Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted 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 MENDEZ, A. J. Articles by ANDERSON, J. G. Search for Related Content GeoRef GeoRef Citation

The temporal and spatial evolution of the 19 September 1985 Michoacán earthquake as inferred from near-source ground-motion records

SEISMOLOGICAL LABORATORY MACKAY SCHOOL OF MINES UNIVERSITY OF NEVADA, RENO, NEVADA 89557

Abstract

A frequency domain inversion technique is employed to image the rupture process of the 19 September 1985 Michoacán, Mexico, earthquake. A linear system is derived from the elastodynamic representation theorem and is solved for the spatial slip-velocity distribution, in the frequency bandwidth 0.0 to 0.32 Hz. The temporal behavior of slip velocity on the fault plane is then recovered by Fourier synthesis. Model complexity is penalized by seeking a solution that propagates with the most nearly constant rupture velocity and that produces the most nearly constant spatial slip distribution. At 0 Hz, the inversion of surface static displacements, as inferred from strong-motion recordings of the Guerrero accelerograph array, gives an estimate of the static offset on the fault plane. Coastal uplift data inferred from the mortality of intertidal organisms (Bodin and Klinger, 1986) is also used to further constrain the spatial slip distribution. A low-frequency image of the rupture process of the earthquake has been obtained using full-space Green's functions. Two areas of large slip amplitude are discernible, one located downdip of the reported hypocenter and the other updip of the projection on the fault plane of station La Unión. Their separation is approximately 100 km. Assuming that full-space Green's functions underestimate static offset values at the surface of a half-space by a factor of 0.5, the inferred seismic moment is 10.6 x 10²⁷ dyne-cm, 90 per cent of which is released in these two areas sustaining the largest slip. The total inferred rupture duration is approximately 56 sec. From the hypocenter, the rupture front proceeds with an average velocity estimated at 2.8 km/sec. There are indications of bilateral propagation both from the hypocentral area and from an area surrounding the projection on the fault plane of the strong-motion station La Unión. An upper bound on rupture duration at the two principal subevents is 8 sec.

This article has been cited by other articles:

				M. A. Ellis and A. L. Densmore First-order topography over blind thrusts Geological Society of America Special Papers, January 1, 2006; 398(0): 251 - 266. [Abstract] [Full Text] [PDF]

				Ground-Motion Attenuation Relationships for Cascadia Subduction Zone Megathrust Earthquakes Based on a Stochastic Finite-Fault Model Bulletin of the Seismological Society of America, June 1, 2002; 92(5): 1923 - 1932.

				T. Mikumo, T. Miyatake, and M. A. Santoyo Dynamic rupture of asperities and stress change during a sequence of large interplate earthquakes in the Mexican subduction zone Bulletin of the Seismological Society of America, June 1, 1998; 88(3): 686 - 702. [Abstract] [PDF]

				S. Horton A fault model with variable slip duration for the 1989 Loma Prieta, California, earthquake determined from strong-ground-motion data Bulletin of the Seismological Society of America, February 1, 1996; 86(1A): 122 - 132. [Abstract] [PDF]

				S. E. Hough Southern surface rupture associated with the M 7.3 1992 Landers, California, earthquake Bulletin of the Seismological Society of America, June 1, 1994; 84(3): 817 - 825. [Abstract] [PDF]

				H. KANAMORI, P. C. JENNINGS, S. K. SINGH, and L. ASTIZ Estimation of strong ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap Bulletin of the Seismological Society of America, June 1, 1993; 83(3): 811 - 829. [Abstract] [PDF]