The 2014 Mw 6.0 Napa earthquake, California: Observations from real-time GPS-enhanced earthquake early warning

Abstract

Recently, progress has been made to demonstrate feasibility and benefits of including real-time GPS (rtGPS) in earthquake early warning and rapid response systems. Most concepts, however, have yet to be integrated into operational environments. The Berkeley Seismological Laboratory runs an rtGPS-based finite fault inversion scheme in real time. This system (G-larmS) detected the 2014 Mw 6.0 South Napa earthquake in California. We review G-larmS' performance during this event and 13 aftershocks and present rtGPS observations and real-time modeling results for the main shock. The first distributed slip model and magnitude estimates were available 24s after the event origin time, which, after optimizations, was reduced to 14s (≈8s S wave travel time, ≈6s data latency). G-larmS' solutions for the aftershocks (that had no measurable surface displacements) demonstrate that, in combination with the seismic early warning magnitude, Mw 6.0 is our current resolution limit. Key PointsGPS-based distributed fault slip model derived in real time for early warningReasonable first order approximation of South Napa slip distribution at Mw 5.9Mw 6.0 is resolution limit for current North California rtGPS network and processing