| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Earth and Space Sciences University of California, Los Angeles, California 90095
Department of Physics and Institute of Geophysics and Planetary Physics University of California, Los Angeles, California 90095
Abstract
The analysis of seismograms from 32 aftershocks recorded by 98 seismic stations installed after the Northridge earthquake in the San Fernando Valley, the Santa Monica Mountains, and Santa Monica, California, indicates that the enhanced damage in Santa Monica is explained in the main by focusing due to a lens structure at a depth of several kilometers beneath the surface and having a finite lateral extent. The diagnosis was made from the observation of late-arriving S phases with large amplitudes, localized in the zones of large damage. The azimuths and angles of incidence of the seismic rays that give rise to the greatest focusing effects correspond to radiation that would have emerged from the lower part of the rupture surface of the mainshock. Thus the focusing and, hence, the large damage in Santa Monica were highly dependent on the location of the Northridge event, and an earthquake of similar size, located as little as one source dimension away, would not be likely to repeat this pattern. We show from coda wave analysis that the influence of surface geology as well as site effects on damage in Santa Monica is significantly smaller than are the focusing effects.
This article has been cited by other articles:
|
|
 |
|
  F. Pettenati and L. Sirovich Validation of the Intensity-Based Source Inversions of Three Destructive California Earthquakes Bulletin of the Seismological Society of America, October 1, 2007; 97(5): 1587 - 1606. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Chen, L. Zhao, and T. H. Jordan Full 3D Tomography for the Crustal Structure of the Los Angeles Region Bulletin of the Seismological Society of America, August 1, 2007; 97(4): 1094 - 1120. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Maresca, D. Galluzzo, and E. Del Pezzo H/V Spectral Ratios and Array Techniques Applied to Ambient Noise Recorded in the Colfiorito Basin, Central Italy Bulletin of the Seismological Society of America, April 1, 2006; 96(2): 490 - 505. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Husker, M. D. Kohler, and P. M. Davis Anomalous Seismic Amplitudes Measured in the Los Angeles Basin Interpreted as a Basin-Edge Diffraction Catastrophe Bulletin of the Seismological Society of America, February 1, 2006; 96(1): 147 - 164. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
An Efficient Finite-Difference Method for Simulating 3D Seismic Response of Localized Basin Structures Bulletin of the Seismological Society of America, October 1, 2004; 94(5): 1690 - 1705.
|
|
|
|
|
|
D. Komatitsch, Q. Liu, J. Tromp, P. Suss, C. Stidham, and J. H. Shaw Simulations of Ground Motion in the Los Angeles Basin Based upon the Spectral-Element Method Bulletin of the Seismological Society of America, February 1, 2004; 94(1): 187 - 206. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Amplification of Seismic Waves by the Seattle Basin, Washington State Bulletin of the Seismological Society of America, April 1, 2003; 93(2): 533 - 545.
|
|
|
|
|
|
Separation of Site Effects and Structural Focusing in Santa Monica, California: A Study of High-Frequency Weak Motions from Earthquakes and Blasts Recorded during the Los Angeles Region Seismic Experiment Bulletin of the Seismological Society of America, December 1, 2002; 92(8): 3134 - 3151.
|
|
|
|
|
|
Edge-Diffracted 1-Sec Surface Waves Observed in a Small-Size Intramountain Basin (Colfiorito, Central Italy) Bulletin of the Seismological Society of America, December 1, 2001; 91(6): 1851 - 1866.
|
|
|
|
|
|
Site Response, Shallow Shear-Wave Velocity, and Damage in Los Gatos, California, from the 1989 Loma Prieta Earthquake Bulletin of the Seismological Society of America, June 1, 2001; 91(3): 468 - 478.
|
|
|
|
|
|
Observations of Basin Ground Motions from a Dense Seismic Array in San Jose, California Bulletin of the Seismological Society of America, February 1, 2001; 91(1): 1 - 12.
|
|
|
|
|
|
Three-Dimensional Simulations of Ground Motions in the Seattle Region for Earthquakes in the Seattle Fault Zone Bulletin of the Seismological Society of America, October 1, 2000; 90(5): 1251 - 1267.
