Evidence of tectonic release in long-period S waves from underground nuclear explosions at the Novaya Zemlya test sites

Abstract Evidence of tectonic release produced by underground nuclear explosions at Novaya Zemlya is present in teleseismic, long-period S waves. SH waveforms from representative events at the Southern and Northern Novaya Zemlya test sites were modeled to determine the SH radiation patterns. Long-period P and SV waves were also investigated to further constrain the equivalent double-couple orientation of the tectonic release. Events within each test site have similar faulting mechanisms, but there are definite differences in the tectonic release orientation between the two sites. The southern test site double-couple orientation is either vertical strike slip or 45°-dipping thrust, while the northern test site has an oblique-normal dip slip orientation. The limited resolution of SH signals and complexity of the observed SV waveforms, along with uncertainties in the absolute explosion source strengths and t *, prevent unique solutions for both test sites. Assuming a strike slip orientation, the 27 October 1973 Southern Novaya Zemlya event has the largest tectonic release moment (1.6 × 10 24 dyne-cm) and 14 October 1969 northern event has the smallest moment (0.9 × 10 23 dyne-cm) of the 12 events studied. The ratio of tectonic release moment to explosion strength varies by as much as a factor of 3 at the northern test site and by a factor of 2 at the southern site. The variability of the tectonic release orientation and strength at the two test sites allows us to address the question of whether tectonic release affects yield estimation.

[1]  Paul W. Pomeroy,et al.  Surface wave radiation patterns for underground nuclear explosions and small‐magnitude earthquakes , 1963 .

[2]  M. Nafi Toksöz,et al.  Tectonic Strain Release by Underground Nuclear Explosions and its Effect on Seismic Discrimination , 1972 .

[3]  M. Toksöz,et al.  Determination of source parameters by amplitude equalization of seismic surface waves: 2. Release of tectonic strain by underground nuclear explosions and mechanisms of earthquakes , 1965 .

[4]  L. J. Burdick,et al.  Time functions appropriate for nuclear explosions , 1979, Bulletin of the Seismological Society of America.

[5]  T. Wallace,et al.  EVIDENCE OF TECTONIC RELEASE FROM UNDERGROUND NUCLEAR EXPLOSIONS IN LONG-PERIOD S WAVES , 1985 .

[6]  O. Nuttli.  TRAVEL TIMES AND AMPLITUDES OF S WAVES FROM NUCLEAR EXPLOSIONS IN NEVADA. , 1969 .

[8]  C. Langston,et al.  A WKBJ spectral method for computation of SV synthetic seismograms in a cylindrically symmetric medium , 1985 .

[9]  Ola Dahlman,et al.  Monitoring Underground Nuclear Explosions , 1977 .

[10]  Yi-Ben Tsai,et al.  Mechanism of Love‐Wave excitation by explosive sources , 1972 .

[11]  Tomowo Hirasawa.  Radiation patterns of S waves from underground nuclear explosions , 1971 .

[12]  C. Sammis,et al.  Seismic radiation from explosions in prestressed media and the measurement of tectonic stress in the Earth , 1970 .

[13]  H. K. Shah,et al.  Magnitude/yield variability in the western United States: analysis of the Rulison/Gasbuggy anomaly. Final report 1 Dec 81-30 Nov 82 , 1983 .

[14]  Walter I. Futterman,et al.  Dispersive body waves , 1962 .

[15]  K. Aki,et al.  Near-field and far-field seismic evidences for triggering of an earthquake by the Benham explosion , 1969 .

[16]  Keiiti Aki,et al.  Seismic source function for an underground nuclear explosion : 10F, 3T, 48R Seismol. Soc. Amer. Bull. V64, N1, Feb. 1974, P131–148 , 1974 .

[17]  L. Sykes,et al.  Yields of Soviet underground nuclear explosions at Novaya Zemlya, 1964-1976, from seismic body and surface waves. , 1986, Proceedings of the National Academy of Sciences of the United States of America.

[18]  D. V. Seggern.  The effects of radiation patterns on magnitude estimates , 1970 .

[19]  T. Lay.  Estimating explosion yield by analytical waveform comparison , 1985 .

[20]  Rhett Butler,et al.  Teleseismic short-period amplitudes: Source and receiver variations , 1980 .

[21]  Thorne Lay,et al.  Source models and yield-scaling relations for underground nuclear explosions at Amchitka Island , 1984 .

[22]  E. A. Flinn,et al.  A Comparative Study of the Elastic Wave Radiation from Earthquakes and Underground Explosions , 1972 .

[23]  Charles B. Archambeau,et al.  The Theory of Stress Wave Radiation from Explosions in Prestressed Media , 1972 .

[24]  T. Lay,et al.  The effects of tectonic release on short-period P waves from NTS explosions , 1984 .

[25]  F. Press,et al.  Release of tectonic strain by underground nuclear explosions , 1962 .