Aftershocks caused by the Novya Zemlya explosion on October 27, 1973
In the autumn of 1973 seismic signals were recorded at Novaya Zemlya from three undenground nuclear explosions in the Arctic Ocean. One of these explosions was followed by a series of ten small events all of which occurred within 4 hr of the explosion. The locations of the explosions and the after events were determined based on data from Nordic and North American stations and discrimination results obtained at the Swedish Hagfors Observatory. The epicenters were obtained by a joint location technique utilizing arrival times of seismic P and S phases. Two of the explosions were located about 200 km south of the main test site of Novaya Zemlya, where the third explosion was fired. No surface waves were detected for the after events. The after event signals were complex compared with the simple pulselike waveforms of the explosion, and the explosions and after events appeared to represent different types of seismic sources. Two different types of aftershock activity are known. The first is associated with cavity deterioration and the events are located in the immediate vicinity of the cavity; they are observed soon after the explosion and continue until the cavity completely collapses. The second type represents explosion stimulated tectonic events, Which may occur at distances >10 km from the explosion and have been Observed months later. The fectonic events appear to be generally weaker than those related to cavity deterioration. From the observations it is concluded that the observed signals came from events related to cavity deterioration; but no event that could be associated with complete collapse of the cavity has so far been observed. (UK)
- Research Organization:
- Foersvarets Forskningsanstalt, Stockholm
- NSA Number:
- NSA-29-029274
- OSTI ID:
- 4299982
- Journal Information:
- Nature (London), v. 247, no. 5441, pp. 450-452, Journal Name: Nature (London), v. 247, no. 5441, pp. 450-452; ISSN NATUA
- Country of Publication:
- United Kingdom
- Language:
- English
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