Title: Real-Time In-Situ Measurements for Earthquake Early Warning and Space-Borne Deformation Measurement Mission Support
Author: Yehuda Bock
Organization: Scripps Institution of Oceanography
Co-Authors: Sharon Kedar, Robert Clayton, Frank Webb, Angelyn Moore, Ellen Yu, Melinda Squibb, Brendan Crowell
The primary goal of our AIST project is to provide the most accurate and timely early warning information on global geological hazards to first responders, scientists, mission planners and policy makers. The primary mission of focus is NASAís Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI) mission. Specifically our objectives are as follows: (a) Develop a publicly available real-time ground deformation data system fusing two in situ network data sources: low latency (1 s) high-rate (1 Hz or greater) CGPS & traditional ultra-high-rate (100 Hz) seismic data (accelerometers); (b) Enable rapid access to absolute displacement waveforms, replay capability, and modeling of significant events related to global geological hazards; (c) Enable detection and preliminary modeling of signals of interest by the dense ground networks, which will help mission planners exploit less-frequent but higher resolution InSAR observations; (d) Use GPS data products to calibrate InSAR measurements for atmospheric and orbital errors, significantly increasing the accuracy of interferograms.
We review the status of our project in five areas: (1) Expansion of the California Real Time Network (CRTN), which now includes 175 GPS stations, with the newest stations in the Central Valley, San Francisco Bay Area and Cascadia region; (2) Production and streaming of displacement waveforms based on a combination of 1 Hz GPS displacements with 100 Hz accelerometer data. We demonstrate this using data from the Mw 7.2 April 4, 2010 El Mayor-Cucapah earthquake in northern Baja California, for 12 collocated GPS and accelerometer stations (less than 1.5 km apart) in southern California; (3) Fine tuning of multi-rate Kalman filter that estimates the displacement waveforms, including assigning the proper measurement variance and the system dynamics variance; (4) Continued development of the system to produce tropospheric correction maps based on GPS tropospheric delays combined with weather model data. We demonstrate this using a set of 15 short-interval, repeat-pass Envisat interferograms over southern California to assess the correction maps' ability to reduce tropospheric effects; (5) Implementation of transient detection algorithms for data quality control and rapid detection of deformation anomalies.
Access to data and resources are provided through an interactive GPS Explorer data portal environment being developed as part of an ongoing MEaSUREs project and NASA's contribution to the EarthScope project. GPS Explorer, originally designed for web-based dissemination of long-term Solid Earth Science Data Records (ESDRís) such as deformation time series, tectonic velocity vectors, and strain maps, provides the framework for seamless inclusion of the real-time data products.