The Uglovoye Podnyatiye Earthquake on December 20, 2018 (Mw = 7.3) in the Junction Zone between Kamchatka and Aleutian Oceanic Trenches

Abstract

The paper presents the first results of integrated research of the strong seismic event (Uglovoye Podnyatiye earthquake (UPE) with a magnitude of Mw=7.3) that occurred on December 20, 2018 in the junction zone between the Kuril-Kamchatka and Aleutian island arcs. The authors has provided macroseismic information about the UPE, calculated peak ground accelerations and the seismic moment tensor, and described briefly the forshock and aftershock processes, as well as summarized data on earthquake precursors. UPE was reported to be felt at distances of up to 500 km. The maximum shaking was recorded as I = 5–6 at an epicentral distance of Δ~90 km on Bering Island, where the maximum instrumental acceleration of ~60 cm/s2 was recorded. It is shown that foreshocks remote in time occurred 2 years prior to the UPE. The distinctive grouping of the aftershocks in three spatially isolated clusters characterized by different parameters of the seismicity time course is related to the long and intense aftershock process of the UPE. The strongest aftershock had magnitude ML=6.6, another 25 events corresponded to ML≥5.0. UPE was preceded by precursor anomalies in the parameters of geophysical fields and the seismic process. The authors estimated the size of the UPE rupture, the depth of the equivalent source, the magnitude of the focal slip, and the duration of the rupture. The seismic moment tensor UPE has a large non-dipole component.

Keywords

• earthquake
• aftershock
• foreshock
• precursor
• earthquake mechanism
• tsunami
• kamchatka