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Science 25 July 1986:
Vol. 233. no. 4762, pp. 449 - 453
DOI: 10.1126/science.233.4762.449
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Articles

The 1985 Central Chile Earthquake: A Repeat of Previous Great Earthquakes in the Region?

D. COMTE 1, A. EISENBERG 1, E. LORCA 2, M. PARDO 1, L. PONCE 3, R. SARAGONI 4, S. K. SINGH 5, and G. SuÁREZ 3

1 Departamento de Geología y Geofisica, Universidad de Chile, Santiago, Chile.
2 Instituto Hidrográfico de la Armada, Valparaíso, Chile.
3 Instituto de Geofisica, Ciudad Universitaria, Universidad Nacional Autónoma de México, 04510 México, DF.
4 Departamento de Ingenierfa, Civil, Universidad de Chile, Santiago, Chile.
5 Instituto de Geofisica and Instituto de Ingeniería, Ciudad Universitaria, Universidad Nacional Autónoma de México, 04510 México, DF.

A great earthquake (surface-wave magnitude, 7.8) occurred along the coast of central Chile on 3 March 1985, causing heavy damage to coastal towns. Intense foreshock activity near the epicenter of the main shock occurred for 11 days before the earthquake. The aftershocks of the 1985 earthquake define a rupture area of 170 by 110 square kilometers. The earthquake was forecast on the basis of the nearly constant repeat time (83 ± 9 years) of great earthquakes in this region. An analysis of previous earthquakes suggests that the rupture lengths of great shocks in the region vary by a factor of about 3. The nearly constant repeat time and variable rupture lengths cannot be reconciled with time- or slip-predictable models of earthquake recurrence. The great earthquakes in the region seem to involve a variable rupture mode and yet, for unknown reasons, remain periodic. Historical data suggest that the region south of the 1985 rupture zone should now be considered a gap of high seismic potential that may rupture in a great earthquake in the next few tens of years.

Submitted on August 26, 1985
Accepted on March 21, 1986


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Coastal deformation and great subduction earthquakes, Isla Santa Maria, Chile (37{degrees}S).
D. Melnick, B. Bookhagen, H. P. Echtler, and M. R. Strecker (2006)
Geological Society of America Bulletin 118, 1463-1480
   Abstract »    Full Text »    PDF »
Wide-band analysis of the 3 March 1985 central Chile earthquake: Overall source process and rupture history.
C. Mendoza, S. Hartzell, and T. Monfret (1994)
Bulletin of the Seismological Society of America 84, 269-283
   Abstract »    PDF »
Seismic moment catalog of large shallow earthquakes, 1900 to 1989.
J. F. PACHECO and L. R. SYKES (1992)
Bulletin of the Seismological Society of America 82, 1306-1349
   Abstract »    PDF »
Simulation of strong ground motions recorded during the 1985 Michoacan, Mexico and Valparaiso, Chile earthquakes.
P. SOMERVILLE, M. SEN, and B. COHEE (1991)
Bulletin of the Seismological Society of America 81, 1-27
   Abstract »    PDF »


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