A Fast Earthquake Early Warning Algorithm Based on the First 3 s of the P‐Wave Coda

Abstract

Research Article| July 10, 2018 A Fast Earthquake Early Warning Algorithm Based on the First 3 s of the P‐Wave Coda Armando Cuéllar; Armando Cuéllar aCentro de Instrumentación y Registro Sísmico (CIRES), Anaxágoras 814, Colonia Narvarte, Mexico City 03020, Mexico Search for other works by this author on: GSW Google Scholar Gerardo Suárez; Gerardo Suárez bInstituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico, gerardo@geofisica.unam.mx Search for other works by this author on: GSW Google Scholar J. M. Espinosa‐Aranda J. M. Espinosa‐Aranda aCentro de Instrumentación y Registro Sísmico (CIRES), Anaxágoras 814, Colonia Narvarte, Mexico City 03020, Mexico Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2018) 108 (4): 2068–2079. https://doi.org/10.1785/0120180079 Article history first online: 10 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Armando Cuéllar, Gerardo Suárez, J. M. Espinosa‐Aranda; A Fast Earthquake Early Warning Algorithm Based on the First 3 s of the P‐Wave Coda. Bulletin of the Seismological Society of America 2018;; 108 (4): 2068–2079. doi: https://doi.org/10.1785/0120180079 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 SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract A new seismic early warning algorithm is presented that estimates a magnitude threshold using the first 3 s of the P‐wave coda on the vertical component. The algorithm considerably reduces the processing time compared to previous algorithms used by the Mexican seismic early warning system (Seismic Alert System of Mexico [SASMEX]). It was designed to alert earthquakes within the subducted Cocos plate. The tP+3 algorithm was based on a training dataset of 76 accelerograms of 25 Mexican in‐slab earthquakes, with focal depths >40 km⁠. The algorithm uses two parameters based on the unfiltered vertical component of the P waves: the sum of the cumulative quadratic acceleration, av(T) and θP a parameter that represents the slope of the cumulative acceleration. The model is based on a learning machine that linearizes piecewise the empirical relation between these two parameters and magnitude Mw⁠. The resulting algorithm was tested on nine earthquakes that took place from 2014 to 2017, recorded in 37 strong‐motion records. In addition, the algorithm was evaluated in the context of the Mexican earthquake early warning, applying it to 24 in‐slab earthquakes occurring from 1995 to 2017 (⁠5.0<Mw<7.1⁠). The magnitude of 19 earthquakes was properly estimated; for four of them, it was overestimated and in one case the magnitude was underestimated. Three earthquakes Mw>6.5 that affected Mexico City were included in the dataset: the Mw 6.5 event on 11 December 2011 and the destructive in‐slab Tehuacán and Morelos earthquakes on 15 June 1999 (⁠Mw 7.0) and 19 September 2017 (⁠Mw 7.1). The retrospective application of the tP+3 algorithm shows that these three earthquakes are correctly identified as Mw>6 and would activate a seismic alert. The tP+3 algorithm would have given an advance warning of 34, 35, and 16 s respectively, before the arrival of strong motion in Mexico City. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.