SEPTEMBER 4, 2018 KATAV-IVANOVSK EARTHQUAKE with ML=5.4, mb=5.5, I0=6.4

Abstract

The instrumental and macroseismic data on the earthquake of September 4, 2018 at 22h58m19s UTC, ML=5.4, I0=6.4±0.3 near the city of Katav-Ivanovsk in the Chelyabinsk region (South Urals) are presented. This event with ML=5.4 mb=5.5 became the strongest instrumentally recorded earthquake in the Urals and had the highest macroseismic effect among the Russian earthquakes in 2018 (I0=6.4±0.3). For the first time in the practice of processing macroseismic data in the Urals, the Seismic Intensity Scale 2017 (GOST R 57546-2017) was used. For the first time for natural earthquakes in the Urals, an aftershock process was recorded, the active stage of which lasted about 11 months, while many aftershocks had a significant macroseismic effect. Taking into account the spatial orientation of the aftershock cloud, the focal mechanism solution was confirmed and the tectonic position of the source was substantiated.