Uplift of the Longmen Shan and Tibetan plateau and the 2008 Wenchuan (M=7.9) earthquake
Shaw, John H.
Date of Issue2009
The Longmen Shan mountain range, site of the devastating 12 May 2008 Wenchuan (M=7.9) earthquake, defines the eastern margin of the Himalayan orogen and exhibits greater topographic relief than anywhere else in the Tibetan plateau. However, before the earthquake, geodetic and geologic surveys measured little shortening across the range front, inspiring a vigorous debate about the process by which the topography of the mountain belt is produced and maintained. Two endmember models have been proposed: (1) brittle crustal thickening, in which thrust faults with large amounts of slip that are rooted in the lithosphere cause uplift, and (2) crustal flow, in which low-viscosity material in the lower crust extrudes outward from the Tibetan plateau and inflates the crust north and east of the Himalayas. Here we use balanced geologic cross-sections to show that crustal shortening, structural relief, and topography are strongly correlated in the range front. This suggests that crustal shortening is a primary driver for uplift and topography of the Longmen Shan on the flanks of the plateau. The 2008 Wenchuan (M=7.9) earthquake, which ruptured a large thrust fault along the range front causing tens of thousands of fatalities and widespread damage, is an active manifestation of this shortening process.
DRNTU::Science::Geology::Volcanoes and earthquakes
© 2009 Macmillan Publishers Limited. This is the author created version of a work that has been peer reviewed and accepted for publication by Nature, Macmillan Publishers Limited. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at [DOI: http://dx.doi.org/10.1038/nature07837].