Award Abstract #0216626
Leveraged acquisition of a Seattle fault GPS network: Four dimensional constraint on seismic and aseismic strain accumlation and release in the urbanized Puget Lowlands

NSF Org:	EAR Division of Earth Sciences
Initial Amendment Date:	July 29, 2002
Latest Amendment Date:	July 29, 2002
Award Number:	0216626
Award Instrument:	Standard Grant
Program Manager:	Russell C. Kelz EAR Division of Earth Sciences GEO Directorate for Geosciences
Start Date:	August 1, 2002
Expires:	July 31, 2006 (Estimated)
Awarded Amount to Date:	$225000
Investigator(s):	M. Meghan Miller meghan@cwu.edu (Principal Investigator)
Sponsor:	Central Washington University 400 E. University Way Ellensburg, WA 98926 509/963-2111
NSF Program(s):	MAJOR RESEARCH INSTRUMENTATION
Field Application(s):	0000099 Other Applications NEC
Program Reference Code(s):	OTHR, 1189, 0000
Program Element Code(s):	1189

ABSTRACT

0216626

Miller

Continuous observations using Global Positioning System (GPS) geodesy yield high-precision determination of horizontal and vertical deformation rates and their variation in time and space. This project builds on the stunning advances that data from the regional Pacific Northwest Geodetic Array (PANGA) has yielded over the last year. In partnership with the surveying community in Puget Sound, PANGA scientists will install a continuous GPS network that is optimally designed to determine the kinematics and locking of the Seattle fault zone, a major fault within the North America plate. In addition, this network provides important new constraints on the periodic recurrence of slow or silent earthquakes, which have been recently discovered along the transition zone of the Cascadia plate interface. Both studies have fundamental importance to characterizing the geodynamics of plate interaction, they also have broader impacts on quantifying seismic strain energy accumulation on a crustal fault that lies in the heart of the urbanized Puget Lowlands. This network will add new constraints to the relative balance between seismic and aseismic strain release mechanisms on the plate boundary fault that is known to generate great earthquakes (approximately magnitude 9) at frequencies of about 500 years. Finally, this project will foster the nascent collaboration between regional professional and academic communities.

The Puget Sound surveying community has formed a consortium to support coordination of new GPS technology to the urbanized Puget Lowlands. This collaboration of cities, counties, state agencies, and engineering firms is committed to installing a "virtual reference system" GPS network known as the Puget Reference System Utility (PRSU) that can provide cm-level positioning in real time. Fortuitously, this network is optimal for the earthquake and geodynamics studies outlined above, with the caveat that the solid earth deformation community has the highest standards for monumentation in order that GPS antennas track real earth motion rather than the effects of soil, gourndwater or man-made structures. The Puget Lowlands present the greatest first-order challenges to stable monument design: thick soil horizons, deep sedimentary basins in the foot wall of the Seattle fault and a mantle of debris left behind in the last glacial retreat require use of the deeply anchored drilled braced monument. Such monumentation is thus critical to making geophysically meaningful observations of great precision required by the problems posed here. This project funds geodetic quality monuments in order to leverage the PRSU GPS network for solid earth deformation studies in a highly leveraged fashion.

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PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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A. M. Miner, M. M. Miller, and V. M., Santillan.  "Progress towards a multiple-use GPS array in the Puget Sound region,"  Eos, Transactions, American Geophysical Union,  v.85,  2004, 

M. E. Caron, M. M. Miller, and D. J. Johnson.  "Neotectonic crustal deformation and seismic hazard in the Puget Sound area of the Casdacia fore-arc, Washington State,"  Eos, Transactions, American Geophysical Union,  v.83,  2002, 


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