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The upper-truncated power law applied to earthquake cumulative frequency-magnitude distributions; evidence for a time-independent scaling parameter

S. M. Burroughs and S. F. Tebbens
The upper-truncated power law applied to earthquake cumulative frequency-magnitude distributions; evidence for a time-independent scaling parameter
Bulletin of the Seismological Society of America (December 2002) 92 (8): 2983-2993

Abstract

Earthquake cumulative frequency-magnitude (CFM) distributions are described by the Gutenberg-Richter power law where the exponent is the b-value. Although it has been reported that the b-value changes before large earthquakes, we find that an upper-truncated power law applied to earthquake CFM distributions yields a time-independent scaling parameter, herein called the b-value. We analyze earthquakes associated with subduction of the Nazca plate beneath South America and find a region of isolated seismic activity at depths greater than 500 km between 20 degrees S and 30 degrees S. For the entire record, 1973-2000, the earthquake CFM distribution in this isolated region is well described by a Gutenberg-Richter power law with b = 0.58. The data set includes several large seismic events with m (sub b) > or =6.8. A power law applied to the CFM distributions for the short time intervals are better described by an upper-truncated power law than by a power law. The b-value determined by applying an upper-truncated power law to the short time intervals is equal to the b-value obtained by applying the Gutenberg-Richter power law to the entire record. Temporal changes in b-value are due to temporal fluctuations in maximum magnitude. Analysis of four Flinn-Engdahl regions, two in subduction zones and two along spreading ridges, demonstrates wider applicability of the results. The b-value is an unchanging characteristic of the system that may be determined from a short-term record.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 92
Serial Issue: 8
Title: The upper-truncated power law applied to earthquake cumulative frequency-magnitude distributions; evidence for a time-independent scaling parameter
Affiliation: University of South Florida, College of Marine Science, St. Petersburg, FL, United States
Pages: 2983-2993
Published: 200212
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 31
Accession Number: 2003-030989
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: University of Tampa, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200310
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