California Real Time Network: Test Bed for Mitigation of Geological and Atmospheric Hazards within a Modern Data Portal Environment

Global geological and atmospheric hazards such as earthquakes, volcanoes, tsunamis, landslides, storms and floods continue to wreak havoc on the lives of millions of people worldwide. High precision geodetic observations of surface displacements and atmospheric water vapor are indispensable tools in studying natural hazards along side more traditional seismic and atmospheric measurements. The rapid proliferation of dense in situ GPS networks for crustal deformation studies such as the Earthscope Plate Boundary Observatory provides us with unique data sets. However, the full information content and timeliness of these observations have not been fully developed, in particular at higher frequencies than traditional daily continuous GPS position time series. Nor have scientists taken full advantage of the complementary nature of space-based and in situ observations in forecasting, assessing and mitigating natural hazards. The primary operating mode for in situ GPS networks has been daily download of GPS data sampled at a 15-30 s sample rate, and the production of daily position time series or hourly tropospheric zenith delay estimates. However, as continuous GPS networks are being upgraded to provide even higher-frequency information approaching the sampling rates (1-50 Hz) of modern GPS receivers, and with a latency of less than 1 second, new data processing approaches are being developed. Low-latency high-rate measurements are being applied to earthquake source modeling, early warning of natural hazards (geological and atmospheric), and structural monitoring. Since 2002, more than 80 CGPS stations in southern California have been upgraded to a 1 Hz sample rate, including stations from the SCIGN and PBO networks, and several large earthquakes have been recorded. The upgraded stations comprise the California Real Time Network (CRTN - http://sopac.ucsd.edu/projects/realtime/). This prototype network provides continuous 1 Hz (upgradable to 10 Hz at some stations) GPS relative displacements and troposphere delay estimates with a latency of less than 1 s. Steps are being taken to tie these higher-order data products to the global (ITRF) reference frame, and discussions are underway to extend this capability throughout California by upgrading more UNAVCO/PBO stations. With funding from NASA, CRTN provides a test bed for developing advanced in situ- based observation systems within a modern data portal environment, which can be extended seamlessly to the entire PBO region and to other plate boundaries. I describe a prototype early warning system for earthquakes using CRTN, which is also being deployed at other plate boundaries. I show how researchers can access advanced observations of displacements and troposphere delay in real-time and replay significant events within the GPS Explorer data portal and Geophysical Resource Web Services (GRWS) environment.