MRI: Acquisition of 15 High-rate GPS Units for Developing a Broadband Earthquake Observation System in Puerto Rico and the U.S. Virgin Islands

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Funds from this Major Research Instrumentation (MRI) Program grant will support acquisition of GPS equipment and the installation of high sample rate (1 Hz) Global Positioning System (GPS) network in Puerto Rico and the U.S. Virgin Islands. The PI's will collocate GPS sites at seismic stations operated by the Puerto Rico Seismic Network and the Puerto Rico Strong Motion Program. Installation of the network at remote field sites will be accomplished with UNAVCO engineering assistance. Data from the GPS network will record long-period (minutes) seismic waves as a possible means for detecting tsunamigenic earthquakes. Broadband seismometers are generally unable to capture the full bandwidth of long period ground motions following very large earthquakes (e.g., the Dec. 26, 2004, Mw 9.2Andaman Islands-Sumatra Earthquake) and it is therefore difficult to rapidly estimate the true magnitude of megaquakes using only seismic data. Estimation of the true magnitude (and therefore tsunami potential) of large earthquakes may be determined more accurately in a timely manner (minutes after the quake) using high rate GPS observations. Given that Puerto Rico is situated on a fault block between the North American and Caribbean tectonic plates and is surrounded and intersected by a series of active faults, seismic events are common and major earthquakes (Mw7.0) in the region have generated tsunamis in the past (e.g., 1946 Mw 8.0 Hispaniola earthquakes). The proposed GPS network will complement the existing Puerto Rico Seismic Network and the Puerto Rico Strong Motion Program, both operating within the University of Puerto Rico at Mayaguez. The high-rate GPS network will enable geoscientists to record long-period and permanent ground motion information that cannot be addressed using current seismometers in the region. The proposed integrated velocitymeter-accelerometer-GPS earthquake observation system will advance knowledge of seismic wave propagation, the kinematics and dynamics of fault rupture process, pre-seismic, co-seismic and post-seismic deformation, and is also likely to be useful for improving building and critical structure designs. The integrated GPS/seismometer network will support earthquake and tsunami hazards research and mitigation in Puerto Rico and the surrounding region. Data from GPS observations can and will also be used for real time tropospheric water vapor tomography which can be useful for weather prediction, including improved hurricane track forecasting. Raw GPS data will be freely available through the UNAVCO archive. As a result, a large number of faculty and students can potentially benefit from the data for research and applications ranging from neotectonics to atmospheric science to civil engineering. The University of Puerto Rico Mayaguez (UPRM) intend to engage a UPR student in the development of the network. UPRM is non-Ph.D.-granting, an EPSCoR (Experimental Program to Stimulate Competitive Research) and Hispanic serving institution.