September 4, 2018, Katav-Ivanovsk Earthquake with ML = 5.4, mb = 5.5, I0 = 6.4

The instrumental and macroseismic data on the earthquake of September 4, 2018 at 22:58:1 UTC, ML = 5.4, I0 = 6.4 ± 0.3, near the city of Katav-Ivanovsk in Chelyabinsk oblast (Southern Urals) are presented. This event with ML = 5.4 and 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.