Rapid transport of ash and sulfate from the 2011 Puyehue‐Cordón Caulle (Chile) eruption to West Antarctica

Abstract

AbstractThe Volcanic Explosivity Index 5 eruption of the Puyehue‐Cordón Caulle volcanic complex (PCC) in central Chile, which began 4 June 2011, provides a rare opportunity to assess the rapid transport and deposition of sulfate and ash from a midlatitude volcano to the Antarctic ice sheet. We present sulfate, microparticle concentrations of fine‐grained (~5 μm diameter) tephra, and major oxide geochemistry, which document the depositional sequence of volcanic products from the PCC eruption in West Antarctic snow and shallow firn. From the depositional phasing and duration of ash and sulfate peaks, we infer that transport occurred primarily through the troposphere but that ash and sulfate transport were decoupled. We use Hybrid Single‐Particle Lagrangian Integrated Trajectory back trajectory modeling to assess atmospheric circulation conditions in the weeks following the eruption and find that conditions favored southward air parcel transport during 6–14 June and 4–18 July 2011. We suggest that two discrete pulses of cryptotephra deposition relate to these intervals, and as such, constrain the sulfate transport and deposition lifespan to the ~2–3 weeks following the eruption. Finally, we compare PCC depositional patterns to those of prominent low‐ and high‐latitude eruptions in order to improve multiparameter‐based efforts to identify “unknown source” eruptions in the ice core record. Our observations suggest that midlatitude eruptions such as PCC can be distinguished from explosive tropical eruptions by differences in ash/sulfate phasing and in the duration of sulfate deposition, and from high‐latitude eruptions by differences in particle size distribution and in cryptotephra geochemical composition.