Analysis of Deformation Data at Grímsvötn (Iceland) Reveal Viscoelastic and Cyclic Magma Chamber Dynamics

Abstract

Volcanic eruptions are quite unpredictable and pose a great hazard to humans and society. The most efficient way to mitigate this hazard is through improved understanding of volcanic systems. This can be done through numerical modeling of the chamber dynamics and combining this with data analysis. In this thesis I present a new method that models viscoelastic magma chamber deformation. I apply this to the Grímsvötn volcano in Iceland. The Grímsvötn deformation data reveals an eleven year periodicity. This period is also present in other deformation data from Iceland, as well as world wide. Further analysis suggests that this periodicity is strongest near hotspot volcanoes and also strongly correlated with the solar cycle. After removal of this periodicity, as well as other periodicities, I performe viscoelastic inversion to the Grímsvötn data. I find a relaxation time of 166 days, and estimate the chamber to have a mush content of 16-25% with a viscosity of about 10^17 Pa-s. Further modeling, more data and subsequent data analysis is required to fully understand the processes at hand.