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Revisiting operational aftershock forecasting in the eastern Intermountain West

Maria Mesimeri and Kristine L. Pankow
Revisiting operational aftershock forecasting in the eastern Intermountain West
Seismological Research Letters (April 2022) 93 (4): 2259-2267


We present a magnitude-dependent aftershock model for the eastern Intermountain West (IMW) that can be used to inform and improve reliability of initial U.S. Geological Survey (USGS) operational aftershock forecasts (OAFs). The model is derived after considering recent M> or =5.0 aftershock sequences in the eastern IMW, and careful identification of M<5.0 aftershock sequences from regional earthquake catalogs (western Montana, Utah). We propose a workflow for M<5.0 earthquake sequences that consists of: (1) spatiotemporal analysis of magnitude of completeness, (2) application of multiple declustering-clustering algorithms, (3) discrimination between mainshock-aftershock sequences (MS-AS) and earthquake swarms, and (4) synthesizing the results to determine the final list of MS-AS. In addition, we examined separately aftershock sequences with 5.0< or =M<6.0 and M> or =6.0 and find a notable difference in earthquake productivity. Our results show that the proposed model for IMW differs from the one used in the USGS OAF, and highlights the need for region-specific aftershock modeling. This study validates the hypothesis that earthquake sequences following large surface-faulting earthquakes in the eastern IMW, and perhaps generally in the Basin and Range Province, behave fundamentally differently than those following moderate-size earthquakes.

ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 93
Serial Issue: 4
Title: Revisiting operational aftershock forecasting in the eastern Intermountain West
Affiliation: University of Utah, University of Utah Seismograph Stations, Salt Lake City, UT, United States
Pages: 2259-2267
Published: 20220413
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 42
Accession Number: 2022-026053
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
N40°00'00" - N47°49'60", W116°00'00" - W110°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202221
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