This dataset consists of sample descriptions and radiocarbon age data from coastal environments on Montague Island, Alaska, analyzed at the National Ocean Sciences Accelerator Mass Spectrometry Facility.

This dataset consists of sample descriptions and radiocarbon age data from coastal environments on Montague Island, Alaska, analyzed at the National Ocean Sciences Accelerator Mass Spectrometry Facility.

On 16 July 2021, measurements were made of the volcanic gases emitted from Iliamna Volcano, Mount Douglas, Mount Martin, and Mount Mageik (Alaska, USA) from aboard a fixed-wing aircraft. Two zenith-facing differential optical absorption spectrometers were used to measure incident scattered solar ultraviolet radiation while traversing beneath the gas plumes on multiple occasions. These data were used to derive volcanic SO2 column densities and emission rates. In addition to the remote sensing payload, two in situ instruments were used to make measurements of trace gas concentrations while on flight paths through the volcanic plumes: a USGS multi-GAS (multiple Gas Analyzer System; Werner et al., 2017) analyzer for H2O-CO2-SO2-H2S, and an Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) instrument manufactured by Los Gatos Research, Inc., for H2O-HCl-HF. The CO2, SO2, and H2S sensors were calibrated five times in-flight at ambient pressures from 804-686 hPa (~1800-3000 m altitude) using standard gases stored in 25-liter capacity tedlar bags (CO2 = 448 ppm, SO2 = 2.1 ppm, H2S, = 2.0 ppm; all gases certified at ±2% accuracy). The H2O/CO2 analyzer’s baseline response was checked using small soda lime and anhydrite cartridges to remove H2O and CO2 from ambient air, and the sulfur sensors’ baselines were derived from their responses while sampling clean ambient air. In situ gas compositions were recorded at 1-second time resolution, while radiance spectra were acquired with variable integration times depending on illumination conditions and ranging from 1 to 3 seconds. Each spectrum and gas measurement was stamped with the GPS time and location. Each spectrum was saved in a separate ASCII file which includes 1024 radiances measured in the 265 - 403 nm spectral region and metadata associated with each acquisition. The in situ measurements are saved in a spreadsheet in the *.csv format.

On 16 July 2021, measurements were made of the volcanic gases emitted from Iliamna Volcano, Mount Douglas, Mount Martin, and Mount Mageik (Alaska, USA) from aboard a fixed-wing aircraft. Two zenith-facing differential optical absorption spectrometers were used to measure incident scattered solar ultraviolet radiation while traversing beneath the gas plumes on multiple occasions. These data were used to derive volcanic SO2 column densities and emission rates. In addition to the remote sensing payload, two in situ instruments were used to make measurements of trace gas concentrations while on flight paths through the volcanic plumes: a USGS multi-GAS (multiple Gas Analyzer System; Werner et al., 2017) analyzer for H2O-CO2-SO2-H2S, and an Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) instrument manufactured by Los Gatos Research, Inc., for H2O-HCl-HF. The CO2, SO2, and H2S sensors were calibrated five times in-flight at ambient pressures from 804-686 hPa (~1800-3000 m altitude) using standard gases stored in 25-liter capacity tedlar bags (CO2 = 448 ppm, SO2 = 2.1 ppm, H2S, = 2.0 ppm; all gases certified at ±2% accuracy). The H2O/CO2 analyzer’s baseline response was checked using small soda lime and anhydrite cartridges to remove H2O and CO2 from ambient air, and the sulfur sensors’ baselines were derived from their responses while sampling clean ambient air. In situ gas compositions were recorded at 1-second time resolution, while radiance spectra were acquired with variable integration times depending on illumination conditions and ranging from 1 to 3 seconds. Each spectrum and gas measurement was stamped with the GPS time and location. Each spectrum was saved in a separate ASCII file which includes 1024 radiances measured in the 265 - 403 nm spectral region and metadata associated with each acquisition. The in situ measurements are saved in a spreadsheet in the *.csv format.

Tephra samples and analyses from Cook Inlet source volcanoes and Anchor Point, Alaska, Raw Data File 2023-25, proivides samples and analyses collected from source volcanoes of the Cook Inlet region, Alaska, including Hayes Volcano, Mount Spurr, Redoubt Volcano, Iliamna Volcano, Augustine Volcano, Mount Douglas, Fourpeaked Mountain, and Kaguyak Crater. The report also includes tephra and soil samples and analyses from a stratigraphic section examined near Anchor Point, Alaska. These samples were collected over many years during geologic investigations of the eruptive histories for these source volcanoes, and in regional studies of eruption impacts, and are compiled here to support research characterizing the composition and impacts of these volcanoes on the Cook Inlet region. The analytical data tables associated with this report are provided in digital format as comma-separated value (CSV) files. They are available from the DGGS website: http://doi.org/10.14509/31090 and are archived in the Geologic Database of Information on Volcanoes in Alaska (GeoDIVA; Cameron and others, 2022, doi.org/10.14509/geodiva).

