M. B. Squibb

Modeling and On-the-Fly Solutions for Solid Earth Sciences: Web Services and Data Portal for Earthquake Early Warning System

We report on a unified on-the-fly, Web services-based observation/analysis/modeling environment for crustal deformation and natural hazards research, intended as a plug-in service for early warning systems, transfer of rapid information to civilian decision makers and the media, and educational purposes. We demonstrate an early warning system for a large earthquake in southern California using the components developed under several NASA-funded projects, including real-time GPS network infrastructure, Geophysical Resources Web Services, and GPS Explorer data portal with its on-the-fly earthquake modeling software. We generate an on-the-fly earthquake fault model based on simulated real-time (dynamic and coseismic) displacements computed by the GPS network, and viewable through GPS Explorer. Our objective is to demonstrate an operational service that could be transitioned to appropriate civilian agencies in southern California.

Twenty-Two Years of Combined GPS Products for Geophysical Applications and a Decade of Seismogeodesy

Continuous GPS monitoring on global and regional scales has become an essential component of geophysical and meteorological infrastructure for studying fundamental Earth processes that drive natural hazards, weather, and climate. The NASA-funded “Solid Earth Science ESDR System (SESES)” project provides long-term Earth Science Data Records (ESDRs), the result of a combined solution of independent GPS analyses by the Jet Propulsion Laboratory and Scripps Institution of Oceanography using a common source of metadata archived at the Scripps Orbit and Permanent Array Center. The project has now produced up to twenty-two years of consistent, calibrated and validated ESDR products for over 3,200 GPS stations in western North America, other plate boundaries, and global networks. We describe the methodology to estimate a single set of time series with 24-h resolution of station displacements in north, east and vertical components. This is followed by a time series analysis for velocities, coseismic offsets, postseismic deformation, seasonal signals and nuisance offsets, primarily due to GPS antenna changes. Realistic one-sigma velocity are on the order of 0.03–0.05 mm/year in horizontal components and 0.1–0.3 mm/year in the vertical based on time series of 10–20 year duration. We present examples of time series that are well modeled by this parameterization and of time series that exhibit residual transient motions exhibiting episodic tremor and slip (ETS) processes. The project also catalogs seismic displacement and velocity waveforms estimated for a set of historical earthquakes in Japan and the U.S. through a seismogeodetic combination of GPS and collocated strong-motion accelerometers.