Volcanic plume height correlated with magma-pressure change at Grímsvötn Volcano, Iceland

Abstract

Magma flow during volcanic eruptions causes surface deformation that can be used to constrain the location, geometry and internal pressure evolution of the underlying magmatic source 1 . The height of the volcanic plumes during explosive eruptions also varies with magma flow rate, in a nonlinear way 2,3 . In May 2011, an explosive eruption at Grímsvötn Volcano, Iceland, erupted about 0.27 km 3 denserock equivalent of basaltic magma in an eruption plume that was about 20 km high. Here we use Global Positioning System (GPS) and tilt data, measured before and during the eruption at Grímsvötn Volcano, to show that the rate of pressure change in an underlying magma chamber correlates with the height of the volcanic plume over the course of the eruption. We interpret ground deformation of the volcano, measured by geodesy, to result from a pressure drop within a magma chamber at about 1.7 km depth. We estimate the rate of magma discharge and the associated evolution of the plume height by differentiating the co-eruptive pressure drop with time. The time from the initiation of the pressure drop to the onset of the eruption was about 60 min, with about 25% of the total pressure change preceding the eruption. Near-real-time geodetic observations can thus be useful for both timely eruption warnings and for constraining the evolution of volcanic plumes.

Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption

“…This source contracts following the pressure difference DP related to the effusion rate Q(t) modelled as magmastatically driven Poiseuille flow 28 (equation (1)). The expected ground tilt induced by the measured effusion rate (Fig.…”

From magma ascent to ash generation: investigating volcanic conduit processes by integrating experiments, numerical modeling, and observations

“…Furthermore, strong assumptions on the rheological/mechanical parameters of the host rock (such as elasticity) are necessary to obtain information on pressurization. Correlations between surface deformation and flux measurements from plume height have been observed for the 2010 Grímsvötn eruption, Iceland [Hreinsdóttir et al 2014] and applied in Japan [Kozono et al 2014], and this may be useful in future eruptions. In addition, surface deformation and gravity measurements can be coupled to constrain the nature of the pressurization source [e.g., Bagnardi et al 2014, Carbone et al 2015, or the magma reservoir processes responsible for variations in volume within the plumbing system , Parker et al 2016.…”

Correlation between magma chamber deflation and eruption cloud height during the 2011 Shinmoe-dake eruptions

“…The relationship between magma chamber deflation and magma discharge processes (Figure 4) has also been investigated in the 2011 basaltic eruption of Grímsvötn Volcano by Hreinsdóttir et al (2014) on the basis of crustal deformation and cloud height measurements. They used the pressure change instead of the geodetic volume change to describe the deflation process of magma chamber.…”

“…Among the measurement devices, the borehole-type tiltmeters ) and the weather radar (Shimbori et al 2013) have been used to simultaneously observe the subsurface and surface phenomena, respectively; the tiltmeters detected deflation of a magma chamber caused by migration of magma to the surface during eruptive events, and the weather radar detected changes in the height of eruption cloud echo during column-forming eruptions. These kinds of measurements have been reported by Hreinsdóttir et al (2014), in which they showed the simultaneous measurements of crustal deformation and cloud height during the 2011 basaltic eruption of Grímsvötn Volcano in Iceland and indicated the usefulness of the measurements for constraining eruption dynamics.…”