This dataset comprises the locations of volcanoes and volcanic centers in Alaska.

Recently active volcanoes of Alaska, Miscellaneous Publication 133 v. 6, lists the historically active volcanoes of Alaska and the year of the last major eruptive event. The volcanoes listed meet at least one of the following criteria since 1700 CE: 1) Documented, unquestioned eruption OR 2) A strongly suspected eruption, often an eruption documented in a historical account with very little information. Current geologic knowledge must not contradict the eruption account, OR 3) Persistent (usually on the order of decades, but certainly longer than several months) fumaroles, with temperatures (where measured) within approximately 10 degrees C of the boiling point, OR 4) Significant, measured, volcanic-related, non-eruptive deformation, OR 5) Documented earthquake swarm with strongly suspected volcanic cause. This data is released as a Miscellaneous Publication with an open end-user license. The data are available from the DGGS website: http://doi.org/10.14509/31086.

The geologic map database in this data release is a reproduction of the U.S. Geological Survey Professional Paper 1762: Volcanic Processes and Geology of Augustine Volcano, Alaska, Waitt and Begét (2009). The database consists of a geologic map and one structural cross section that conform to the National Geologic Map Schema (GeMS). These data supersede USGS Data Series 677: Database for Volcanic Processes and Geology of Augustine Volcano, Alaska, McIntire and others, 2012. Augustine Island (volcano) in lower Cook Inlet, Alaska, has erupted repeatedly in late-Holocene and historical times. Eruptions typically beget high-energy volcanic processes. Most notable are bouldery debris avalanches containing immense angular clasts shed from summit domes. Coarse deposits of these avalanches form much of Augustine's lower flanks. This geologic map, at 1:25,000, show the distribution and relations of volcanic units at Augustine Volcano. This database does not reproduce all elements of the original publication. Omissions include the chart and figures showing the measured sections on Augustine Island and Shuyak Island, Alaska, and the chart and diagram for the correlation of map units. Versions of these data are provided in open-access formats that are compatible with a broad range of geospatial applications. The open-access data is derived from the file geodatabase using a python script downloadable at https://github.com/doi-usgs/gems-tools-pro. Vector data are provided as shapefiles and tabular data are provided in *.txt and *.csv formats. Any shapefiles derived from the geodatabase may have prefixes of GM_[filename] and CS_[filename] indicating features are part of the geologic map or a structural cross section, respectively. Attribute table field names may be automatically abbreviated or shortened to 10 characters to conform with the shapefile format. The annotation feature class (a native format of the Esri file geodatabase) for the structural cross section is omitted because there is no equivalent open file type. Symbology layer files (*.lyrx) are provided for symbolizing the map using the intended symbols, lines, fills and patterns and a copy of the database. We recommend Esri software users set the display reference scale between 1:10,000 and 1:24,000 for optimal display of symbology, and enable the Maplex labeling engine for optimal display of labels. Users of this database are highly encouraged to cross reference this database with the original publication.

Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. The eruption was predominantly phreatomagmatic, producing fine-grained tephra that covered most of northeastern Umnak Island. The eruption had a maximum Volcanic Explosivity Index (VEI) of 4, with eruption column heights up to 16 km during the opening phase. Several craters and a master tuff cone formed in the caldera as a result of phreatomagmatic explosions and accumulated tephra-fall and surge deposits. Ascending magma continuously interacted with an extensive shallow groundwater table in the caldera, resulting in the phreatomagmatic character of the eruption. Syneruptive explosion and collapse processes enlarged a pre-existing lake, created a second, entirely new lake, and formed new, deep craters. A field of ephemeral collapse pits and collapse escarpments formed where rapid groundwater withdrawal removed material from beneath capping lava flows. This was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977. This digital data release provides GIS files of field station locations and various geographic features described in the accompanying report.

This data lists the historically active volcanoes of Alaska, their location in latitude/longitude decimal degrees, and the year of the last major eruptive event. The 52 volcanoes listed meet at least one of the following criteria since 1700 CE: (1) documented, unquestioned eruption, or (2) a strongly suspected eruption, often an eruption documented in the historical account with very little information (current geologic knowledge must not contradict the eruption account), or (3) persistent (usually on the order of decades, but certainly longer than several months) fumaroles, with temperatures (where measured) within ~10°C of the boiling point, or (4) significant, measured, volcanic-related, non-eruptive deformation, (5) documented earthquake swarm with strongly suspected volcanic cause.For the purposes of this dataset a major eruptive event is considered to be one in which juvenile lava erupt as a lava flow or dome or as an explosive column reaching an altitude of several thousand meters above the vent. This data is represented cartographically in Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 133 (Schaefer, J.R., Cameron, C.E., and Nye, C.J., 2009) where the volcano locations are displayed on a grayscale digital shaded relief image of Alaska with a background image of colorized bathymetry.

Report of Investigation 2017-10, Geologic map of Mount Chiginagak volcano, Alaska, provides 1:25,000 geologic mapping of the Chiginagak volcano. Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south-southwest of King Salmon, Alaska. This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks. The eruptive products of Chiginagak volcano record a history of chiefly andesite lava flows and associated block-and-ash flows. The oldest lavas exposed are Pleistocene in age and are found everywhere around the edifice except in the northeast sector, where Holocene lava flows dominate the landscape. Holocene activity has covered the northeast flank with rubbly-topped andesite lava flows that extend as far as 4.6 km from their source vent at the summit crater. The farthest-reaching volcanic deposits are on the southeast flank, where block-and-ash-flow, pyroclastic-flow, and lahar deposits extend down valley as far as 9 km from the summit. Limited exposure of deposits of a presumed plinian eruption of middle Pleistocene age indicate at least one episode of explosive activity in Chiginagak's past. This 1:25,000 scale geologic map and accompanying report document the age, geochemical, and spatial distribution of eruptive products of the Mount Chiginagak volcano. Map units are interpreted from field observations, satellite imagery interpretation, geochemical and geochronological analysis. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/29769.