The seismo-mechanical coupling of ring-fault earthquakes accompanying the 2014-2015 caldera collapse at Bárðarbunga volcano, Iceland

Abstract:

The 2014-2015 collapse of the Bárðarbunga caldera was accompanied by a notable seismic sequence. We determine full moment tensors and relative centroid locations for 77 M > 5 earthquakes, revealing that they cluster beneath the northern and southern caldera rims and can be interpreted by frictional controlled sliding events at segments of the caldera ring fault and additional sub-vertical CLVD sources below, possibly related to the response of the magma reservoir feeding the Bardabunga fissure eruption.

In this presentation we analyze the friction controlled occurrence of rim fault events induced by a continuous depletion of the magmatic reservoir. Earthquakes in the northern cluster occur at deeper levels than in the southern cluster. The earthquake occurrence rate and their temporal evolution differs in the northern and southern clusters.

We analyze the temporal-spatial evolution of both clusters in combination with mechanical collapse models and time and size predictive statistical earthquakes models.