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

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 2014Mw 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 24 s after the event origin time, which, after optimizations, was reduced to 14 s (≈ 8 s S wave travel time, ≈ 6 s 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.