Identification_Information: Citation: Citation_Information: Originator: Larsen, J.F. Originator: Neal, C.A. Originator: Schaefer, J.R. Originator: Kaufman, A.M. Originator: Lu, Zhong Publication_Date: 2015 Title: The 2008 phreatomagmatic eruption of Okmok Volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes Geospatial_Data_Presentation_Form: report and digital data Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2015-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 53 p. Online_Linkage: http://dx.doi.org/10.14509/29405 Description: Abstract: 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. Purpose: Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. This eruption was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977. These digital data files provide field station locations and depict various geographic features described in the accompanying report. Supplemental_Information: >border: A polygon shapefile that provides a generalized outline of the geographic area described by this report. >alluvial-channels: Pre-eruption active alluvial and fluvial channels from field mapping and various source satellite imagery >new-cone-crater-rim: Outline of new cone Ahmanilix's two crater rims, digitized from a September 22, 2008 Quickbird satellite image >new-cone-region: Polygon depicting new cone Ahmanilix; digitized from a September 22, 2008 Quickbird satellite image. The base of cone was digitized from apparent break in slope as interpreted from the September 22, 2008 Quickbird image. Subsequent erosion has changed the shape of the cone dramatically. >new-craters: Explosion crater rims and collapse crater rims as interpreted from fieldwork, post-eruption satellite images, and syn-eruption Synthetic Aperture Radar (SAR) imagery. >new-pits: Polygons outlining syn-eruptive collapse pits; digitized from a September 22, 2008 Quickbird satellite image. >new-vents: Approximate vent locations interpreted from fieldwork, post-eruption satellite images, and syn-eruption Synthetic Aperture Radar (SAR) imagery. Exact vent locations are uncertain, but are generally interpreted to lie within the region encompassed by the polygon feature. >post-2008-eruption-lakes: Polygons outlining areas of surface water after the 2008 eruption; digitized from a September 22, 2008 Quickbird satellite image. >pre-2008-eruption-lakes: Polygons outlining areas of surface water before the 2008 eruption; digitized from September 2000 IKONOS and August 2000 Landsat satellite imagery. >stations: Field sites visited in August and September of 2008; locations were acquired with hand-held GPS units. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 2008 Ending_Date: 2014 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -168.340761 East_Bounding_Coordinate: -166.463118 North_Bounding_Coordinate: 53.953138 South_Bounding_Coordinate: 53.199696 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: Active Volcanoes Theme_Keyword: Aleutian Arc Theme_Keyword: Ash Cloud Theme_Keyword: Ash Fall Theme_Keyword: Caldera Theme_Keyword: Geologic Hazards Theme_Keyword: Geomorphology Theme_Keyword: Geothermal Theme_Keyword: Groundwater Theme_Keyword: Heat Flow Study Theme_Keyword: Historic Eruption Theme_Keyword: Lahar Theme_Keyword: Lahar Runout Flow Theme_Keyword: Lake Level Theme_Keyword: Stratigraphy Theme_Keyword: Surface Water Theme_Keyword: Tephra Theme_Keyword: Volcanic Ash Theme_Keyword: Volcanic Eruption Theme_Keyword: Volcaniclastics Theme_Keyword: Volcanology Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Aleutian Islands Place_Keyword: Cone A Place_Keyword: Cone B Place_Keyword: Cone C Place_Keyword: Cone D Place_Keyword: Cone E Place_Keyword: Cone F Place_Keyword: Cone G Place_Keyword: Cone H Place_Keyword: Cone I Place_Keyword: Cone J Place_Keyword: Fort Glenn Place_Keyword: Okmok Place_Keyword: Okmok Caldera Place_Keyword: Okmok Hot Springs Place_Keyword: Okmok Volcano Place_Keyword: Okmok, Mount Place_Keyword: Umnak Island Place_Keyword: Umnak Quadrangle Place_Keyword: Unalaska Quadrangle Temporal: Temporal_Keyword_Thesaurus: Walker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of America Temporal_Keyword: Holocene Access_Constraints: This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below). Use_Constraints: Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: GIS Manager Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Electronic_Mail_Address: dggsgis@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Data_Set_Credit: We dedicate this Report of Investigations to Lonnie Kennedy and the Kennedy family of the Bering Pacific Ranch at Fort Glenn, in appreciation for their generous assistance during our field campaigns, and keen observations of Okmok volcano before, during, and after the 2008 eruption. The authors thank the Kennedy family for permission to use Lonnie's photographs and observations. Rick Wessels and Russ Rykhus are gratefully acknowledged for assistance with FLIR and SAR image acquisition and processing. We also thank helicopter pilots Bill Springer and Kenny Clark for safely flying us around the volcano, often in less than ideal weather, in 2008 and 2010. