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. The modeling does not yield an unambiguous result. In this paper, we present an example when two significantly different focal mechanism solutions are published for the same earthquake: in one solution, the subsources are characterized by a similar type of faulting, while in the other solution, the last subsource has an opposite mechanism. In (Vakarchuk et al., 2013), this discrepancy was interpreted by the realization of a compensatory motion. The compensatory movements are detected not only in the subsources but also at the scale level of the entire source zone, which manifest itself 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 without a pronounced main shock, which occurred in 2023 in Herat Province, Afghanistan. The results are supported by a series of seismological and satellite interferometric data.