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Seismic Source Descriptions of Underground Explosions and a Depth Discriminate

Helmberger, D. V. and Harkrider, D. G. (1972) Seismic Source Descriptions of Underground Explosions and a Depth Discriminate. Geophysical Journal International, 31 (1-3). pp. 45-66. ISSN 0956-540X. doi:10.1111/j.1365-246X.1972.tb02358.x.

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Synthetic seismograms of both body waves and Rayleigh waves are used to determine the radiation field of a few large contained underground explosions. A number of possible source descriptions are investigated. A reduced displacement potential of the form, ø(t) = ø_0t^ξ exp(-ηt), fits the long- and short-period data. The source parameters appropriate for the Boxcar event are ξ = 0·5 and η = 0·15. Synthetic PL and Rayleigh waves are compared with observations from a number of different size events to determine the dependence of η on yield. The amplitude of the long period synthetic body wave responses at ranges greater than about 12° increases rapidly as the source depth is increased. Thus the difference in spectral properties of explosions and earthquakes can be largely explained by the depth effect. The theoretical ratio SP/LP, that is the short period divided by the long-period amplitude, is computed from 12 to 25° for the Johnson upper mantle model and the Boxcar source. A study of an earthquake which cannot be distinguished from an explosion using the m_b vs. M_s criterion is investigated by the SP/LP discriminate.

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Additional Information:© 1972 Royal Astronomical Society. Received in original form 1972 March 21. Received 1972 August 21. The authors were assisted by Gladys Engen and Shirley Fisher in the computations and digitization of seismograms. This research was supported by the Advanced Research Projects Agency of the Department of Defence and was monitored by the Air Force Office of Scientific Research under Contract Nos. F44620-69-C-0067 and F44620-70-C-0120.
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Advanced Research Projects Agency (ARPA)UNSPECIFIED
Air Force Office of Scientific Research (AFOSR)F44620-69-C-0067
Air Force Office of Scientific Research (AFOSR)F44620-70-C-0120
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Caltech Division of Geological and Planetary Sciences2152
Issue or Number:1-3
Record Number:CaltechAUTHORS:20151029-082401562
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Official Citation:D. V. Helmberger and D. G. Harkrider Seismic Source Descriptions of Underground Explosions and a Depth Discriminate Geophys. J. Int. (1972) 31 (1-3): 45-66 doi:10.1111/j.1365-246X.1972.tb02358.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61708
Deposited By: Tony Diaz
Deposited On:29 Oct 2015 17:40
Last Modified:10 Nov 2021 22:52

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