The symposium discussed the characteristics of waves, the nature of seismic boundaries, and the structural variety of the Earth's crust, as well as results obtained by comparing seismic and graviuretric data.
Several papers were devoted to studies of wave patterns recorded during earthquakes and powerful explosions. Papers on this subject were delivered by S.I. Masarskii, N. I. Bulin, E. M. Butovskaya, and D. D. Sultanov.
3. Some of the papers dwelt on the shortcomings of the existing apparatus and ways to eliminate them. Their authors complained about the limited application of the most modern achievements of radioelectronics, etc.
The principal speakers on this subject were A.N. Mozzhenko and S. I. Ivanov.
Yu. P. Neprochnov spoke on the use of radio buoys in maritime work; V. S. Voyutskii reported on the use of accumulation methods for improving the effective sensitivity in working on land. Observation methods and techniques were discussed by M. A. Zaionchkovskii.
Several papers were concerned with further development of DSS and seismic prospecting in general, including the nature of waves, the nature of seismic boundaries, the intensity of waves and their frequency spectrum as functions of the weight of charge, low-frequency seismics, the use of spectroscopy, etc. These contributions were made by A. M. Epinat'eva, G.N. Pariiskaya, G.G. Mikhota, Yu. I. Vasil'ev, L. L. Khudzhinskii, and others.
The symposium adopted a resolution which enumerated several dis advantages of DSS, and also suggested ways to eliminate them, and to further improve and develop this method, as well as conditions for its most efficient use in conjunction with other geophysical methods.
The following is a brief summary of the principal recommendations by the symposium: 1. Continuation and expansion of work on DSS for investigating the inner structure of the crust, primarily in regions of a basically different geological structure.
2. Organizing the planning and coordination of DSS work in conjunction with other geophysical methods for investigating the structure of the Earth's crust, initially with the aid of gravimetric and aeromagnetic methods. For this purpose an interdepartmental coordination commission for deep geophysical investigations will be established.
3. Special experimental research methods for improving DSS on sea and on land.
4. Continuation and expansion of research on dynamic wave character
istics, devising methods for the interpretation of refracted and deep reflected waves.
5. Designing of new apparatus based on the most modern achievements of radioelectronics and instrumentation.
6. Generalization of all DSS data obtained in the USSR over the last 10 years. Not only is this in itself of scientific interest, but it is also necessary for devising a reliable and uniform interpretation method and an efficient complex of geophysical methods for investigating the Earth's crust and the outer portion of the mantle.
7. Expansion of investigations into the physicomechanical properties of rocks under thermodynamic conditions corresponding to those prevailing in the Earth's crust.
8. Improvement of methods for studying the outer portion of the Earth's mantle. Recommendations to Soviet seismologists for more active work on the seismological methods used in studies of the Earth's crust and the and the outer mantle. Utilization of large-scale industrial explosions, performing the observations with DSS and seismological apparatus.
A plan is being devised in the USSR for extensive work on infra-deep drilling for the direct study of rocks in the Earth's crust and the outer mantle under significantly different structural conditions. Deep boreholes are planned as follows: 1) through sedimentary layers into granite; 2) through sedimentary layers into basalt; 3) through granite into basalt; 4) through basalt into Moho, i. e., into the mantle rocks.
It is hoped that the implementation of this plan, besides developing borehole observation techniques, will yield highly valuable information on the composition and nature of the crustal strata and the outer mantle. It will also make possible the most comprehensive use of the inherent possibilities of DSS and the entire complex of geophysical and geological methods for the investigation of the Earth's crust and the outer mantle, leading to a better substantial interpretation of the data. In this manner conditions will be created for a detailed and systematic study of the structure of the Earth's crust on the territory of the USSR, where a great variety of structure and composition can be expected. It will then be possible to solve some of the most important problems of modern Earth science.