Optimizing Earthquake Early Warning Performance: ElarmS‐3

Research Article| January 16, 2019 Optimizing Earthquake Early Warning Performance: ElarmS‐3 Angela I. Chung; Angela I. Chung aU.C. Berkeley Seismological Laboratory, University of California, Berkeley, 307 McCone Hall #4760, Berkeley, California 94720‐4760 U.S.A., aichung@berkeley.edu Search for other works by this author on: GSW Google Scholar Ivan Henson; Ivan Henson aU.C. Berkeley Seismological Laboratory, University of California, Berkeley, 307 McCone Hall #4760, Berkeley, California 94720‐4760 U.S.A., aichung@berkeley.edu Search for other works by this author on: GSW Google Scholar Richard M. Allen Richard M. Allen aU.C. Berkeley Seismological Laboratory, University of California, Berkeley, 307 McCone Hall #4760, Berkeley, California 94720‐4760 U.S.A., aichung@berkeley.edu Search for other works by this author on: GSW Google Scholar Author and Article Information Angela I. Chung aU.C. Berkeley Seismological Laboratory, University of California, Berkeley, 307 McCone Hall #4760, Berkeley, California 94720‐4760 U.S.A., aichung@berkeley.edu Ivan Henson aU.C. Berkeley Seismological Laboratory, University of California, Berkeley, 307 McCone Hall #4760, Berkeley, California 94720‐4760 U.S.A., aichung@berkeley.edu Richard M. Allen aU.C. Berkeley Seismological Laboratory, University of California, Berkeley, 307 McCone Hall #4760, Berkeley, California 94720‐4760 U.S.A., aichung@berkeley.edu Publisher: Seismological Society of America First Online: 16 Jan 2019 Online Issn: 1938-2057 Print Issn: 0895-0695 © Seismological Society of America Seismological Research Letters (2019) 90 (2A): 727–743. https://doi.org/10.1785/0220180192 Article history First Online: 16 Jan 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Angela I. Chung, Ivan Henson, Richard M. Allen; Optimizing Earthquake Early Warning Performance: ElarmS‐3. Seismological Research Letters 2019;; 90 (2A): 727–743. doi: https://doi.org/10.1785/0220180192 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search ABSTRACT The University of California Berkeley’s (UCB) Earthquake Alert Systems (ElarmS) is a network‐based earthquake early warning (EEW) algorithm that was one of the original algorithms developed for the U.S. west‐coast‐wide ShakeAlert EEW system. Here, we describe the latest update to the algorithm, ElarmS v.3.0 (ElarmS‐3 or E3). A new teleseismic filter has been developed for E3 that analyzes the frequency content of incoming signals to better differentiate between teleseismic and local earthquakes. A series of trigger filters, including amplitude‐based checks and a horizontal‐to‐vertical ratio check, have also been added to E3 to improve the quality of triggers that are used to create events. Because of its excellent performance, E3 is now the basis for EPIC, the only ShakeAlert point‐source algorithm going forward. We can therefore also use the performance of E3 described here to assess the likely performance of ShakeAlert in the coming public rollout. We should expect false events with magnitudes between M 5 and 6 less than once per year. False events with M≥6 will be even less frequent, with none having been observed in testing. We do not expect to miss any M≥6 onshore earthquakes, though the system may miss some large offshore events and may miss one onshore earthquake between M 5 and 6 per year. Finally, in the metropolitan regions where the station density is on the order of 10 km, we expect users 20, 30, and 40 km from an earthquake epicenter to get 3, 6, and 9 s warning, respectively, before the S‐wave shaking begins. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.