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 HEATON, T. H. Articles by HEATON, R. E. Search for Related Content GeoRef GeoRef Citation

Static deformations from point forces and force couples located in welded elastic Poissonian half-spaces: Implications for seismic moment tensors

U. S. GEOLOGICAL SURVEY, 525 S. WILSON AVENUE, PASADENA, CALIFORNIA 91106
EMERITUS, RUTGERS UNIVERSITY, NEW BRUNSWICK, NEW JERSEY

Abstract

We present analytic expressions for the static deformations produced by point forces and point force couples embedded in two elastic Poissonian half-spaces that are welded on a horizontal interface. We show that the deformations from point forces and from vertically dipping strike-slip point double couples vary continuously (except at the strike-slip source) as the source is moved across the welded interface. We show that the pattern of deformations from vertically dipping (or horizontally dipping) dip-slip point double couples also vary continuously as the source is moved across the welded interface, but the amplitude of the deformations jumps by the ratio of the rigidities. Finally, we show that the pattern of deformation from a point explosion source or from a point double-couple source dipping at angles other than 0° or 90° jumps as the source is moved across the boundary. We demonstrate that integration of point double-couple sources on a plane of finite extent mimics the deformation of slip on a fault plane where the total moment of the double-couples is µAD. We also demonstrate that deformations from a distribution of double couples on a horizontally dipping finite plane just above the interface are indistinguishable from the deformations produced by a similar distribution of double couples located just below the interface but with a total moment that is different by the ratio of the rigidities. This demonstrates that the moment of a dislocation that occurs between two materials is ambiguously defined. We discuss reasons why seismic moment is not a very satisfying way to parameterize the size of an earthquake. We show that potency, defined to be the integral of the slip over the rupture surface, is a more natural size scaling parameter than seismic moment.

This article has been cited by other articles:

				K. Singh and V. Kumar Displacement Field Due to a Rectangular Tension Crack in a Half-space in Welded Contact with Another Half-space Journal of Vibration and Control, March 1, 2008; 14(3): 437 - 446. [Abstract] [PDF]

				D. E. Smith, B. T. Aagaard, and T. H. Heaton Teleseismic Body Waves from Dynamically Rupturing Shallow Thrust Faults: Are They Opaque for Surface-Reflected Phases? Bulletin of the Seismological Society of America, June 1, 2005; 95(3): 800 - 817. [Abstract] [Full Text] [PDF]

				J.-P. Ampuero and F. A. Dahlen Ambiguity of the Moment Tensor Bulletin of the Seismological Society of America, April 1, 2005; 95(2): 390 - 400. [Abstract] [Full Text] [PDF]

				P. G. Richards and W.-Y. Kim Equivalent Volume Sources for Explosions at Depth: Theory and Observations Bulletin of the Seismological Society of America, April 1, 2005; 95(2): 401 - 407. [Abstract] [Full Text] [PDF]

				D. J. Wald and P. G. Somerville Variable-slip rupture model of the great 1923 Kanto, Japan, earthquake: Geodetic and body-waveform analysis Bulletin of the Seismological Society of America, February 1, 1995; 85(1): 159 - 177. [Abstract] [PDF]

				D. J. WALD, D. V. HELMBERGER, and T. H. HEATON Rupture model of the 1989 Loma Prieta earthquake from the inversion of strong-motion and broadband teleseismic data Bulletin of the Seismological Society of America, October 1, 1991; 81(5): 1540 - 1572. [Abstract] [PDF]