Real‐Time Back Azimuth for Earthquake Early Warning

Abstract

The incentive to speed up real-time location has motivated previous researchers to go beyond standard location procedures and use not only P-wave arrival at some network stations but also its nonarrival at others. In addition to being sensitive to velocity model and picking uncertainties, this approach is also highly dependent on time delays due to unknowns network latencies, processing, and packet size. Thus, seeking ways to add independent real-time constraints on earthquake location are important for earthquake early warning applications. In this study, we assess the robustness of three independent real-time back-azimuth (BAZ) determination schemes, using offline records of southern California earthquakes. We find that BAZ values computed by the three methods provide equivalent levels of accuracy. By sending the three BAZ estimates to a screening module that checks for coherency and signal-to-noise ratio criteria, we show that accurate BAZ estimates are obtainable in real time, with a standard deviation of 13°. Through examination of two earthquake scenarios that use offline data, we show that the inclusion of BAZ estimates into real-time location schemes improves the performance of real-time hypocenter determination, by cutting the time it takes to obtain well-constrained hypocenters.

Fast estimation of earthquake arrival azimuth using a single seismological station and machine learning techniques

“…The accuracy reported in this research is lower compared with results reported by Lockman &Allen, 2005 andEisermann et al, 2015; however it must to be consider that these authors works with data from several seismological station and not with a single station as this research does. Nevertheless, the result of 45.4 degrees in earthquake arrival azimuth estimation showed in this research is an improvement on that of Noda et al, 2012, who had standard deviation between 49.0 and 67.9 degrees working also with a single station.…”

Optimizing Event Detection and Location in Low‐Seismicity Zones: Case Study from Western Switzerland

“…The nanoseismic monitoring interactive location scheme HypoLine (Joswig, 2008) is then validated with NonLinLoc (NLL; Lomax et al, 2000Lomax et al, , 2009, a standard location algorithm based on residuals. Results show that the analyst-guided location scheme of nanoseismic monitoring is more robust than NLL when investigating microseismic datasets with few low-SNR phase onsets, because displaying all constraints in real time allows for superior ambiguity resolution (Eisermann et al, 2015).…”

Preparing for InSight: Evaluation of the Blind Test for Martian Seismicity

“…In the following, we focus on the six teams that provided the most complete results in terms of the number of events Detection: STA/LTA triggering and manual review Location: three probabilistic polarization analysis methods for azimuth (Selby, 2001;Eisermann et al, 2015); probabilistic body wave and Rayleigh-group travel times for distance (Panning et al, 2015;Böse et al, 2016…”