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Temporal Variation of the Activity of Intermediate and Deep Focus Earthquakes

Abe, Katsuyuki and Kanamori, Hiroo (1979) Temporal Variation of the Activity of Intermediate and Deep Focus Earthquakes. Journal of Geophysical Research B, 84 (B7). pp. 3589-3595. ISSN 0148-0227. doi:10.1029/JB084iB07p03589.

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The temporal variation of the activity of intermediate and deep focus earthquakes for the period from 1904 to 1974 is investigated on the basis of a uniform body-wave magnitude scale. The m_b scale has been traditionally used for intermediate and deep focus earthquakes. However, the period of seismic waves and the Q function used for the magnitude determination have changed as a function of time, so that uniform evaluation of the activity is difficult. In this study, we used a body-wave magnitude m_B determined from the maximum amplitude of body waves recorded by broad-band or long-period instruments to investigate the temporal variation. For the period from 1904 to 1952, m_b values were calculated from the unpublished material of Gutenberg and Richter. For 1953 to 1958, m_B values were calculated from the amplitude and the period data in Gutenberg's unpublished file. For the period from 1959 to 1974, seismological bulletins from various stations were used to determine m_B. Consistency between the values of m_B calculated from these different sources was carefully checked. The temporal variation of the number of intermediate-deep events with m_B ≥ 7 is remarkably similar to that of shallow earthquakes with M_s ≥ 7. The temporal variation of the energy release in intermediate-deep earthquakes shows a maximum around 1910. The sum of the energy release curve of intermediate-deep and shallow earthquakes shows a good correlation with the amplitude of the Chandler wobble. The energy release becomes maximum at the depth of 350 and 600 km.

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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1976 American Geophysical Union. Received October 18, 1978; revised December 1, 1978; accepted December 1, 1978. First published: 10 July 1979. We thank Gordon Stewart for reviewing the manuscript. This research was supported by the Earth Sciences Section of the National Science Foundation, grant EAR77-13641. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California contribution 3125.
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Caltech Division of Geological and Planetary Sciences3125
Issue or Number:B7
Record Number:CaltechAUTHORS:20150610-065407607
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Official Citation:Abe, K., and H. Kanamori (1979), Temporal variation of the activity of intermediate and deep focus earthquakes, J. Geophys. Res., 84(B7), 3589–3595, doi:10.1029/JB084iB07p03589.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58142
Deposited On:10 Jun 2015 15:20
Last Modified:10 Nov 2021 22:00

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