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Exploiting the Demographics of “Did You Feel It?” Responses to Estimate the Felt Area of Moderate Earthquakes in California

2017; Seismological Society of America; Volume: 88; Issue: 2A Linguagem: Inglês

10.1785/0220160041

1938-2057

John Boatwright, Eleyne L. Phillips,

Landslides and related hazards

Research Article| February 01, 2017 Exploiting the Demographics of "Did You Feel It?" Responses to Estimate the Felt Area of Moderate Earthquakes in California John Boatwright; John Boatwright aU.S. Geological Survey, MS 977, 345 Middlefield Road, Menlo Park, California 94025 U.S.A.boat@usgs.gov Search for other works by this author on: GSW Google Scholar Eleyne Phillips Eleyne Phillips aU.S. Geological Survey, MS 977, 345 Middlefield Road, Menlo Park, California 94025 U.S.A.boat@usgs.gov Search for other works by this author on: GSW Google Scholar Author and Article Information John Boatwright aU.S. Geological Survey, MS 977, 345 Middlefield Road, Menlo Park, California 94025 U.S.A.boat@usgs.gov Eleyne Phillips aU.S. Geological Survey, MS 977, 345 Middlefield Road, Menlo Park, California 94025 U.S.A.boat@usgs.gov Publisher: Seismological Society of America First Online: 14 Jul 2017 Online Issn: 1938-2057 Print Issn: 0895-0695 © Seismological Society of America Seismological Research Letters (2017) 88 (2A): 335–341. https://doi.org/10.1785/0220160041 Article history First Online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation John Boatwright, Eleyne Phillips; Exploiting the Demographics of "Did You Feel It?" Responses to Estimate the Felt Area of Moderate Earthquakes in California. Seismological Research Letters 2017;; 88 (2A): 335–341. doi: https://doi.org/10.1785/0220160041 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 We combine "Did You Feel It?" (DYFI) responses with the populations of reporting and nonreporting ZIP codes to improve estimates of the lowest intensities (modified Mercalli intensity; 1≤MMI≤3) and the overall felt area for moderate earthquakes. We presume that participation in the DYFI website is sufficiently widespread to interpret shaking in nonreporting ZIP codes as "not felt." For most moderate earthquakes, no nonreporting ZIP codes are located near the earthquake; reporting and nonreporting ZIP codes overlap over intermediate distances; and few reporting ZIP codes are located at regional distances. We combine the intensities from reporting and nonreporting ZIP codes by weighing the average intensity in each reporting ZIP code by the number of reports and by weighing the "not felt" intensity in each nonreporting ZIP code by the population/5000. We reduce the average intensities for underreporting ZIP codes, where the number of reports is less than the population/5000, to account for the nonreporting population. We refer to the combination of intensities from reporting, underreporting, and nonreporting ZIP codes as the revised community decimal intensity (CDI*) to distinguish it from the standard CDI of Wald et al. (1999). This revision significantly improves estimates of the lowest intensities. We contour the revised intensity distributions and interpret the CDI*=1.5 contour as the limit of the felt area. This contour is well determined in densely populated areas and adequately determined in sparsely populated areas. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.