The 21 March 2022 Mw 5.1 Tampen Spur Earthquake, North Sea: Location, Moment Tensor, and Context

Abstract

ABSTRACT The 21 March 2022 Mw 5.1 Tampen Spur earthquake is the largest event in the North Sea over the last 33 yr. The earthquake was recorded by a 10,708 sensors permanent reservoir monitoring system (PRM) deployed at the Snorre field only a few kilometers away from the epicenter. The event was also recorded on regional networks, as well as at teleseismic distances. Here, we take advantage of this large number of observations to relocate this seismic event, estimate a moment tensor, and refine the depth of the earthquake. The different data sets and location methods yield similar locations, suggesting a well-constrained earthquake location with a depth of 22 ± 5 km. Furthermore, a moment tensor is estimated, which indicates a thrust fault mechanism. Deep crustal earthquakes (>20 km) have been documented within several continental rifts, for example, in Basin and Range in the United States and in northern Germany. Studying deep intraplate earthquakes such as the event observed here can offer insights into the rheology and structures in the deeper portions of the crust. This thrust earthquake implies the reactivation of an older fault in the lower crust consistent with the ridge-push forces from the mid-Atlantic ridge. Such brittle failure at depth indicates a lower crust with little to no fluids present at this depth within the Tampen Spur region.