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Physical Sciences and Mathematics Commons™

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Geology

Central Washington University

2001

Articles 1 - 2 of 2

Full-Text Articles in Physical Sciences and Mathematics

Mantle Control Of Plate Boundary Deformation, Timothy I. Melbourne, Don Helmberger Oct 2001

Mantle Control Of Plate Boundary Deformation, Timothy I. Melbourne, Don Helmberger

Faculty Scholarship for the Cascadia Hazards Institute

The seismic wavefield propagating along the recently instrumented Pacific-North American plate boundary (California) displays remarkable variation, with regional shear waves arriving at coastal stations up to 20 seconds earlier than equidistant stations in eastern California. Broadband modeling of this data reveals that coastal paths sample fast upper mantle typical of Miocene-aged ocean plate (> 50 Km thickness). Inland paths sample slower uppermost mantle, with the seismic lithosphere, or lid, measuring less than 5 Km thick, characteristic of the Basin and Range extensional province. The boundary in the uppermost mantle between these provinces is sharp, expressing the juxtaposition of the stronger …

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Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka Feb 2001

Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) results from networks spanning the Eastern California shear zone and adjacent Sierra Nevada block, occupied annually between 1993 and 1998, constrain plate margin kinematics. We use an elastic block model to relate GPS station velocities to long‐term fault slip rate estimates. The model accounts for elastic strain accumulation on the San Andreas fault, as well as faults of the Eastern California shear zone. South of the Garlock fault, 14 mm/yr of dextral shear is distributed across the Eastern California shear zone. Some of this slip penetrates eastward into the Basin and Range, and a collective budget …

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