Perm Journal of Petroleum and Mining Engineering (Dec 2017)
Connections between intermediate & shallow-focus earthquakes and tectonic faults based on data of CDP seismic survey method
Abstract
The territory of Azerbaijan located in the central part of the Mediterranean mobile belt is characterized by high seismicity, mud volcanism, widespread slumps and contrast character of modern vertical and horizontal movements occurring in the sedimentary part of the geological section. The paper contains results of studies of the features of the connection of earthquakes and tectonic movements that cover the Mesozoic and Cenozoic intervals of the geological section. The work is carried out with a complex interpretation of data by the method of the common depth point (CDP) of seismic survey; well logging; vertical seismic profiling (VSP) performed on the study area and its periphery; observations of seismic for the period from 2003 to 2016. A comprehensive interpretation of the data allow to construct several seismogeological profiles in a direction perpendicular to the axis of the Caucasian mountain structures. Several profiles of a similar direction (SW–NE) were compiled along the Caspian Sea as well. The geological section is split into stratigraphic and lithologic-facies intervals based on CDP seismic data using VSP and well logging data. Analysis of dynamic and kinematic parameters of the seismic wave field recorded on the area of interest showed that a tectonic process began in the Mesozoic (possibly Paleozoic) period, continued to the end of the Cretaceous, somewhat decreased (unloaded) at the beginning of the Cenozoic and then continued in the Quaternary period. The seismic activity of the region confirms that the process continues nowadays. Based on the results of a joint interpretation of seismology and CDP seismic survey data it was established that shallow-focus earthquakes in the foothill regions of Azerbaijan occurred and occur under the influence of global tectonic processes that create a prolonged geodynamic tension in the upper part (to the depth of 12 km) of the sedimentary complex of deposits. Joint interpretation of CDP seismic survey data and seismology indicates the presence of a collision zone in the area of the junction of the South Caspian depression and Absheron-Pribalkhanskiy threshold, interpreted by some researchers as a subduction zone. The analysis of geological and geophysical data accumulated during the period from 1985 to 2015 tells about the need to revise the tectonic map of the oil and gas bearing regions of the republic and its connection with the seismic map of the territory.
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