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 (3) Citing Articles via Google Scholar Google Scholar Articles by Brune, J. N. Articles by Zeng, Y. Search for Related Content GeoRef GeoRef Citation

Precarious Rock and Overturned Transformer Evidence for Ground Shaking in the M_s 7.7 Kern County Earthquake: An Analog for Disastrous Shaking from a Major Thrust Fault in the Los Angeles Basin

¹ Seismological Laboratory MS 174
University of Nevada, Reno
Reno, Nevada 98557
rasool{at}seismo.unr.edu
 (J.N.B., A.A., Y.Z.)

² Kentucky Geological Survey
University of Kentucky
Lexington, Kentucky 40506
 (B.S.)

Precariously balanced rocks and overturned transformers in the vicinity of the White Wolf fault provide constraints on ground motion during the 1952 M_s 7.7 Kern County earthquake, a possible analog for an anticipated large earthquake in the Los Angeles basin (Shaw et al., 2002; Dolan et al., 2003). On the northeast part of the fault preliminary estimates of ground motion on the footwall give peak accelerations considerably lower than predicted by standard regression curves. On the other hand, on the hanging-wall, there is evidence of intense ground shattering and lack of precarious rocks, consistent with the intense hanging-wall accelerations suggested by foam-rubber modeling, numerical modeling, and observations from previous thrust fault earthquakes. There is clear evidence of the effects of rupture directivity in ground motions on the hanging-wall side of the fault (from both precarious rocks and numerical simulations).

On the southwest part of the fault, which is covered by sediments, the thrust fault did not reach the surface ("blind" thrust). Overturned and damaged transformers indicate significant transfer of energy from the hanging wall to the footwall, an effect that may not be as effective when the rupture reaches the surface (is not "blind"). Transformers near the up-dip projection of the fault tip have been damaged or overturned on both the hanging-wall and footwall sides of the fault. The transfer of energy is confirmed in a numerical lattice model and could play an important role in a similar situation in Los Angeles. We suggest that the results of this study can provide important information for estimating the effects of a large thrust fault rupture in the Los Angeles basin, specially given the fact that there is so little instrumental data from large thrust fault earthquakes.

This article has been cited by other articles:

				H. Kaneda, T. Nakata, H. Tsutsumi, H. Kondo, N. Sugito, Y. Awata, S. S. Akhtar, A. Majid, W. Khattak, A. A. Awan, et al. Surface Rupture of the 2005 Kashmir, Pakistan, Earthquake and Its Active Tectonic Implications Bulletin of the Seismological Society of America, April 1, 2008; 98(2): 521 - 557. [Abstract] [Full Text] [PDF]

				B. Shi and J. N. Brune Characteristics of Near-Fault Ground Motions by Dynamic Thrust Faulting: Two-Dimensional Lattice Particle Approaches Bulletin of the Seismological Society of America, December 1, 2005; 95(6): 2525 - 2533. [Abstract] [Full Text] [PDF]