|
|
|
|
 |
|
 P. M. Davis, J. L. Rubinstein, K. H. Liu, S. S. Gao, and L. Knopoff Northridge Earthquake Damage Caused by Geologic Focusing of Seismic Waves Science, September 8, 2000; 289(5485): 1746 - 1750. [Abstract] [Full Text]
|
|
|
|
|
|
S. Kinoshita A stochastic method for investigating site effects by means of a borehole array--SH and Love waves Bulletin of the Seismological Society of America, April 1, 1999; 89(2): 484 - 500. [Abstract] [PDF]
|
|
|
|
|
|
R. D. Catchings, M. R. Goldman, W. H. K. Lee, M. J. Rymer, and D. J. Ponti Faulting apparently related to the 1994 Northridge, California, earthquake and possible co-seismic origin of surface cracks in Potrero Canyon, Los Angeles County, California Bulletin of the Seismological Society of America, December 1, 1998; 88(6): 1379 - 1391. [Abstract] [PDF]
|
|
|
|
|
|
F. Su, J. G. Anderson, and Y. Zeng Study of weak and strong ground motion including nonlinearity from the Northridge, California, earthquake sequence Bulletin of the Seismological Society of America, December 1, 1998; 88(6): 1411 - 1425. [Abstract] [PDF]
|
|
|
|
|
|
R. W. Graves, A. Pitarka, and P. G. Somerville Ground-motion amplification in the Santa Monica area: Effects of shallow basin-edge structure Bulletin of the Seismological Society of America, October 1, 1998; 88(5): 1224 - 1242. [Abstract] [PDF]
|
|
|
|
|
|
D. Komatitsch and J.-P. Vilotte The spectral element method: An efficient tool to simulate the seismic response of 2D and 3D geological structures Bulletin of the Seismological Society of America, April 1, 1998; 88(2): 368 - 392. [Abstract] [PDF]
|
|
|
|
|
|
S. Hartzell, S. Harmsen, A. Frankel, D. Carver, E. Cranswick, M. Meremonte, and J. Michael First-generation site-response maps for the Los Angeles region based on earthquake ground motions Bulletin of the Seismological Society of America, April 1, 1998; 88(2): 463 - 472. [Abstract] [PDF]
|
|
|
|
|
|
D. Jongmans, K. Pitilakis, D. Demanet, D. Raptakis, J. Riepl, C. Horrent, G. Tsokas, K. Lontzetidis, and P.-Y. Bard EURO-SEISTEST: Determination of the geological structure of the Volvi basin and validation of the basin response Bulletin of the Seismological Society of America, April 1, 1998; 88(2): 473 - 487. [Abstract] [PDF]
|
|
|
|
|
|
S. Hartzell, E. Cranswick, A. Frankel, D. Carver, and M. Meremonte Variability of site response in the Los Angeles urban area Bulletin of the Seismological Society of America, December 1, 1997; 87(6): 1377 - 1400. [Abstract] [PDF]
|
|
|
|
|
|
S. C. Harmsen Determination of site amplification in the Los Angeles urban area from inversion of strong-motion records Bulletin of the Seismological Society of America, August 1, 1997; 87(4): 866 - 887. [Abstract] [PDF]
|
|
|
|
|
|
S. Gao A Bayesian nonlinear inversion of seismic body-wave attenuation factors Bulletin of the Seismological Society of America, August 1, 1997; 87(4): 961 - 970. [Abstract] [PDF]
|
|
|
|
|
|
L. F. Bonilla, J. H. Steidl, G. T. Lindley, A. G. Tumarkin, and R. J. Archuleta Site amplification in the San Fernando Valley, California: Variability of site-effect estimation using the S-wave, coda, and H/V methods Bulletin of the Seismological Society of America, June 1, 1997; 87(3): 710 - 730. [Abstract] [PDF]
|
|
|
|
|
|
S. E. Hough and E. H. Field On the coherence of ground motion in the San Fernando Valley Bulletin of the Seismological Society of America, December 1, 1996; 86(6): 1724 - 1732. [Abstract] [PDF]
|
|
|
|
|
|
M. Meremonte, A. Frankel, E. Cranswick, D. Carver, and D. Worley Urban seismology--Northridge aftershocks recorded by multi-scale arrays of portable digital seismographs Bulletin of the Seismological Society of America, October 1, 1996; 86(5): 1350 - 1363. [Abstract] [PDF]
|
|
|
|
|
|
E. H. Field Spectral amplification in a sediment-filled Valley exhibiting clear basin-edge-induced waves Bulletin of the Seismological Society of America, August 1, 1996; 86(4): 991 - 1005. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
