Real-time back azimuth for earthquake early warning

Andreas S. Eisermann, Alon Ziv, Gilles H. Wust-Bloch

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


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.

Original languageEnglish
Pages (from-to)2274-2285
Number of pages12
JournalBulletin of the Seismological Society of America
Issue number4
StatePublished - 1 Aug 2015
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology


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