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Science 2 December 1994:
Vol. 266. no. 5190, pp. 1547 - 1551
DOI: 10.1126/science.266.5190.1547
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Articles

Teleseismic Search for Slow Precursors to Large Earthquakes

Pierre F. Ihmlé 1 and Thomas H. Jordan 2

1 Institut de Physique du Globe, 4 Place Jussieu, Paris Cedex 75252, France
2 Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Some large earthquakes display low-frequency seismic anomalies that are best explained by episodes of slow, smooth deformation immediately before their high-frequency origin times. Analysis of the low-frequency spectra of 107 shallow-focus earthquakes revealed 20 events that had slow precursors (95 percent confidence level); 19 were slow earthquakes associated with the ocean ridge-transform system, and 1 was a slow earthquake on an intracontinental transform fault in the East African Rift system. These anomalous earthquakes appear to be compound events, each comprising one or more ordinary (fast) ruptures in the shallow seismogenic zone initiated by a precursory slow event in the adjacent or subjacent lithosphere.

Submitted on July 29, 1994
Accepted on September 29, 1994


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Bulletin of the Seismological Society of America 93, 948-952
Low-Frequency Properties of Intermediate-Focus Earthquakes.
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Lack of Precursory Slip to the 1999 Hector Mine, California, Earthquake as Constrained by InSAR.
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Constraints on Slow Earthquake Dynamics from a Swarm in Central Italy.
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Self-consistent retrieval of source parameters using mantle waves.
K. Gouget, P. F. Ihmle, J. Campos, and J.-P. Montagner (1998)
Bulletin of the Seismological Society of America 88, 995-1002
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Seismic Evidence for an Earthquake Nucleation Phase.
W. L. Ellsworth, W. L. Ellsworth, and G. C. Beroza (1995)
Science 268, 851-855
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