Compensatory Movements in the Source Zone of the 2023 High-Magnitude Earthquake Swarm in Herat Province, Afghanistan

Abstract—A source of a strong earthquake, as a rule, consists of subsources which are identified by waveform modeling. This modeling does not yield an unambiguous result. In this paper, we show an example when two significantly different focal mechanism solutions are presented for the same earthquake. In one solution, the subsources are characterized by similar faulting type, while in the other solution, the last subsource has an opposite mechanism. In (Vakarchuk et al., 2013), this discrepancy was interpreted as the realization of compensatory motion. The compensatory movements are detected not only in the subsources but also at the scale level of the source zone overall, where these movements manifest themselves in a certain regularity of the aftershock mechanisms discovered in the study of the 1970 Dagestan earthquake by Kuznetsova et al. (1976). In this paper, perhaps for the first time, compensatory movements are detected in a high-magnitude earthquake swarm lacking a pronounced main shock, which occurred in 2023 in Herat Province, Afghanistan. The results are supported by the set of the seismological and satellite interferometric data.