The past, present, and future of Laguna del Maule volcanic field, southern Andes: insights from high-resolution topographic data

Abstract:

We present the first high-resolution topographic model of the Laguna del Maule (LdM) volcanic field. Post-glacial volcanism comprises >50 km³ of lava flows, domes, monogenetic and composite cones and voluminous rhyolitic pyroclastic flow and fall deposits. The ~400 km² central lake basin straddles the Chile-Argentina border. In January 2016 and April 2017, oblique photogrammetry surveys of the LdM lake basin, Maule Valley, and Troncoso Valley were conducted via helicopter. A network of ~50 ground control points was deployed using campaign GPS and photo targets. Approximately 10,000 digital photos were acquired during the helicopter surveys and were processed using a USGS super cluster network to create a 0.5 m resolution digital elevation model (DEM) of the lake basin. We supplemented the 0.5 m DEM with additional high-resolution (1 m) DEMs derived from along-track stereo satellite imagery collected in-sync with our oblique photogrammetry surveys. The new high-resolution DEM allows us to improve estimates of erupted volumes of flows and domes, precisely define and map an early Holocene lake high-stand paleo-shoreline, calculate the volume of the paleo-lake and model potential lahar inundation down the Maule and Barrancas river valleys using improved estimates of the current lake volume. The unprecedented resolution of the DEM facilitates identification of pre-and-post glacial units as well as those erupted following a paleo-lake outburst flood and can guide future instrument deployments, hazardous flow modeling, and the mapping of geologic structures and Holocene deformation. In addition, we investigated the use of multi-temporal DEMs and sub-pixel correlation routines using additional optical satellite imagery (along-track stereo and single scenes) collected between 2007-2017 to study deformation within the volcanic field, most notably, the uplift signal of >20 cm/year that has been centered in the southwestern portion of the lake basin since 2007.