HR: 0800h
AN: S41A-07    [Abstracts]
TI: Analyzing the Resolvability of Crustal and Mantle Velocity Anomalies beneath Tibet
AU: * Chen, C
EM: ChingwenChen2007@gmail.com
AF: University of Houston, 4800 Calhoun Rd., Houston, TX 77004, United States
AU: Zhou, H
EM: Hua-Wei.Zhou@mail.uh.edu
AF: University of Houston, 4800 Calhoun Rd., Houston, TX 77004, United States
AB: The Tibetan Plateau is a product of the largest active continent-continent collision event on Earth. A variety of models have been proposed that explain its Cenozoic tectonic evolution [Harrison et al., 1992], such as continental underthrusting, delayed underthrusting, distributed shortening, mantle lithosphere detachment and so on. Each of the models makes specific predictions about the lithosphere structure in the India-Asia collision zone that may be verifiable by seismic imaging. For instance, a recent study [Zhou and Murphy, 2005] using re- processed ISC traveltimes provided evidence for wholesale underthrusting of Indian slab beneath much of the Tibetan plateau. However, due to the lack of seismologic stations over the Tibetan region, it is necessary to quantify the resolvability of the tomographic methods and data before drawing conclusions on the velocity anomalies. As an example, the demean process (removal of the layer velocity averages or removing traveltime means) that is used in most tomography studies will hinder the ability to resolve sub-horizontal features such as the possible underthrusting Indian slab anomaly. We attempt to quantify the resolvability of the crustal and mantle velocity anomalies by conducting tomographic resolution tests along a series of 2D dip lines across the Tibetan plateau, using the actual station and event positions of the ISC dataset. For each dip line we will make several velocity models based on the lithosphere structure predicted by the tectonic models. In each resolution test, an interpreted tectonic model will be translated into a synthetic true model, traveltimes generated from the synthetic model between real event and station positions will be used to quantify the resolution of major tectonic features. The above process may allow us identifying some dip lines with the best resolvability, which will guide our further studies to better evaluate the likelihood of different tectonic models of the Tibetan region.
DE: 6982 Tomography and imaging (7270, 8180)
DE: 7203 Body waves
DE: 7270 Tomography (6982, 8180)
DE: 8180 Tomography (6982, 7270)
SC: Seismology [S]
MN: 2007 Joint Assembly