GEOPHYSICAL RESEARCH, 2019, vol. 20, no. 4, pp. 65-93. https://doi.org/10.21455/gr2019.4-5
UDC 550.34
Abstract References Full text (in Russian)
ON THE STRESS FIELD EVALUATION OF THE COMMANDER BLOCK OF THE ALEUTIAN ISLAND ARC BASED ON THE KINEMATIC PARAMETER VP/VS DATA AND ON THE FOCAL EARTHQUAKE MECHANISMS
L.B. Slavina, M.S. Kuchai
Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
Abstract. The kinematic parameter VP/VS was used to study the stress field dynamics of the geological and geophysical environment of the Komandorsky block of the Aleutian island arc. Real-time seismic mode observations of stationary seismic digital network KF GS RAS are used.
It has been established that according to the nature of distribution and grouping in space and depth of the anomalous values of the VP/VS parameter, it is possible to distinguish the characteristic features of the stress field for tectonic structures and faults. Assess the nature and type of offsets on them. The stress field in kinematics indicates the shear nature of dislocations along the Bering Fault, one of the most seismically active western segment of the Commander block. For the northeast plane of the fault, plunging under the Commander depression, characterized by lower values of VP/VS. That may indicate the dilatancy nature of the process, the process of stretching in the stress field.
The estimates of the stress field by the VP/VS parameter are compared with the mechanisms of the foci of strong earthquakes that have occurred in this region in recent years.
The sections constructed from the field of VP/VS values are compared with the acoustic sections obtained during offshore work using the continuous seismic profiling method (NSP) during the International Geophysical Year.
Considered the question of the existence or absence of a subduction zone, i.e. diving Pacific plate under the Commander block of the Aleutian island arc.
The results indicate that it is possible to use the method of observation of the VP/VS parameter in the operational evaluation of the stress field in the future, according to regional seismic activity.
Keywords: earthquake, seismic wave velocity, VP/VS value, subduction zone, the Commander block of the Aleutian island arc.
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