Quick Search:    advanced search

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

This Article Figures Only Full Text Full Text (PDF) 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 Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Furumura, T. Articles by Singh, S. K. Search for Related Content GeoRef GeoRef Citation

Regional Wave Propagation from Mexican Subduction Zone Earthquakes: The Attenuation Functions for Interplate and Inslab Events

Earthquake Research Institute
University of Tokyo
1-1-1 Yayoi, Bunkyo-ku
113-0032, Japan
furumura{at}eri.u-tokyo.ac.jp
(T.F.)

Instituto de Geofísica
Universidad Nacíonal Autónoma de México
Ciudad Universitaria
Coyoacán, 04510, México D.F.
(S.K.S.)

The seismic waves from subduction zone earthquakes are significantly affected by the presence of 3D variation in crust and upper-mantle structure around the source area. These heterogeneous structures also profoundly modify the character of seismic waves as they propagate from the source area to regional distances. This is illustrated by studying shallow, interplate earthquakes along the Mexican subduction zone, and deeper, inslab, normal-faulting earthquakes in the subducted Cocos plate beneath Mexican mainland. The strong-motion recordings of these earthquakes are used to evaluate the character of wave propagation along the path between the source region and Mexico City. We compare the wavefield from two large earthquakes of different source type. During the shallow (H = 17 km), interplate, 1995 Guerrero earthquake (M_w 7.3), the Lg phase is the most prominent feature at regional distances of about 150 to a few hundred kilometers from the source. The presence of a lateral velocity gradient in the crust, caused by the subduction of the Cocos plate, enhances the Lg-wave amplitude, which is then amplified further in the Mexican volcanic belt by amplification in the low-velocity volcanic rocks. Both effects lead to very large ground motions along the path from the coast to the Mexican inland, in the frequency band from 0.2 to 4 Hz. However, for the deeper (H = 40 km), inslab, normal-faulting, 1999 Oaxaca earthquake (M_w 7.5), the amplitude of the Lg phase is too small to produce the abnormal wave propagation, and the direct S wave and its multiple SmS reflections between the free-surface and Moho show a simple attenuation with increasing distance. We compare these observations with numerical simulations of seismic-wave propagation using the Fourier spectral method. The results provide a key to the understanding of seismic-wave field generated by shallow interplate and deeper inslab earthquakes in a realistic 3D heterogeneous structure.

This article has been cited by other articles:

				G. M. Atkinson and M. Macias Predicted Ground Motions for Great Interface Earthquakes in the Cascadia Subduction Zone Bulletin of the Seismological Society of America, June 1, 2009; 99(3): 1552 - 1578. [Abstract] [Full Text] [PDF]

				H. Cruz-Jimenez, F. J. Chavez-Garcia, and T. Furumura Differences in Attenuation of Ground Motion Perpendicular to the Mexican Subduction Zone between Colima and Guerrero: An Explanation Based on Numerical Modeling Bulletin of the Seismological Society of America, February 1, 2009; 99(1): 400 - 406. [Abstract] [Full Text] [PDF]

				S. K. Singh, J. F. Pacheco, D. Garcia, and A. Iglesias An Estimate of Shear-Wave Q of the Mantle Wedge in Mexico Bulletin of the Seismological Society of America, February 1, 2006; 96(1): 176 - 187. [Abstract] [Full Text] [PDF]

				D. Garcia, S. K. Singh, M. Herraiz, M. Ordaz, and J. F. Pacheco Inslab Earthquakes of Central Mexico: Peak Ground-Motion Parameters and Response Spectra Bulletin of the Seismological Society of America, December 1, 2005; 95(6): 2272 - 2282. [Abstract] [Full Text] [PDF]

				Inslab Earthquakes of Central Mexico: Q, Source Spectra, and Stress Drop Bulletin of the Seismological Society of America, June 1, 2004; 94(3): 789 - 802.

				A. F. McNeill, M. G. Bostock, G. C. Rogers, and J. C. Shragge The Effect of Forearc Mantle Serpentinization on Ground Motions from Megathrust and Intraslab Events in the Cascadia Subduction Zone Bulletin of the Seismological Society of America, February 1, 2004; 94(1): 147 - 154. [Abstract] [Full Text] [PDF]

				T.-W. Chung and K. Lee A Study of High-Frequency Q (super -1) Lg in the Crust of South Korea Bulletin of the Seismological Society of America, June 1, 2003; 93(3): 1401 - 1406. [Abstract] [Full Text] [PDF]