Seismic study of the crust and upper mantle structure in eastern Asia using ambient noise correlation and earthquake data
type: CreativeWork
description: Seismic methods using natural earthquakes are commonly applied to investigate the velocity structures of the crust and upper mantle. Among all these methods, seismic tomography is one of the most powerful tools to image the earth’s structure. Recent theoretical and experimental studies suggest that the media impulse response (Green’s function) of surface wave between two seismic stations can be retrieved from the cross correlation of diffusive wave field. This method provides additional data coverage to the study region and has been quickly used in various seismic studies. In this dissertation, I develop several tomography methods using traditional earthquake data as well as surface wave data from ambient noise correlation and apply them in eastern Asia. A joint inversion scheme using first and secondary Pg arrivals and Pn arrivals is developed to determine the crustal and uppermost mantle P wave velocity and the depth of Moho discontinuity. This method addresses the trade-off issue between the media velocity and a discontinuity location. I apply this method to the eastern and southern margin of Tibetan Plateau, where the Moho depth changes rapidly. Significant features are revealed from tomography results, in consistence of regional geological settings, including slow upper crust but fast lower crust under Sichuan Basin, rapid Moho variation, and slow Pn in the plateau and fast Pn in the borderland separated by major boundaries and faults. The mid-lower crust in the plateau is relatively slow compared to the average model and Sichuan Basin and Poisson’s ratio is anomalous (exceeding 0.3), which is consistent with weak mid-lower crust in the plateau. The crust and upper mantle shear wave velocity in China and its surrounding region is obtained from regional surface wave tomography. By combining traditional earthquake surface wave data with ambient noise correlation data, I am able to extend the Rayleigh wave group velocity period from 8 s to 120 s. Together with Ray…
abstract: Seismic methods using natural earthquakes are commonly applied to investigate the velocity structures of the crust and upper mantle. Among all these methods, seismic tomography is one of the most powerful tools to image the earth’s structure. Recent theoretical and experimental studies suggest that the media impulse response (Green’s function) of surface wave between two seismic stations can be retrieved from the cross correlation of diffusive wave field. This method provides additional data coverage to the study region and has been quickly used in various seismic studies. In this dissertation, I develop several tomography methods using traditional earthquake data as well as surface wave data from ambient noise correlation and apply them in eastern Asia. A joint inversion scheme using first and secondary Pg arrivals and Pn arrivals is developed to determine the crustal and uppermost mantle P wave velocity and the depth of Moho discontinuity. This method addresses the trade-off issue between the media velocity and a discontinuity location. I apply this method to the eastern and southern margin of Tibetan Plateau, where the Moho depth changes rapidly. Significant features are revealed from tomography results, in consistence of regional geological settings, including slow upper crust but fast lower crust under Sichuan Basin, rapid Moho variation, and slow Pn in the plateau and fast Pn in the borderland separated by major boundaries and faults. The mid-lower crust in the plateau is relatively slow compared to the average model and Sichuan Basin and Poisson’s ratio is anomalous (exceeding 0.3), which is consistent with weak mid-lower crust in the plateau. The crust and upper mantle shear wave velocity in China and its surrounding region is obtained from regional surface wave tomography. By combining traditional earthquake surface wave data with ambient noise correlation data, I am able to extend the Rayleigh wave group velocity period from 8 s to 120 s. Together with Ray…
author: Xu, Zhen
language: en
keywords: Seismic tomography, Joint inversion, Surface wave, Ambient noise correlation, Temporal changes, Tibetan Plateau
date published: 2011-08-25T22:15:32Z
date modified: 2026-07-22T22:25:26Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/26133