This Grant for Rapid Response Research (RAPID) will support installation and initial one year costs of the establishment of a mixed mode geostationary satellite (Inmarsat Broad Global Area Service - BGAN), low Earth orbiting satellite (IRIDIUM), and cellular data communications solution for Division of Earth Sciences research program, RAPID-supported, continuously operated GPS stations (CGPS) to be installed in Chile and Argentina in response to the February 27, 2010 M 8.8 Maule mega-earthquake in Chile. The communications solution will allow for daily downloads of 15 second position observations and short burst transmission of 1 Hz observations for up to 10 events from a planned 25 station continuous GPS network covering an aperture of nearly 100,000 km2 in Chile and Argentina, including stations on ocean islands on the Pacific Plate (Robinson Crusoe, Selkirk, and San Felix Islands). Twenty GPS stations will have BGAN uplinks, one will have an IRIDIUM uplink and four will rely on cellular modems and in-county cellular service providers. Given the current unreliability of Chilean cellular communications following the Maule earthquake and vibrant aftershock sequence, the proposed solution should guarantee robust real-time data return to the UNAVCO GPS Data Archive, through which all observational data will be made immediately and freely available via the web. The Maule subduction related mega-earthquake occurred at the boundary between the Nazca and South American tectonic plates with an epicenter about 230 km north of the source region of the magnitude 9.5 earthquake of May, 1960, the largest earthquake ever recorded worldwide. The Maule mega-quake moment release places it in the top five largest earthquakes ever recorded. The aftershock sequence (some 300 aftershocks have already been reported by USGS NEIC) and post-seismic crustal deformation are certain to be active and large. Fully capturing the signature of the elastic and viscoelastic deformation response of the crust and the upper mantle to this earthquake promises to yield unprecedented insights into the rheological behavior of the crust and upper mantle. Never before has an earthquake of this magnitude been observed with the planned spatial and temporal resolution and fidelity planned for this post-response GPS network. Real-time high fidelity data from this GPS network will provide important contributions to mitigating future earthquake and related tsunami and landslide hazards. Close cooperation between U.S. and Chilean geoscientists supports international scientific cooperation in the public interest. The data collected will also allow for corrections to the Chilean cadastral reference frame, which was substantially distorted by the meter-scale motions associated with this event. Real property issues will be addressed. Finally, NSF support will be leveraged by industry support as GPS manufacturer Trimble will donate at least 6 more CGPS stations to this effort as a result of the NSF-funded effort.
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Prior to the Mw8.8 Maule, Chile earthquake on 27 February, 2010, the rapid deployment of GPS stations to monitor post-seismic crustal deformation in response to earthquakes had not included data communications. The data from these stations had to be manually retrieved by field staff, requiring periodic visits to remote and often damaged areas at considerable expense, and a lack of continuous data availability limited the ability of scientists to analyze critical data and diagnose station failures in a timely fashion. This project saw the development, testing, deployment and operation of new portable, self-contained data communications systems in the epicentral region of the Maule earthquake, based on the commercially operated Inmarsat BGAN (Broadband Global Area Network) satellite system, and supplemented with cellular data service where available. The systems performed very well and proved to be robust and cost effective, allowing continuous access to station health, daily 15-sec sample rate GPS data files, and on-demand access to 1-sec files for seismological analysis following aftershocks. The data retrieved through these systems were analyzed by investigators and results published in over 12 peer-reviewed articles and conference abstracts in the past two years. The 25 data communications systems used during this 27-month project have been returned to the UNAVCO Facility and are available for use by investigators at future event-response or other temporary GPS station deployments. The technology we developed has since been used at permanent GPS stations at remote UNAVCO-operated GPS stations in Alaska, Africa, and the Caribbean and will be used by the EarthScope USArray project to retrieve seismic data from hundreds of stations to be deployed in Alaska in the coming years.
