SGER: The February 28, 2001 Nisqually Earthquake: Juan de Fuca Slab Break-up, Viscoelastic Response, and Interplay with Crustal Faulting

Central Washington University, Ellensburg WA

Investigators

Abstract

Abstract Meghan Miller EAR-0119491 The PANGA consortium will install 8 continuously operating GPS stations in Puget Sound in a rapid response deployment to the Nisqually earthquake. This enhancement of PANGA is aimed at gathering basic data to answer opportune scientific questions. It also provides a demonstration of the ability of the Plate Boundary Observatory community to master the technical challenges of a post-earthquake response in a collaborative manner. The continuous GPS observations will further our understanding of these scientific issues: 1. Is the series of slab deformation events recorded in 1939,1946 and 1949 a typical sequence, and will we observe a similar sequence in the 1999 Grays Harbor, 2001 Nisqually, and some near term future event(s)? 2. How is deformation propagated from a down going slab through a viscoelastic lower lithosphere, to surface deformation? What are the rheologies that govern this complex scenario and how is deformation propagated or dissipated? 3. How do these processes reveal the budget of seismic vs. aseismic slip? 4. Is there a causal relationship between intra-slab earthquakes and deformation in the brittle upper crust? 5. How does the concentration of deformation across the Puget Lowlands, where fore-arc migration ends in a zone of concentrated strain, relate to arching of the down-going slab and its consequent deformation? 6. Is there an observable role between deeper, slab events with their broad deformation field, and teconomagmatic deformation? Page A 011 9491