Title: Geodetic Sensor Web for Natural Hazards Research and Applications
Presenting Author: Jennifer S Haase
Organization: University of California, San Diego
Co-Author(s): Y. Bock, J. Geng, A. Moore, G. Offield, M. Squibb, I. Small, S. Gutman, J. Laber, E. Yu, R. Clayton, S. Kedar

Abstract:
The objective of this project is to develop and deploy SIO Geodetic Modules that transform ground based Global Positioning System (GPS) receivers into a web of sensors that provide advanced geophysical products to users for rapid response to natural hazards. The currently operating permanent GPS stations in the US are operated by many independent agencies and provide raw observations of the distance from the receiver to each GPS satellite. Advanced analysis to provide millimeter level positioning useful for monitoring earthquake ground motion is usually carried out at central processing facilities. Derived products such as atmospheric precipitable water useful for weather prediction are also calculated from GPS signal delays at a central processing facility. This project develops software and low-cost hardware to move this analysis into the SIO Geodetic Module at the measurement sites so that each site can operate as an independent node in a sensor web that can provide higher-level products directly to users. The SIO Geodetic Module also provides an interface for additional sensors at the measurements sites. We have upgraded 17 geodetic GPS stations in southern California near the San Jacinto and San Andreas faults with SIO Geodetic Modules and augmented them with accelerometer sensors. We have augmented one SIO Geodetic Module with a meteorological sensor. We have developed the infrastructure to supply remote sites with auxiliary analysis data necessary to derive final products at the sites. We are currently developing the embedded analysis software to be uploaded to the modules. By transmitting data from the new sensor hardware to our central analysis facility, we are currently providing data analysis for real-time derived position, velocity, and acceleration of ground motion using a newly developed Precise Point Positioning with Ambiguity Resolution with Accelerometers (PPP-ARA) tightly coupled Kalman-filtered analysis technique. This melds the capabilities of high precision GPS to recover fault offset and accelerometers to record strong shaking, simultaneously and at higher precision. These products are being exported from the analysis center to users at the Southern California Earthquake Center. We are currently sending low-latency real-time derived precipitable water vapor from one test SIO geodetic module equipped with a meteorological sensor and other sites with legacy meteorological sensors to the National Oceanic and Atmospheric Administration for evaluation. The precipitable water vapor data was used by the National Weather Service forecast offices in San Diego County in 2013 and 2014 for situational awareness to support flash flood watches during the monsoon season. Progress on the AIST project this fall will concentrate on embedding the analysis software within the geodetic module at the remote site, in order to reduce latency further and increase resiliency of the system for rapid natural hazard response. By demonstrating the practical utility of real-time derived products from GPS infrastructure of the UNAVCO Plate Boundary Observatory and other agencies, we provide the impetus to develop funding models for future continued operation through NASA and public-private partnerships