Collaborative Research: Structure and depth extent of lithospheric shear zones surrounding continental transform faults

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项目编号	1927246
	Collaborative Research: Structure and depth extent of lithospheric shear zones surrounding continental transform faults
	Vera Schulte-Pelkum (Principal Investigator)
主持机构	University of Colorado at Boulder
项目开始年	2019
	2019-10-01
项目结束日期	2022-09-30
资助机构	US-NSF
项目类别	Standard Grant
项目经费	125319(USD)
国家	美国
语种	英语
英文摘要	At continental transform faults such as the San Andreas, one tectonic plate slides horizontally relative to its neighbor. Because such faults lie on land and often in populated areas, the resulting earthquakes dramatically impact local populations. It remains debated how plates deform beneath the shallow (~10 km), top layer where earthquakes are generated. At larger depths, underlying rocks transition from brittle to ductile deformation. But whether the shear zone underneath the fault remains narrow for tens of km, or whether deformation widens right away is not clear. These different scenarios affect how faults are loaded, and have significant implications for seismic hazard assessment. Here, the team uses existing seismic records to investigate six major continental transform faults. Deformed rocks often exhibit crystal preferred orientations, fabrics, that can be detected with seismic waves. This is because rock fabrics affect the wave velocity which then depends on the propagation direction. By analyzing the anisotropy of seismic waves passing underneath the fault zones, the researchers probe the geometry and extent of rocks deformation. They also use geodynamic modeling constrained by geological observations; for given fault geometries and deformation properties, they predict seismic anisotropy features underneath the faults. By comparing observations and predictions, the team unravels the deformation behavior of continental transform faults. The project fosters an international collaboration with Australia and Switzerland. It provides support and training to a female graduate student, and outreach toward undergraduates and K12 students - notably from group underrepresented in Sciences - and the public. The team uses data from existing deployments crossing six continental transform faults (San Andreas, North Anatolian, Denali, New Zealand Alpine, Altyn Tagh/Kunlun, and Dead Sea). It conducts full-waveform 2-D and 3-D modeling of teleseismic shear wave splitting, as well as anisotropic receiver function analysis. The goal is to image the shear zone and broader deformation field surrounding each transform fault. The selected faults represent transforms of different ages and maturity. Existing splitting observations show systematic contrasts between faults. Combining high-resolution shear zone imaging and geodynamic modeling, the researchers investigate the degree of strain localization in the lithosphere and the shear zone geometry. They also study the possible roles of mechanical anisotropy and inherited fabrics. This project is a critical step toward establishing a model for continental lithospheric transforms and better assessing the corresponding earthquake hazards. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/214043
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Vera Schulte-Pelkum .Collaborative Research: Structure and depth extent of lithospheric shear zones surrounding continental transform faults.2019.