Slope instability and post-emplacement lava flow deformation revealed using interferometric synthetic aperture radar (InSAR) at Pacaya Volcano, Guatemala

Abstract:

Pacaya Volcano, Guatemala, is a dominantly basaltic complex that has been continually active since the 1960’s, with over 250 lava flows, intermittent strombolian activity, and ash and fumerolic plumes. Sometime between 0.6 and 1.6 ka B.P., the SW sector of the initial cone failed in a major edifice collapse. This event left a large arcuate scarp, within which the modern cone was constructed from historical times up to the present. Two collapses on the upper flanks of the cone near the main vent in 1962 and 2010, and uneven loading of lava flows on the SW flank are a cause for concern about the stability of this young edifice. For this study, ALOS PALSAR L-band Interferometric Synthetic Aperture Radar (InSAR) data was analyzed at Pacaya from February 2007 - February 2011. Interferograms reveal several applications of InSAR for understanding and monitoring activity at Pacaya, including: (1) lava cooling-related compaction during effusive activity, (2) inflation on the northern side of the cone prior to a large eruption on May 27^th, 2010, and (3) movement of the edifice to the SW during this large eruption, suggesting large-scale flank instability. With the implementation of InSAR technology at Pacaya in the future, we may be able to provide insights into the post-emplacement behavior of lava flows and shed light on edifice stability, leading to improved volcano hazard assessments.