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GEAR1; a global earthquake activity rate model constructed from geodetic strain rates and smoothed seismicity

P. Bird, D. D. Jackson, Y. Y. Kagan, C. Kreemer and R. S. Stein
GEAR1; a global earthquake activity rate model constructed from geodetic strain rates and smoothed seismicity
Bulletin of the Seismological Society of America (September 2015) 105 (5): 2538-2554


Global earthquake activity rate model 1 (GEAR1) estimates the rate of shallow earthquakes with magnitudes 6-9 everywhere on Earth. It was designed to be reproducible and testable. Our preferred hybrid forecast is a log-linear blend of two parent forecasts based on the Global Centroid Moment Tensor (CMT) catalog (smoothing 4602 m> or =5.767 shallow earthquakes, 1977-2004) and the Global Strain Rate Map version 2.1 (smoothing 22,415 Global Positioning System velocities), optimized to best forecast the 2005-2012 Global CMT catalog. Strain rate is a proxy for fault stress accumulation, and earthquakes indicate stress release, so a multiplicative blend is desirable, capturing the strengths of both approaches. This preferred hybrid forecast outperforms its seismicity and strain-rate parents; the chance that this improvement stems from random seismicity fluctuations is less than 1%. The preferred hybrid is also tested against the independent parts of the International Seismological Centre-Global Earthquake Model catalog (m> or =6.8 during 1918-1976) with similar success. GEAR1 is an update of this preferred hybrid. Comparing GEAR1 to the Uniform California Earthquake Rupture Forecast Version 3 (UCERF3), net earthquake rates agree within 4% at m> or =5.8 and at m> or =7.0. The spatial distribution of UCERF3 epicentroids most resembles GEAR1 after UCERF3 is smoothed with a 30 km kernel. Because UCERF3 has been constructed to derive useful information from fault geometry, slip rates, paleoseismic data, and enhanced seismic catalogs (not used in our model), this is encouraging. To build parametric catastrophe bonds from GEAR1, one could calculate the magnitude for which there is a 1% (or any) annual probability of occurrence in local regions.

ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 105
Serial Issue: 5
Title: GEAR1; a global earthquake activity rate model constructed from geodetic strain rates and smoothed seismicity
Affiliation: University of California, Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, United States
Pages: 2538-2554
Published: 20150901
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 40
Accession Number: 2015-094174
Categories: SeismologyEnvironmental geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, geol. sketch maps
Secondary Affiliation: University of Nevada, Reno, USA, United StatesU. S. Geological Survey, USA, United States
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: 201540
Program Name: USGSOPNon-USGS publications with USGS authors
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