A Statistical Method of Identifying Dependent Events and Earthquake Aftershocks

Research Article| July 01, 1974 A Statistical Method of Identifying Dependent Events and Earthquake Aftershocks Seymour Shilen; Seymour Shilen Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts Search for other works by this author on: GSW Google Scholar M.N. Toksöz M.N. Toksöz Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts Search for other works by this author on: GSW Google Scholar Author and Article Information Seymour Shilen Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts M.N. Toksöz Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts Publisher: Seismological Society of America First Online: 09 Mar 2017 Online Issn: 1938-2057 Print Issn: 0895-0695 © 1974 by the Seismological Society of America Seismological Research Letters (1974) 45 (3): 3–16. https://doi.org/10.1785/gssrl.45.3.3 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Seymour Shilen, M.N. Toksöz; A Statistical Method of Identifying Dependent Events and Earthquake Aftershocks. Seismological Research Letters 1974;; 45 (3): 3–16. doi: https://doi.org/10.1785/gssrl.45.3.3 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 A statistical method of detecting dependent events and aftershocks using spatial and temporal information was developed and applied to Japan and California earthquake catalogs. On the basis of a statistic s s=πr2ktwhere r is the distance between two events, k is the normal earthquake rate and t is the time interval between the events, a decision was made whether a pair of events were dependent. The theoretical distribution of s for a catalog consisting of only independent events was compared to the actual catalogs. On the basis of the differences between the distributions, the number of inferred dependent events was determined.This discrimination technique was applied to the earthquake catalogs of Northern Japan (1926–1960) and Southern California (1934–1960). Thirty percent of all events in the Japan catalog and 42 percent of events in the Southern California logs were identified as dependent events.The statistical properties of the catalogs without dependent events were examined, in particular with respect to the Poisson process. Some small discrepancies with the Poisson process still existed using a decision threshold of s=0.02Clusters of events were found that could not be related to any large magnitude main event. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.