HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Burroughs, S. M. Articles by Tebbens, S. F. Search for Related Content GeoRef GeoRef Citation

The Upper-Truncated Power Law Applied to Earthquake Cumulative Frequency-Magnitude Distributions: Evidence for a Time-Independent Scaling Parameter

University of South Florida
College of Marine Science
St. Petersburg, Florida 33701
sburroughs{at}ut.edu
tebbens{at}marine.usf.edu(S.M.B., S.F.T.)
University of Tampa
Department of Chemistry and Physics
Tampa, Florida 33606
(S.M.B.)

Manuscript received 2 July 2001.

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 -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° S and 30° 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_b 6.8. A power law applied to the CFM distributions for short time intervals between the large events yields b-values greater than the b-value for the entire record. CFM distributions for the short time intervals are better described by an upper-truncated power law than by a power law. The -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 -value is an unchanging characteristic of the system that may be determined from a short-term record.

This article has been cited by other articles:

				Regression Analysis with Truncated Samples and Its Application to Ground-Motion Attenuation Studies Bulletin of the Seismological Society of America, August 1, 2004; 94(4): 1369 - 1378.