DOI: 10.5066/p9veffrx
title: Digital elevation models and orthoimagery from the 2018 eruption of Veniaminof, Alaska

description: Aerial photography surveys during and after the 2018 eruption of Veniaminof Volcano, Alaska were conducted to track the evolution of the lava flow field, active volcanic vent, and glacial ice loss from the eruption. Imagery from two surveys was processed with structure-from-motion (SfM) photogrammetric methods to derive the digital elevation models (DEMs) and orthophotos in this data release. The datasets cover the active volcanic cone and intracaldera ice cap, which both show significant topographic and groundcover change between surveys, and relative to previous topographic reference data, due to the 2018 eruption and variable snow and ice cover. A syn-eruption survey on September 26, 2018 was conducted by the U.S. Fish and Wildlife Service from a Found Bush Hawk fixed-wing aircraft with on-board Trimble R7 GNSS receiver and a nadir-mounted Nikon 850 camera and Nikon AF-S NIKKOR 24mm f/1.4G ED Lens. The flight was conducted at an altitude of 6000 feet above ground level with 80% overlap and 50% sidelap from adjacent flight lines. Survey coverage was restricted by volcanic emissions during the flight. The camera was triggered using an Aero Scientific trigger system at predetermined GPS locations. The GPS time of the camera shutter event was recorded by the Trimble R7 receiver in the GNSS log file by a connection to the camera hot shoe. Precise camera positions were calculated by processing the GNSS log file using Waypoint GrafNav software by NovAtel. The precise camera position and images were processed with Agisoft Metashape using SfM methods to produce a high-resolution orthophoto (0.3 m cellsize) and DEM (0.58 m cellsize). Root mean square error of 2.3 m estimated from control points on the USGS 2018 IfSAR DEM. A helicopter survey of the post-eruption flow field was conducted by the U.S. Geological Survey on June 29, 2019, taking oblique aerial photographs with a GPS-enabled Canon 6D Mark II camera. The Bell 206 Egli Air Haul helicopter flew orbits around the target region at 500?-2000 ft above ground level to produce &gt;70% image overlap. The images were processed with the on-board camera GPS positions in Agisoft Metashape using SfM methods to produce a high-resolution orthophoto and DEM. Because of the lack of high-precision camera locations during the post-eruption survey, the June 2019 DEM was georeferenced to control points on the September 2018 model. The orthophoto and DEM have a horizontal resolution of 0.25 , with a root mean square error of 2.7 m within the eruption area estimated from control points on the USGS 2018 IfSAR DEM. These data are valuable for assessing the volume and morphology of the volcanic eruption products and their impact on the ice surface. Absolute data accuracy is limited by the inaccessibility and perpetual change of the active volcanic and glacial landscape, but these data offer a means of quantifying and studying the dynamic processes of glaciovolcanism. From limited control points in unchanged regions between the two structure-from-motion DEMs, the uncertainty in elevation change values is 1.7 m. Volcanic ash and gas emission produce local data gaps and spurious values near the active vent in all datasets. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. IfSAR DEM citation U.S. Geological Survey, 20191210, USGS Alaska 5 Meter AK IFSAR Eastern Aleutians Lot3 C358 2018 DEM n5600w15930P: U.S. Geological Survey https://www.sciencebase.gov/catalog/item/5e267089e4b014c85306f7dc