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 HASEGAWA, H. S. Articles by KANAMORI, H. Search for Related Content GeoRef GeoRef Citation

Source mechanism of the magnitude 7.2 Grand Banks earthquake of November 1929: Double couple or submarine landslide?

GEOPHYSICS DIVISION GEOLOGICAL SURVEY OF CANADA, OTTAWA, ONTARIO K1A 0Y3, Canada
DIVISION OF GEOLOGICAL AND PLANETARY SCIENCES SEISMOLOGICAL LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY, PASADENA, CALIFORNIA 91125

Abstract

We have examined P, S, and surface waves derived from seismograms that we collected for the 1929 Grand Banks, Canada, earthquake. This event is noteworthy for the sediment slide and turbidity current that broke the trans-Atlantic cables and for its destructive tsunami. Both the surface-wave magnitude, M_S, and the body-wave magnitude, m_B, calculated from these seismograms are 7.2. Fault mechanisms previously suggested for this event include a NW-SE-striking strike-slip mechanism and an approximately E-W-striking thrust mechanism. In addition, because of the presence of an extensive area of slump and turbidity current, there exists the possibility that sediment slumping could also be a primary causative factor of this event. We tested these fault models and a horizontal single-force (oriented N5°W) model representing a sediment slide against our data. Among these models, only the single-force model is consistent with the P-, S-, and surface-wave data. Our data, however, do not preclude fault models which were not tested. From the spectral data of Love waves at a 50-sec period, we estimated the magnitude of the single force to be about 1.4 x 10²⁰ dynes. From this value, we estimated the total volume of sedimentary slumping to be about 5.5 x 10¹¹ m³, which is approximately 5 times larger than a recent estimate of volume from in situ measurements. The difference in estimates of overall volume is likely due to a combination of the inherent difficulty in estimating accurately the displaced sediments from in situ measurements, and of inadequacy of the seismic model; or perhaps because not only the slump but also a tectonic earthquake could have been the cause of this event and contributed significantly to the waveforms studied.

This article has been cited by other articles:

				J. Deparis, D. Jongmans, F. Cotton, L. Baillet, F. Thouvenot, and D. Hantz Analysis of Rock-Fall and Rock-Fall Avalanche Seismograms in the French Alps Bulletin of the Seismological Society of America, August 1, 2008; 98(4): 1781 - 1796. [Abstract] [Full Text] [PDF]

				L. Swafford and S. Stein Limitations of the short earthquake record for seismicity and seismic hazard studies Geological Society of America Special Papers, January 1, 2007; 425(0): 49 - 58. [Abstract] [Full Text] [PDF]

				S. Master Pangaean megalineaments: geophysical indications for the existence of Laurentian counterparts of the 6000 km Trans-Saharan Tibesti Lineament, and implications for lithospheric tectonics and mineral deposits South African Journal of Geology, December 1, 2006; 109(4): 503 - 514. [Abstract] [Full Text] [PDF]

				Seismic Signals Associated with Landslides and with a Tsunami at Stromboli Volcano, Italy Bulletin of the Seismological Society of America, October 1, 2004; 94(5): 1850 - 1867.

				N. W. Driscoll, J. K. Weissel, and J. A. Goff Potential for large-scale submarine slope failure and tsunami generation along the U.S. mid-Atlantic coast Geology, May 1, 2000; 28(5): 407 - 410. [Abstract] [Full Text] [PDF]

				M. Assumpcao Seismicity and stresses in the Brazilian passive margin Bulletin of the Seismological Society of America, February 1, 1998; 88(1): 160 - 169. [Abstract] [PDF]

				W.-Y. Chung and H. Gao The Greenland earthquake of 11 July 1987 and postglacial fault reactivation along a passive margin Bulletin of the Seismological Society of America, August 1, 1997; 87(4): 1058 - 1068. [Abstract] [PDF]

				A. L. Bent A complex double-couple source mechanism for the Ms 7.2 1929 Grand Banks earthquake Bulletin of the Seismological Society of America, August 1, 1995; 85(4): 1003 - 1020. [Abstract] [PDF]

				D. Weichert, R. B. Horner, and S. G. Evans Seismic signatures of landslides: The 1990 Brenda Mine collapse and the 1965 hope rockslides Bulletin of the Seismological Society of America, October 1, 1994; 84(5): 1523 - 1532. [Abstract] [PDF]

				F. A. DAHLEN Single-force representation of shallow landslide sources Bulletin of the Seismological Society of America, February 1, 1993; 83(1): 130 - 143. [Abstract] [PDF]

				J. F. PACHECO and L. R. SYKES Seismic moment catalog of large shallow earthquakes, 1900 to 1989 Bulletin of the Seismological Society of America, June 1, 1992; 82(3): 1306 - 1349. [Abstract] [PDF]