In rapid response to the Feb.27, 2010 M 8.8 Maule earthquake in Chile, investigators at multiple institutions, coordinated through the University of Hawaii will install 20 continuous GPS stations, siting stations along the rupture length by using slip distribution models to widely and most effectively instrument the active areas. Fieldwork will be lead by Mike Bevis, Ohio State University, coordinating with Sergio Barrientos at the University of Chile and the Instituto Geografico Militar de Chile. Data will be incorporated into finite-source slip inversions and publicly posted. The raw GPS data will also be made available either by manual download or in near real-time through satellite downlink.
The intellectual merit of the project are wide ranging. The PIs cite tectonic problems that may be addressed using this broad array, including understanding the coseismic displacement field of the earthquake, which will help to constrain fault rupture and tsunami models, examining the role of stress loading on the mainshock and ancillary faults, observing afterslip and spatio-temporal distribution of aftershocks, using high-rate GPS and understanding the rheological and mechanical behavior of the subduction zone and surrounding region in response to the earthquake.
The Broader Impacts include support for a large international collaboration including scientists from Chilean and French institutions, as well as support for PIs from the University of Hawaii, Ohio State, University of Memphis and Caltech. The project will produce an open archive of GPS data collected from this project as well as data acquired by the French. All data will be made openly available as soon as it is collected through UNAVCO. The data collected will be useful for a broad range of domains, including geodetic studies, structural engineering and oceanography.
This award is supported by the Tectonics and Geophysics programs in the Division of Earth Sciences (GEO/EAR) and the Office of Interational Science and Engineering, Americas Program.
On 27 February 2010 the M 8.8 Maule earthquake devastated a large portion of south-central Chile. Within 2 months of the earthquake, our team, with NSF support, had installed 33 new continuous GPS (CGPS) stations in Chile. The Maule event caused near-field peak horizontal motions in excess of 5m and static co-seismic displacements were measurable over ~ 1/3 of continental South America. These large co-seismic displacements suggested that large, transient, post-seismic displacements would also be measureable, giving us the opportunity to study both the frictional character of the co-seismic fault plane as well as the response of the South American crust and mantle. Our team has found that the zones of maximum post-seismic fault slip near Chile's Arauco peninsula corresponds both with the northern boundary of the M9.4 1960 Valdivia earthquake (the largest in recorded history) and with large subduction zone parallel positive gravity anomalies. This is consistent with the notion that the Arauco peninsula region acts as a long term (million year time-scale) rupture boundary. Additionally, we find that the data suggest the possibility that fault afterslip could be occurring as deep as 80km along the subducting Nazca plate. All of the data from the stations we have installed, many with satellite and cell phone modem connections, are publicly available in real-time or near real-time from the UNAVCO data portal.
