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

This Article Full Text (PDF) References Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by BOLT, B. A. Articles by HERRAIZ, M. Search for Related Content GeoRef GeoRef Citation

Simplified estimation of seismic moment from seismograms

SEISMOGRAPHIC STATION UNIVERSITY OF CALIFORNIA, BERKELEY, CALIFORNIA 94720
CÁTEDRA DE GEOFÍSICA FACULTAD DE CIENCIAS FÍSICAS UNIVERSIDAD COMPLUTENSE, MADRID3, Spain

Abstract

This study proposes a method to estimate the seismic moment of regional and local earthquakes based on simple measurements made directly on Wood-Anderson seismograms. The method parallels the routine estimation of local magnitude in observatory work. The relation used is

where C is the maximum peak-to-peak amplitude read on a Wood-Anderson seismogram, D is the duration between the S arrival and the onset with amplitude C/d, is epicentral distance, and a, b, p, and d are constants. The form of the logarithmic term is suggested by the analytical expression for moment (Keilis-Borok, 1960).

Least-squares fits were made to data from 73 Wood-Anderson records of 16 central California earthquakes with seismic moments already evaluated independently from spectral analysis or broadband displacement records. The values p = 1, d, = 3 proved appropriate and subsequent regression yielded

where M_o is dyne-cm, C in millimeters, D in seconds, and in kilometers.

The corresponding moment-magnitude relation is

for 3 M_L 6.2.

The latter fit is close to an earlier empirical result (Johnson and McEvilly, 1974) for central California based on fewer cases and a different range of magnitude (2.4 M_L 5.1).

This article has been cited by other articles:

				W. J. Person Seismological notes--November-December 1993 Bulletin of the Seismological Society of America, October 1, 1994; 84(5): 1687 - 1700. [PDF]

				R. A. UHRHAMMER and B. A. BOLT The seismic magnitude of the 1989 Loma Prieta mainshock determined from strong motion records Bulletin of the Seismological Society of America, October 1, 1991; 81(5): 1511 - 1517. [Abstract] [PDF]