Elastic modeling of the Pacaya volcanic complex: a 2009-2015 campaign-GPS deformation history

Abstract:

Pacaya volcano, in Guatemala, is a basaltic stratovolcano that has been consistently active since 1961. It is known to produce both effusive and explosive eruptions and the erupted material over the last 50+ years has been asymmetrically deposited within an ancestral collapse scarp on the western flanks. This continuous activity and unbalanced edifice presents considerable risk to nearby communities and offers ideal conditions for geodetic applications to monitoring, the study of magmatic systems, and volcano dynamics. Since 2009 periodic campaigns have been conducted to collect GPS data from a six-benchmark network surrounding the volcano. These data span both a 2010, VEI 3 and 2014 VEI 2 explosive eruptions. Initial analysis show total horizontal and vertical displacements up to 40 cm throughout the time series. This research investigates the deformation associated with these eruptive events and inter-eruptive phases in an attempt to improve our understanding of the magma distribution at depth and its influence on the volcanic edifice deformation. Modeling a simplistic point pressure source in a homogeneous half space suggests a fairly shallow deformation source which seems to agree with a hypothesized shallow magma reservoir and vertical, NW-SE trending dike that may influence vent location and edifice stability. Given Pacaya’s eruptive and collapse history, continuous monitoring of deformation using GPS and a better understanding of the magmatic plumbing system is essential for improved risk assessment.Pacaya volcano, in Guatemala, is a basaltic stratovolcano that has been consistently active since 1961. It is known to produce both effusive and explosive eruptions and the erupted material over the last 50+ years has been asymmetrically deposited within an ancestral collapse scarp on the western flanks. This continuous activity and unbalanced edifice presents considerable risk to nearby communities and offers ideal conditions for geodetic applications to monitoring, the study of magmatic systems, and volcano dynamics. Since 2009 periodic campaigns have been conducted to collect GPS data from a six-benchmark network surrounding the volcano. These data span both a 2010, VEI 3 and 2014 VEI 2 explosive eruptions. Initial analysis show total horizontal and vertical displacements up to 40 cm throughout the time series. This research investigates the deformation associated with these eruptive events and inter-eruptive phases in an attempt to improve our understanding of the magma distribution at depth and its influence on the volcanic edifice deformation. Modeling a simplistic point pressure source in a homogeneous half space suggests a fairly shallow deformation source which seems to agree with a hypothesized shallow magma reservoir and vertical, NW-SE trending dike that may influence vent location and edifice stability. Given Pacaya’s eruptive and collapse history, continuous monitoring of deformation using GPS and a better understanding of the magmatic plumbing system is essential for improved risk assessment.