Travel time curves and isochron maps from the Borovoye digital archive for the Nevada and Semipalatinsk Nuclear Test Sites

Abstract

The paper presents generalized parameters of digital seismograms of the Borovoye Geophysical Observatory (BRVK). The seismograms were obtained after reformatting the archive of the Institute of Geosphere Dynamics (IDG RAS). For this research, we consider looking at the most representative entries – underground nuclear explosions (UNE). The particular interest is the analysis of the P-wave travel times at the regional distances Δ≈5–7° and Δ≈89–91°. These deep paths cross the boundaries of the Earth crust, mantle and outer core. There are UNE digital records at the Semipalatinsk Test Site (Δ_STS ≈5.56–6.27°) and at the Nevada Test Site (Δ_NTS≈89.77–90.15°). For this reason, we use UNEs from STS and NTS from 1967 to 1992. UNEs locations and magnitudes are taken from published open sources. The results for P-wave travel time curves on the BRVK – NTS and BRVK – STS paths and the isochron maps are obtained. The linear functions for travel time curves are defined by the linear regression. The resulting seismic travel time curves for P waves are compared to AK135. Because global one-dimensional seismic reference models are non-unique solution to regional seismic data, in terms of physical structure. The results help identify seismic wave velocities at the source-receiver travel paths and character of geologic media. Such physical models could significantly facilitate physical interpretation of seismic structures in the area of Central Asia (e.g. Tien Shan) and global.