DOI: https://doi.org/10.24028/gzh.0203-3100.v40i2.2018.128937

Isostasy and seismisity

S. V. Mishin, A. A. Panfilov, I. M. Khasanov

Abstract


A model of the Earth crust structure formed by gravitation of the planet has been considered. An important role in this structure is given to isostasy processes. Analysis of results of seismic exploration by reflected waves method allows to suggest that reflecting areas in the interior correspond to fissures and chambers in the material of rocks, which form the structures of the Earth crust. A suggestion has been made that weight loadings created by the planet gravitation are carried by the framing — bearing areas where geological bodies of different composition and form are contacting.  The weight of equal volumes of crust materials varies due to differences in the density of matter, presence of fissures and chambers.  Mountain structures are formed exactly due to such variations which determine the store of potential energy of masses of rocks. The presence of uplands near the valleys determines the gradients of potential energy and additional weight loadings in zones bordering mountain structures. As a result of lasting action of weight loadings bearing areas may be destroyed that leads to displacement of rock blocks; in this case potential energy is partly transformed into packets of mechanical impulse — seismic radiation characterizing the process of an earthquake.

As a model of seismic processes a shock with displacement of large blocks of rocks is considered. An earthquake is represented as a result of partial destruction of mountain structures. Results of model calculations of lower edges of mountain structures for two areas of the territory of Magadan region have been presented in the paper.


Keywords


geological bodies; isostatic equilibrium; earthquake; density; impulse

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