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A slow earthquake

Kanamori, Hiroo and Stewart, Gordon S. (1979) A slow earthquake. Physics of the Earth and Planetary Interiors, 18 (3). pp. 167-175. ISSN 0031-9201. doi:10.1016/0031-9201(79)90112-2.

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Anomalous earthquakes such as creep events, tsunami earthquakes and silent earthquakes have been reported in the recent literature. In this paper we discuss an anomalous “slow earthquake” that occurred on June 6, 1960 in southern Chile. Although the surface-wave magnitude of this event is only 6.9, it excited anomalously large long-period multiple surface waves with a seismic moment of 5.6 · 10^(27) dyn cm. The Benioff long-period seismogram of this earthquake recorded at Pasadena shows an extremely long, about 1.5–2 h coda of Rayleigh waves, with a period of 10–25 s. The coda length for other events with a comparable magnitude which occurred in the same region is about 10 min. This observation suggests that the long coda length is due to a long source rupture process which lasted at least 1 h. Although at least 15 distinct events can be identified in the coda, no short-period body waves were recorded corresponding to these, except for the first one. These results suggest that a relatively small (Ms ≅ 6.9) earthquake triggered a series of slow events; the duration of the whole sequence being longer than 1 h. This event probably occurred on a transform fault on the extension of the Chile Rise and provides important information regarding the nature of the transform fault.

Item Type:Article
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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1979 Elsevier Scientific Publishing Company. Received June 21, 1978; accepted for publication July 17, 1978. We would like to thank the seismographic station at De Bilt, The Netherlands, and Tsukuba, Japan, for sending us the seismograms used in the present study. This research was supported by grants from the Division of Earth Sciences, National Science Foundation, NSF Grants (EAR76-14262 and EAR77-13641). Contribution No. 3097, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125
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Caltech Division of Geological and Planetary Sciences3097
Issue or Number:3
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Official Citation:Hiroo Kanamori, Gordon S. Stewart, A slow earthquake, Physics of the Earth and Planetary Interiors, Volume 18, Issue 3, March 1979, Pages 167-175, ISSN 0031-9201, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58156
Deposited By: Tony Diaz
Deposited On:10 Jun 2015 18:27
Last Modified:10 Nov 2021 22:00

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