[en] This report describes the progress being made in event location using a single 3-component station. In this study locations are obtained using a backazimuth determined by the particle motion of Pn and a distance determined by differential travel times between Pn, Pg, and Lg relative to a master event of known location. The data set used consists of the seismic signals from 11 nuclear events at the Nevada Test Site (NTS) and recorded at the four Lawrence Livermore National Laboratory (LLNL) seismic stations: Elko, Kanab, Landers, and Mina. The stations range from 230 km to 400 km away from the events. The local magnitude (M_L) of the events range from 3.7 to 5.6 with the small events barely visible over the microseisms. All calculations and observations are made after the events have been filtered between 0.3 and 6 Hz. The results of this analysis show that backazimuth can be determined to within +- 5₀ of the true backazimuth, about 90% of the time, after systematic variations are taken out

[en] Methods of seismic detection of nuclear events are investigated in the Government sponsored research reports. Data acquisition techniques, data processing, and data collection sources are reviewed. The updated bibliography contains 246 abstracts, 101 of which are new entries to the previous edition. See also NTIS/PS-76/0208, Volume 2, 1973-1974 and NTIS/PS-76/0207, Volume 1, 1970-1972

[en] The site and intensity of nuclear weapons tests can be reliably determined by measurement and suitable interpretation of seismic waves. A seismic focus is up to 20 times larger than the destruction zone of a comparably strong explosion, so that a seismic event will last longer by one order of magnitude than an explosion. Nuclear weapons tests induce much more high-frequency vibrations than a seismic event, and a seismic event normally proceeds in a series of subsequent shocks. Diaphragms applied in the range 10 to 30 Hz considerably improve the signal-to-noise ratio of systems for the detection of nuclear weapons tests. (orig./DG)

[en] Since 1969, a consistent discrepancy in seismic magnitudes of nuclear detonations at NTS compared with magnitudes of detonations elsewhere in the world has been observed. This discrepancy can be explained in terms of a relatively high seismic attenuation for compressional waves in the upper mantle beneath the NTS and in certain other locations. A correction has been developed for this attenuation based on a relationship between the velocity of compressional waves at the top of the earth's mantle (just beneath the Mohorovicic discontinuity) and the seismic attenuation further down in the upper mantle. Our new definition of body-wave magnitude includes corrections for attenuation in the upper mantle at both ends of the teleseismic body-wave path. These corrections bring the NTS oservations into line with measurements of foreign events, and enable one to make more reliable estimates of yields of underground nuclear explosions, wherever the explosion occurs

[en] A 1976 treaty between the United States and the Soviet Union permits a local seismic network to be deployed at the site of a peaceful nuclear explosion to monitor the event. Criteria for the design and selection of the data-acquisition equipment for such a network are provided. Constraints imposed by the protocol of the treaty, the environment, and the expected properties of seismic signals (based on experiences at the Nevada Test Site) are discussed. Conclusions are drawn about the desired operating mode. Criteria for a general seismic instrumentation system are described

No abstract available

[en] The structure and characteristics of rugged photomultiplier tube are introduced. It can be used in adverse circumstances

[en] Sandia Laboratories is developing for the U.S. Army a Ground-Based Nuclear Burst Detection System to provide pertinent information for its field commanders and higher authorities. The equipment must operate in all kinds of weather and produce very low false alarms under all types of conditions. With these requirements, a study of the effects during thunderstorms, which includes thousands of lightning flashes, was conducted. The results of these studies were that, with suitable discrimination, the system had no false alarms during a period of high thunderstorm activity in the Albuquerque area for the time from September 13 to October 3, 1977. Data and plots are included of those false alarms that were recorded before the final discriminants were implemented to provide an inventory of waveshapes for additional analysis

[en] This paper analyses a existing problem of bistation bearing-only locating arithmetic on the engineering project. The arithmetic of solving problems are advanced and explained. (authors)

No abstract available