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.

The principal hazard associated with future explosive eruptions of Alaska volcanoes is the generation of volcanic ash clouds which are explosively blasted high into the atmosphere and then drift away from the volcano with the wind. The fragments in the ash cloud (tephra) vary in size and the heavier particles fall near the source while finer particles travel downwind. This transported tephra will fall out of the cloud and accumulate on surfaces and structures, contaminate water sources, and infiltrate electronics and motors. The weight of significant accumulations may collapse structures and cause other damage. Chronic exposure to ash may be a significant public health hazard. This publication presents the frequency and location of tephra fall throughout Alaska and into the Yukon Territory of Canada, resulting from eruptions of Alaska volcanoes from the Pleistocene to the present. The tephra occurrence map facilitates better visualization of areas in Alaska with past occurrences of ashfall. The map is a useful indicator of regional potential ashfall hazards. All files can be downloaded free of charge from the DGGS website (http://doi.org/10.14509/30059).

High-resolution multichannel seismic reflection data were collected by the U.S. Geological Survey in July and August 2017 offshore southeast Alaska to expand data coverage along the Queen Charlotte Fault system.

High-resolution multichannel seismic reflection data were collected by the U.S. Geological Survey in July and August 2017 offshore southeast Alaska to expand data coverage along the Queen Charlotte Fault system.

Tephra fall (volcanic ash) studies are a key component to understanding the frequency and magnitude of volcanic eruptions and conducting volcano-hazard assessments. In addition, many interdisciplinary studies rely on tephra fall deposits as time-stratigraphic markers. Information on tephra deposits in Alaska has previously been dispersed amongst hundreds of publications that span numerous research disciplines. In order to streamline tephra occurrence data, information from these disparate publications have been compiled into one comprehensive geospatial dataset. Pleistocene, Holocene, and historical tephra deposit distribution information has been digitized for more than 120 published resources, including peer-reviewed articles, reports, and theses/dissertations. The dataset includes tephra fall distribution information pertaining to 39 eruptions from at least 19 volcanoes in Alaska. All files can be downloaded free of charge from the DGGS website (http://doi.org/10.14509/29847).

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.

This dataset contains digital data that were used for the creation of a geologic map shown in Figure 3 in USGS SIR 2017-5150; Postglacial Eruptive History and Geochemistry of Semisopochnoi Volcano, Western Aleutian Islands, Alaska by Coombs, M.L. and others. The map shows the generalized geology of the island and the locations of stations occupied during field work conducted in the summer of 2005. The data are based on mapping completed during the field work, high-resolution digital imagery, and geochemical and radiometric analyses of rock and soil samples.

This dataset consists of nine tables that include radiocarbon dates, Cesium-137 activity, grain size measurements, and scanning X-ray fluorescence element intensity counts.

Single-beam bathymetry data along with DGPS navigation data was collected as part of field activity L-10-81-AA in North Aleutians, Alaska from 08/16/1981 to 08/23/1981, The geophysical source was a Knudsen 12 kHz 320B/R echosounder. These data are reformatted from space-delimited ASCII text files located in the Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog at http://walrus.wr.usgs.gov/infobank/l/l1081aa/html/l-10-81-aa.bath.html into MGD77T format provided by the NOAA's National Geophysical Data Center(NGDC). The MGD77T format includes a header (documentation) file (.h77t) and a data file (.m77t). More information regarding this format can be found in the publication listed in the Cross_reference section of this metadata file.