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Physical Sciences and Mathematics Commons

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Earth Sciences

Central Washington University

Series

2009

Seismology

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

Future Cascadia Megathrust Rupture Delineated By Episodic Tremor And Slip, James S. Chapman, Timothy I. Melbourne Nov 2009

Future Cascadia Megathrust Rupture Delineated By Episodic Tremor And Slip, James S. Chapman, Timothy I. Melbourne

Faculty Scholarship for the Cascadia Hazards Institute

A suite of 15 episodic tremor and slip events imaged between 1997 and 2008 along the northern Cascadia subduction zone suggests future coseismic rupture will extend to 25 km depth, or approximately 60 km inland of the Pacific coast, rather than stopping offshore at 15 km depth. An ETS-derived coupling profile accurately predicts GPS measured interseismic deformation of the overlying North American plate, as measured by approximately 50 continuous GPS stations across western Washington State. When extrapolated over the 550-year average recurrence interval of Cascadia megathrust events, the coupling model also replicates the pattern and amplitude of coseismic coastal subsidence …


Seismic And Geodetic Constraints On Cascadia Slow Slip, Timothy I. Melbourne, Aaron G. Wech, Kenneth C. Creager Oct 2009

Seismic And Geodetic Constraints On Cascadia Slow Slip, Timothy I. Melbourne, Aaron G. Wech, Kenneth C. Creager

Faculty Scholarship for the Cascadia Hazards Institute

Automatically detected and located tremor epicenters from episodic tremor and slip (ETS) episodes in northern Cascadia provide a high-resolution map of Washington’s slow slip region. Thousands of epicenters from the past four ETS events from 2004 to 2008 provide detailed map-view constraints that correlate with geodetic estimates of the simultaneous slow slip. Each of these ETS events exhibits remarkable similarity in the timing and geographic distribution of tremor density and geodetically inferred slip. Analysis of the latest 15-month inter-ETS period also reveals ageodetic tremor activity similar both in duration and extent to ETS tremor. Epicenters from both ETS and inter- …


Fold And Thrust Partitioning In A Contracting Fold Belt: Insights From The 1931 Mach Earthquake In Baluchistan, Walter Szeliga, Roger Bilham, Daniel Schelling, Din Mohamed Kakar, Sarosh Lodi Oct 2009

Fold And Thrust Partitioning In A Contracting Fold Belt: Insights From The 1931 Mach Earthquake In Baluchistan, Walter Szeliga, Roger Bilham, Daniel Schelling, Din Mohamed Kakar, Sarosh Lodi

Faculty Scholarship for the Cascadia Hazards Institute

Surface deformation associated with the 27 August 1931 earthquake near Mach in Baluchistan is quantified from spirit-leveling data and from detailed structural sections of the region interpreted from seismic reflection data constrained by numerous well logs. Mean slip on the west dipping Dezghat/Bannh fault system amounted to 1.2 m on a 42 km x 72 km thrust plane with slip locally attaining 3.2 m up dip of an inferred locking line at approximately 9 km depth. Slip also occurred at depths below the interseismic locking line. In contrast, negligible slip occurred in the 4 km near the interseismic locking line. …