publication Date:
2013-10-01
Description:
We investigate coseismic deformation of the 24 March 2011 M w 6.8 Tarlay, Myanmar, earthquake using ALOS PALSAR data from both descending and ascending passes. Using high-quality synthetic aperture radar interferograms and amplitude-offset images, the nearly linear surface rupture is well traced along the western end of the Nam Ma fault and strikes ~69°. From both descending and ascending pass Interferometric Synthetic Aperture Radar data and a rigorous maximum a posteriori probabilistic inversion method, we infer that the event involved mostly a pure left-lateral strike-slip rupture with near-vertical geometry. Our one-segment model shows that the maximum slip of ~4.1 m occurred at ~4 km depth, much larger than the slip at the surface. Both interferograms also reveal a small segment to the east of the main rupture, in a densely populated farming area. Our inversion of a two-segment model shows a similar slip distribution on the main fault, in addition to ~0.1–0.3 m left-lateral slip with normal component on a 58° north-dipping segment. The total seismic moment from the two-segment model is 1.95 x 10 19 N·m, equivalent to an M w 6.79 earthquake, which is comparable to the U.S. Geological Survey seismic inversion estimate of 2.10 x 10 19 N·m ( M w 6.84). The earthquake occurred within a group of east-northeast-striking left-lateral strike-slip faults near the Myanmar–Laos border, which are seismically active and reflect a system of actively clockwise rotating blocks. Online Material: Figures of InSAR observations, amplitude-offset maps, InSAR deformation decomposition, one segment model inversion residuals, single data set inversion results, and tectonic setting.
Print ISSN:
0037-1106
Electronic ISSN:
1943-3573
Topics:
Geosciences
,
Physics
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