Multichannel Seismic Profiling, Gas Hydrates and the Numerical Simulation of the Mud Volcanoes Formation Conditions in Lake Baikal

Golmshtok A. Ya.

It is shown, that such a phenomenon as the undulating bottom simulating reflector, which was revealed in 1992 in Lake Baikal, could be explained by the presence here of the thermal convection cell. However, the hypothesis of the tectonic origin of this phenomenon is more probable. The numerical modelling of the thermohydrodynamic regime evolution of the «Malenkij» mud volcano in Lake Baikal is carried out. It is based on solving of the problem of methane hydrate phase transition in porous sediments. The choice of an adequate model and its parameters is carried out by analyzing the data of the multichannel seismic profiling. The large inflow of water in the volcan channel might be explained by the action of shear faults. Estimations of the over-hydrostatic pressure of the methane-gas, generated by dissociation of methane hydrates, show that this pressure is low. It can not be the cause of the breaking of near-bottom sediments and subsequent downward flow of lake water along formed fractures. The method of simultaneous numerical evaluation both the maximum velocity of the water inflow into the channel and the age of the mud volcanoes, formed in the decomposition conditions of gas hydrates, is proposed. Using this method it was found, in particular, that the mud volcano «Malenkij» was formed not earlier than 6.4 and not later than 5 thousand years ago at the maximum velocity of the water inflow through the channel’s base equal 7.7±1.4 cm/yr.

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