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

Geologic map of Okmok Volcano, Report of Investigation 2023-1, provides 40Ar/39Ar and radiocarbon geochronology data from Okmok Volcano and its eruptive products. Okmok Volcano is one of 54 historically active volcanoes in the Alaska-Aleutian volcanic arc that stretches across southern mainland Alaska and the Aleutian Islands. Okmok Volcano dominates the northeastern portion of Umnak Island, which is 100 km southwest of Unalaska/Dutch Harbor and 1,400 km southwest of Anchorage. Okmok Volcano is one of the most frequently active volcanoes in the Aleutian volcanic arc. In 1998, the Alaska Volcano Observatory (AVO) began a multi-year effort to expand geophysical monitoring in the central Aleutians Islands, including at Okmok Volcano. These data support the development of a modern geologic map of Okmok Volcano and related investigation of its eruptive history and hazards. 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/10.14509/31015.

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.

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.

This publication provides digital point data for the locations of 127 volcanic centers in Alaska younger than 2 million years. Information about whether a volcano has been historically active is also provided. Detailed information about each center can be found on the Alaska Volcano Observatory website at http://www.avo.alaska.edu

DGGS Professional Report 126, The ~400 yr B.P. eruption of Half Cone, a post-caldera composite cone within Aniakchak caldera, Alaska Peninsula, presents an investigation of the ~400 yr B.P. Half Cone eruption. This eruption is the largest post-caldera eruption yet identified from the Aniakchak volcano. Our goals for this study are to (1) describe the dispersal and volume of the ~400 yr B.P. Half Cone eruption based on stratigraphic characteristics of the resulting deposits, (2) evaluate the pre-eruption storage conditions of magmas expelled during the ~400 yr B.P. Half Cone eruption based on both whole-rock geochemical analyses of juvenile material and in situ geochemical analyses of mineral and glass regions of deposits, and (3) synthesize stratigraphic and geochemical observations into a chronology for the ~400 yr B.P. eruption. All files are available from the DGGS website: http://doi.org/10.14509/30839.