Altai earthquake (2003) fault zone velocity structure - case study

Abstract

This paper presents the results of seismic surveys in the epicentral zone of the Alaty earthquake (2003), conducted in the summer of 2021. The object of research was a fractured zone, which on the surface manifests itself as a rupture of the earth's surface with a width of 3-5, a depth of up to 1 and a length of about 200 meters. The main objective of the 2021 research was to study changes in the structure of the velocity section in the rupture zone, presumably associated with the degradation of the permafrost. As a result of processing records of refracted waves, a seismotomographic model for P-waves was obtained, and a seismic boundary was identified by the GRM method. As a result of processing surface wave recordings by MASW, one-dimensional S-wave sections were obtained for the left and right parts of the section. Interpretation of the results showed the presence of a huge unfrozen zone with a thickness of about 30 meters, which indicates an active process of degradation of the permafrost in this area.