Demonstration of the Cascadia G‐FAST Geodetic Earthquake Early Warning System for the Nisqually, Washington, Earthquake

Abstract

A prototype earthquake early warning (EEW) system is currently in development in the Pacific Northwest. We have taken a two-stage approach to EEW: (1) detection and initial characterization using strong-motion data with the Earthquake Alarm Systems (ElarmS) seismic early warning package and (2) the triggering of geodetic modeling modules using Global Navigation Satellite Systems data that help provide robust estimates of large-magnitude earthquakes. In this article we demonstrate the performance of the latter, the Geodetic First Approximation of Size and Time (G-FAST) geodetic early warning system, using simulated displacements for the 2001 M w 6.8 Nisqually earthquake. We test the timing and performance of the two G-FAST source characterization modules, peak ground displacement scaling, and Centroid Moment Tensor-driven finite-fault-slip modeling under ideal, latent, noisy, and incomplete data conditions. We show good agreement between source parameters computed by G-FAST with previously published and postprocessed seismic and geodetic results for all test cases and modeling modules, and we discuss the challenges with integration into the U.S. Geological Survey's ShakeAlert EEW system.

Earthquake Early Warning ShakeAlert System: Testing and Certification Platform

“…We must assess how well a particular method is able to capture these effects to improve ground-motion predictions. Additionally, although the current ShakeAlert system only includes pointsource-based alert methods, there are several methods under development that will predict additional source parameters, such as finite-fault length (e.g., Allen and Ziv, 2011;Böse et al, 2012) or slip distribution (Grapenthin et al, 2014;Minson et al, 2014;Crowell et al, 2016), as well as methods that predict ground motion directly from observed ground motion without requiring source information (e.g., Hoshiba, 2013;Hoshiba and Aoki, 2015;Kodera et al, 2016). The point-source-only assessment tools described in the Point-Source Assessment section are insufficient for determining the performance of these new methods.…”

Earthquake Early Warning ShakeAlert System: West Coast Wide Production Prototype

“…Hundreds of real-time high-precision GNSS stations are now becoming available on the West Coast (Mencin et al, 2013), and these may contribute to the ShakeAlert system's ability to characterize large events, especially by modeling the location and extent of the fault rupture (Allen and Ziv, 2011;Böse et al, 2013). Recently, scientists have developed algorithms that use real-time GNSS data to estimate magnitudes for large earthquakes (M > 6:0) and solve for the distribution of fault slip (Grapenthin et al, 2014;Minson et al, 2014;Crowell et al, 2016). Mapping the evolving rupture is important for calculating the magnitude of large events and for correctly estimating the intensity that will result across a region.…”

First result from the GEONET real-time analysis system (REGARD): the case of the 2016 Kumamoto earthquakes

“…A possible technology for real-time computation of a finite-fault estimate is established using real-time Global Navigation Satellite System (GNSS) positioning technology, which provides real-time three-dimensional ground displacements (e.g., Blewitt et al 2009;Ohta et al 2012Ohta et al , 2015Crowell et al 2012Crowell et al , 2016 Open Access *Correspondence: kawamoto-s96tf@mlit.go.jp 1 Geodetic Observation Center, Geospatial Information Authority of Japan, 1 Kitasato, Tsukuba, Japan Full list of author information is available at the end of the article Grapenthin et al 2014;Kawamoto et al 2015;. The Geospatial Information Authority of Japan (GSI) has operated a continuous real-time GNSS network, named GEONET, which consists of more than 1300 stations.…”