FOCAL EARTHQUAKE MECHANISM: MODELING, PARAMETER IDENTIFICATION AND APPLICATION

Purpose. The purpose of the article is to determine focal mechanisms using a graphical method and the method of inverse waveforms with a limited number of stations, and to construct a fault plane for distributed sources. Design/methodology/approach. A matrix method was used for modelling seismic waves in a heterogeneous medium, which is represented as a horizontal layered elastic structure. The obtained expression for the displacement fields on the free surface on the layered half-space was used to determine the seismic moment tensor as a function of time by providing only direct P- and S-waves. We determined the slip for distributed sources using the methodology for a point source. So, to determining the components of the moment tensor, a source time function and a slip numerical method based on direct problem solution were used for inversion signals. Findings. We present the solution of the inverse problem to determine the focal mechanism using inverse waveforms for a limited number of stations and with graphic methods, as well as to determine the fault plane. Focal mechanism was defined by a graphic method and signal inversion for the event that took place near village Uhlya (24.10.2012, 03:13:40.50, ?0 = 48,1676°, ?0 = 23,6525°, h = 4,5 km, ML = 2,43), and also for the events that took place at Alberta, Canada (09.08.2014. 15:28:51.00, ?0 = 52,1646, ?0 = ?115,256, h = 4,9, ML = 3,8). Practical value/implications. We propose to apply graphic method to determine the focal mechanisms for events in the Carpathian region. We describe the method of inverse waveforms for a limited number of stations to determine focal mechanisms. The method for determining the fault plane using data from one or more stations is presented. The obtained focal mechanisms of local earthquakes and the parameters for distributed sources can be used to study stressed strained state of the mountain ranges in the regions with low seismic activity, which is important for Transcarpathian region.