Variations of apparent electric rock resistivity during the Kizilyurt earthquake of 1999 in Dagestan
Category: 14-2
UDC 550.837: 550.343
Sh.G. Idarmachev(1), M.M. Aliev(2)
(1) Institute of Geology, Dagestan Scientific Center, Russian Academy of Sciences,
Makhachkala, Russia
(2) Institute for Geothermal Problems of the Dagestan Scientific Center,
Russian Academy of Sciences,
Makhachkala, Russia
Abstract
We consider the dipole electric sounding data on the Khadum dome during the Kizilyurt earthquake, which occurred January 31, 1999. Before the major thrusts in the magnitude range of 5.7–4.6 an anomalous 85-20% decrease of the apparent resistivity of the rock mass, associated with the preparation for ruptures in the crust, was detected. Spatial distribution of epicenters of the Kizilyurt earthquake and its aftershocks confirms their connection to the earthquake of May 14, 1970. It is suggested that variations in apparent resistivity resulted from rock extension before the earthquake, which creates an electric screen between the supply and receiving dipoles of the sounding system. A laboratory simulation, which confirms the process of screening of the field, was conducted.
Keywords: earthquake, dipole sounding, aftershock, apparent electric resistance.
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