Evolution of aftershock sequence of December 20, 2018 strong earthquake (Mw = 7.3) and its reflection in Vp/Vs-parameter field

Abstract

The paper presents the results of calculations, as well as further analysis of the kinematical parameter Vp/Vs in the source area of the strong earthquake (Mw = 7.3), which occurred on December 20, 2018 at the junction of the Kurile-Kamchatka and Aleutian trenches. Calculations of the Vp/Vs field based on the results of processing the parameters of moderate and weak earthquakes (Mw ≤ 6.5) in the earthquake source area and its surroundings, registered by the system of seismic observations of the Kamchatka branch of Federal Research Center « Geophysical Survey of RAS» in the period from 2009 to 15.06.2019. The results of the analysis of the Vp/Vs field and its comparison with the mechanisms of strong events in the vicinity of the source area of the studied earthquake lead us to the conclusion that the kinematic parameter Vp/Vs characterizes the elastic and strength properties of the geophysical environment, and also reflects the nature and changes in the stress field. The paper discusses also the probable effect of deformation regime on the type and form of distribution of the Vp/Vs parameter. This may be of particular importance for the development of methods of earthquake prediction and diagnosis of the environment.

Keywords

• kamchatka
• earthquake of corner rise
• seismicity
• aftershock
• vp/vs parameter