Modern Low-Magnitude Earthquake Swarms of the Gakkel Mid-Oceanic Ridge, Arctic Ocean

Abstract

Earthquakes at mid-ocean ridges (MOR) reflect the active magmatic and tectonic processes that form new oceanic crust. Active spreading processes of ultraslow ridges, with spreading rates of less than 20 mm/yr, are still poorly understood compared to the MOR in the Atlantic and Pacific oceans, with spreading rates of more than 25 mm/yr. Thanks to the installation of stationary seismic stations in the 21st century on the Arctic archipelagos of Franz Josef Land and Severnaya Zemlya, it became possible to record and study low-magnitude grouping earthquakes within the Gakkel Ridge, including swarm sequences of earthquakes. This article presents the first results of registration, location and study of swarm sequences of low-magnitude earthquakes within the Gakkel Ridge for the period from 2012 to 2022. It is shown that swarm sequences are recorded to a greater extent in the western volcanic and eastern volcanic segments of the ridge, while no such sequences were found within the central amagmatic segment. The structure formation of this part of the ridge is dominated by tectonic rather than magmatic and metamorphic processes. Two large swarm of low-magnitude earthquakes that occurred in the eastern volcanic segment of the ridge are considered in detail.