Deep seismiC sounding was proposed by G. A. Gamburtsev and developed under his guid ance during the period 1948-1955 at the Institute of Physics of the Earth of the Academy of Sciences of the USSR. During that period also, the first geophysical results concerning the deep structure of the earth's crust in several regions in Tien-Shan, the Pamir, and Turkmenia were observed. Beginning with 1956, the deep seismic sounding method has been used widely by geo physical research groups as well as by geophysical service organizations for regional studies in the USSR. Descriptions of this work have been given in reports by Yu. N. Godin, V. V. Fedynskii, D. N. Kazanli, and others. New variants of the deep seismic sounding method have been developed; continuous profiling (Yu. N. Godin, and others), and point soundings (N. N. Puzyrev, and others). Deep seismic soundings have been carried on outside of Russia also, and studies have been carried out on the use of the deep seismic sounding method in marine applications (E. I. Gal'perin, S. M. Zverev, 1. P. Kosminskaya, Yu. P. Neprochnov, and others). OVer the past decade, the deep seismic sounding method has joined the suite of geo physical studies as a highly detailed method for studying the earth's crust and upper mantle to depths of 50 to 100 km on land, and of 15 to 25 km in the deep oceans.

Developments in Geotectonics 8: The Structure of the Earth's Crust Based on Seismic Data covers the papers presented at an International Upper Mantle Committee (lUMC) symposium called ""Crustal Structure Based on Seismic Data"", held on July 30-31, 1971. The book focuses on the structure, composition, and characteristics of the earth's crust. The selection first offers information on the crustal structure of Central and Southeastern Europe by data of explosion seismology; structure of the earth's crust on the territory of the U.S.S.R.; and seismic studies of low-velocity layers and horizontal inhomogeneities within the crust and upper mantle on the territory of the U.S.S.R. The text also takes a look at the deep seismic investigations in the Baikal rift zone and crust of the arctic seas of Eurasia. Discussions focus on peculiarities of crustal structure, structure of the uppermost mantle, and method of investigation. The publication takes a look at the crustal structure of Japan as derived from explosion seismic data; crustal structure in the Matsushiro earthquake swarm area; and Soviet seismic studies of the earth's crust in the Pacific Ocean during the International Upper Mantle Project. The selection is a dependable source of information for readers interested in the structure of the earth's crust.

The translation is a summary of complex data on the earth's crust and upper mantle. In the examination of the data on the various regions of the terrestrial globe (characteristics of the gravity, magnetic, seismic, thermal and electric fields of the earth) and the comparison between them and the structure of the crust, the author reveals the specific features of the different geological structures and determines the diagnostic significance of the geophysical data. Much attention is given to the crustal structure of the oceanic areas. A description of the general characteristics of the relief and the physical properties of the upper mantle is given in the last section of the book, where the physical map of the upper mantle is given in the last section of the book, where the physical map of the upper mantle is presented. In conclusion, a review is given of the projects of ultradeep scientific boring in the Pacific ocean, territory of the USSR, Japan and Canada. (Author).

The paper is a discussion of new information gathered from deep seismic soundings regarding the deep structure of the earth's crust in the USSR. It considers the thickness of the earth's crust, gravity anomalies and structure of the earth's crust. (Author).

Regional seismograms are dominated by the phases Pn, Pg, Sn, and Lg. More often Sn and Lg are used to infer the attenuation structure of the lithosphere. The seismic phase Sn is a high-frequency shear-wave (typically from 1 to 4 Hz and occasionally higher) that travels in the lithospheric mantle above the negative velocity gradient which usually marks the lithosphere-asthenosphere boundary. Sn has been reported out to distances of 35° (e. g. , MOLNAR and OLIVER, 1969; HUESTIS et aI. , 1973). Sn arrives as a high-frequency wave train lasting tens of seconds and up to 1 to 2 minutes. Sn velocities are typically 4. 7 km/s in stable continental and oceanic lithosphere (HUESTIS et al. , 1973) and as low as 4. 3 km/s (KADINSKY-CADE et al. , 1981) in more tectonically active regions. Lg is a complex short period guided wave consisting of high-frequency P and S energy which travels primarily in the earth's crust at frequencies typically between 0. 5 and 5 Hz. It has been modeled as higher-mode Love and Rayleigh waves as well as a sequence of multiply reflected post-critical S waves trapped in a crustal guide (BOUCHON, 1982; KENNETT, 1986; BOSTOCK and KENNETT, 1990). Lg has been observed not to propagate in oceanic or very thin continental crust (PRESS and EWING, 1952; SEARLE, 1975; ZHANG and LAY, 1995).