HC Deb 15 November 1962 vol 667 c72W
Mr. Lubbock

asked the Minister of Defence how many of the seismic events which took place in the Union of Soviet Socialist Republics between 30th September, 1961, and 30th September, 1962, could not be positively identified as of nuclear or natural origin, according to the information available to Her Majesty's Government.

Mr. Thorneycroft

Although some seismic events can already be identified as earthquakes there is no known method of positively identifying every seismic event. United Kingdom surveillance of seismic events in the Soviet Union is not comprehensive, but our information supports the view that even with the full international monitoring system which the West has proposed at Geneva there would remain 50–75 unidentified events in the Soviet Union each year.