Ez-response as a monitor of a Baikal rift fault electrical resistivity: 3D modelling studies

O. V. Pankratov, A. V. Kuvshinov, D. B. Avdeev, V. S. Shneyer, I. L. Trofimov

Abstract


3D numerical studies have shown that the vertical voltage above the Baikal deep-water fault is detectable and that respective transfer functions, Ez-responses, are sensitive to the electrical resistivity changes of the fault, i.e.
these functions appear actually informative with respect to the resistivity «breath» of the fault. It means that if the fault resistivity changed, conventional electromagnetic instruments would be able to detect this fact by measurement
of the vertical electric field, Ez, or the vertical electric voltage just above the fault as well as horizontal magnetic field on the shore. Other electromagnetic field components (Ex, Ey, Hz) do not seem to be sensitive to the resistivity changes in such a thin fault (as wide as 500 m). On the other hand, such changes are thought to
be able to indicate a change of a stress state in the earthquake preparation zone. Besides, the vertical profile at the bottom of Lake Baikal is suitable for electromagnetic monitoring of the fault electrical resistivity changes.
Altogether, the vertical voltage above the deep-water fault might be one of earthquake precursors.

Keywords


Baikal rift zone;electromagnetic monitoring;transfer functions;resistivity changes ofthe fault

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References


DOI: https://doi.org/10.4401/ag-3267
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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X