Doctoral Dissertations

Author

Enyuan Jiang

Abstract

"To discern spatial and explore the possible existence of temporal variations of upper crustal anisotropy along an ~15 km section of the San Jacinto Fault Zone (SJFZ) in California, and in the Fairview, Oklahoma, region, we conduct systematic shear wave splitting (SWS) investigations using local S-wave data recorded by seismic stations. Strong spatial variations in crustal anisotropy are revealed by 1694 and 405 pairs of splitting parameters (including the fast polarization orientation and the splitting time), respectively. For both areas, for raypaths traveling through the fault zones, the fast orientations are parallel to the faults and may be attributed to fluid-filled fractures in the fault zones. For non-fault-zone crossing raypaths, the fast orientations are consistent with the orientation of the regional maximum compressive stress (SHmax) and reflect the orientation of fluid-filled cracks. For the SJFZ, a three-dimensional model of upper crustal anisotropy is constructed based on observations. An apparent increase in the raypath length normalized splitting times is observed after the 03/11/2013 magnitude 4.7 earthquake, which is attributed to changes in the spatial distribution of earthquakes before and after the M4.7 earthquake rather than reflecting temporal changes of upper crustal anisotropy. For the Fairview region, the temporal variations in the raypath normalized delay time may suggest sequences of crack opening under increased pore pressure caused by wastewater injection and crack healing. In addition, possible precursory stress relaxation was revealed using the SWS measurements before a magnitude 5.1 earthquake occurred on 2/13/2016 in the Fairview region"--Abstract, page iv.

Advisor(s)

Liu, Kelly H.
Gao, Stephen S.

Committee Member(s)

Eckert, Andreas
Maurer, Jeremy
Fu, Xiaofei

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology and Geophysics

Comments

The study was partially supported by the U.S. National Science Foundation under grants 1830644 to K. H. Liu, and S. S. Gao., and 1919789 to S. S. Gao.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2021

Journal article titles appearing in thesis/dissertation

  • Spatial variations of upper crustal anisotropy along the San Jacinto fault zone in Southern California: Constraints from shear wave splitting analysis
  • Fracture and regional stress-related upper crustal azimuthal anisotropy in the vicinity of the 2016 M5.1 Fairview, Oklahoma, earthquake

Pagination

x, 60 pages

Note about bibliography

Includes bibliographic references.

Geographic Coverage

Southern California; Central Oklahoma

Rights

© 2021 Enyuan Jiang, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11838

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