Davidof volcano samples and analyses, Raw Data File 2023-22, provides calculations and analytical results from samples collected in the western Aleutian Islands in 2021 by Alaska Volcano Observatory (AVO) geologists Hannah Dietterich and Matt Loewen. The primary target of this sampling was Davidof volcano, a partially submerged 5 km-diameter caldera located in the Rat Islands. Subaerial exposures include Davidof, Khvostof, Lopy, and Pyramid islands. The only prior published work on Davidof volcano was part of the U.S. Geological Survey's post World War II geologic reconnaissance of the Aleutian Islands (Nelson and others, 1959). Nelson and others (1959) only indicate two samples from Davidof volcano that were analyzed petrographically, but prior to this data release no quantitative data for Davidof volcano have been available. This report also includes samples collected during 2021 from the western shore of Little Sitkin Volcano, as well as new electron microprobe analyses from samples previously collected in 2005 and 2015 from Little Sitkin Volcano and 2015 from Segula Volcano. Data associated with this report are archived in the Geologic Database of Information on Volcanoes in Alaska (GeoDIVA; Cameron and others, 2022, doi.org/10.14509/geodiva. This report is released as a Raw Data File with an open end-user license. The data are available from the DGGS website: http://doi.org/10.14509/31084.

Alamagan Volcano is a Quaternary stratovolcano along the Mariana Arc, an active subduction zone in the western Pacific Ocean. Although primarily submerged, its peak reaches above sea level, with subaerially-exposed volcanic deposits dating back through the Holocene to the late Pleistocene. These feature data represent such deposits and other geologic features of Alamagan Volcano, describing its interpreted eruptive history.

Alamagan Volcano is a Quaternary stratovolcano along the Mariana Arc, an active subduction zone in the western Pacific Ocean. Although primarily submerged, its peak reaches above sea level, with subaerially-exposed volcanic deposits dating back through the Holocene to the late Pleistocene. These feature data represent such deposits and other geologic features of Alamagan Volcano, describing its interpreted eruptive history.

Alaska Volcano Observatory (AVO) geologists from the U.S. Geological Survey (USGS) and the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted fieldwork at Mount Veniaminof during field excursions between 2001 and 2016. The primary purpose of the fieldwork was geologic investigation of Veniaminof volcano to elucidate its eruptive history and understand its eruptive behavior. Teams of geologists focused on 1) edifice lava flows, 2) flowage deposits (lahars and pyroclastic flows), and 3) tephra-fall deposits. This Raw Data File comprises 61 whole-rock analyses of pumices from Holocene-age tephra deposits collected from 36 field stations on the flanks of Veniaminof volcano in 2001-2004, 2010, and 2016. All but four samples in this report were collected by geologists Kristi Wallace and Chris Waythomas during 1- to 2-week summer fieldwork campaigns. Thomas Miller and Charles Bacon contributed four pumice samples of a young dacite-composition tephra collected in 2001 and 2002. Mount Veniaminof is an ice-clad, basalt-to-dacite stratovolcano topped by an ice-filled caldera 10 km (about 6 mi) in diameter, located 775 km (482 mi) southwest of Anchorage on the Alaska Peninsula. With a volume of approximately 350 km3 (approximately 84 mi3) Veniaminof is one of the largest and most active volcanoes of the Aleutian Arc. Two Holocene caldera-forming eruptions are recorded in extensive pyroclastic-flow deposits around the volcano. Veniaminof has had at least 15 eruptions in the past 200 years, all from the approximately 300-m-high (about 984-ft-high) intracaldera cone and all largely basaltic-basaltic andesite composition, producing small lava flows and minor tephra deposits mostly confined to the caldera boundaries. The most recent explosive eruption was in 2018. Geochemical characterization of tephra deposits is most commonly executed by using glass-phase chemistry rather than whole-rock (bulk) geochemistry. The bulk composition of a tephra may change over fallout distance by eolian fractionation and therefore cannot be used to correlate tephra deposits over long distances. Whole-rock composition is commonly used to characterize juvenile material from flowage deposits (lahars and pyroclastic flows) and lavas. In order to readily compare (correlate) juvenile material from proximal tephra-fall deposits with other proximal deposits, tephra whole-rock analysis is required. This Raw Data File is focused only on whole-rock geochemical analyses of significant coarse-grained tephra deposits exposed on the flanks of Veniaminof volcano for use in correlating tephra deposits across the large volcanic edifice, and with proximal flowage deposits and edifice lava flows. Results of glass geochemistry of Veniaminof tephra and all other whole-rock analyses of samples collected is part of an ongoing study and not included in this report. Files can also be downloaded from the DGGS website (http://doi.org/10.14509/30578) and is also available in .html and .csv from the AVO Geochemical Database (https://avo.alaska.edu/geochem). Sample descriptions, locations, and sample types are included in the analytical data table. Samples collected during this project, including hand sample material, remaining powder from these whole-rock analyses, and partially crushed sample remains are stored at the Alaska Geologic Materials Center or at the USGS Alaska Tephra Laboratory in Anchorage.