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the State of Alaska or U.S. Government. Cross_Reference: Citation_Information: Originator: Beget, J.E. Originator: Larsen, J.F. Originator: Neal, C.A. Originator: Nye, C.J. Originator: Schaefer, J.R. Publication_Date: 2005 Title: Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2004-3 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 32 p., 1 sheet, scale 1:150,000 Online_Linkage: http://dx.doi.org/10.14509/7042 Cross_Reference: Citation_Information: Originator: Schaefer, J.R. Publication_Date: 2005 Title: 30-meter shaded relief image of Okmok Volcano, Umnak Island, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2005-1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Online_Linkage: http://dx.doi.org/10.14509/7041 Cross_Reference: Citation_Information: Originator: Schaefer, J.R. Originator: Larsen, J.F. Originator: Unema, J.A. Publication_Date: 2012 Title: Digital elevation model (DEM) and shaded relief image of Okmok Caldera, 2010 Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2011-6 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Online_Linkage: http://dx.doi.org/10.14509/23223 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: This DGGS Report of Investigations is a final report of scientific research. It has received technical review by several scientists familiar with the subject matter. Uncertainties associated with the depiction or interpretation of various geospatial features are discussed in the manuscript. Logical_Consistency_Report: Not applicable Completeness_Report: This is a final report of scientific research. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Locations were collected by hand-held GPS units or digitized from imagery. Uncertainties associated with the location and extent of various geospatial features are discussed in the manuscript. Lineage: Process_Step: Process_Description: Geologic field observations and sampling - In response to the 2008 eruption, the Alaska Volcano Observatory (AVO) sent field teams to Okmok from July 31 through August 3, 2008, and from September 8 through 15, 2008. Teams gathered helicopter- and ground-based observations, documented new volcanic features and lake changes, and described stream-channel and shoreline modifications created by widespread lahar inundation. Samples and stratigraphic descriptions were collected at 50 locations in the caldera and on the volcano flanks. See Methods section 3.1 of the accompanying report for additional detail. Process_Date: 2008 Process_Step: Process_Description: Synthetic Aperture Radar (SAR) analysis - We utilized SAR backscatter intensity images to track surface modification during the course of the 2008 eruption. SAR images were acquired from European Space Agenc's Envisat satellite, a C-band sensor with a wavelength of about 5.6 cm. Terrain-corrected and georeferenced SAR images including delineated features caused by the 2008 eruption were imported into ArcGIS and compared with other geospatial data sets including a pre-eruption DEM, geologic mapping, and post-eruption Quickbird satellite imagery. Using a series of images spanning the timeframe of the eruption, we have interpreted the evolution of vents and other features during the course of activity. See Methods section 3.3 of the accompanying report for additional detail. Process_Date: 2008 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: vector Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 2 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -171 Latitude_of_Projection_Origin: 0 False_Easting: 500000.000000 False_Northing: 0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: .01 Ordinate_Resolution: .01 Planar_Distance_Units: Meters Geodetic_Model: Horizontal_Datum_Name: World Geodetic System of 1984 Ellipsoid_Name: WGS 84 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257223563 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: border Entity_Type_Label: ri2015-2-border.shp Entity_Type_Definition: A polygon shapefile that provides a generalized outline of the geographic area described by this report. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: alluvial-channels Entity_Type_Label: ri2015-2-alluvial-channels.shp Entity_Type_Definition: Pre-eruption active alluvial and fluvial channels from field mapping and various source satellite imagery Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: new-cone-crater-rim Entity_Type_Label: ri2015-2-new-cone-crater-rim.shp Entity_Type_Definition: Outline of new cone Ahmanilix's two crater rims, digitized from a September 22, 2008 Quickbird satellite image Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Attribute: Attribute_Label: COMMENT Attribute_Definition: Notes about the feature Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Notes in the comment field may include feature labels or additional description. If present, blank or null values indicate that labels or additional information were not applicable. Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: new-cone-region Entity_Type_Label: ri2015-2-new-cone-region.shp Entity_Type_Definition: Polygon depicting new cone Ahmanilix; digitized from a September 22, 2008 Quickbird satellite image. The base of cone was digitized from apparent break in slope as interpreted from the September 22, 2008 Quickbird image. Subsequent erosion has changed the shape of the cone dramatically. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: new-craters Entity_Type_Label: ri2015-2-new-craters.shp Entity_Type_Definition: Explosion crater rims and collapse crater rims as interpreted from fieldwork, post-eruption satellite images, and syn-eruption Synthetic Aperture Radar (SAR) imagery. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Attribute: Attribute_Label: COMMENT Attribute_Definition: Notes about the feature Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Notes in the comment field may include feature labels or additional description. If present, blank or null values indicate that labels or additional information were not applicable. Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: new-pits Entity_Type_Label: ri2015-2-new-pits.shp Entity_Type_Definition: Polygons outlining syn-eruptive collapse pits; digitized from a September 22, 2008 Quickbird satellite image. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: new-vents Entity_Type_Label: ri2015-2-new-vents.shp Entity_Type_Definition: Approximate vent locations interpreted from fieldwork, post-eruption satellite images, and syn-eruption Synthetic Aperture Radar (SAR) imagery. Exact vent locations are uncertain, but are generally interpreted to lie within the region encompassed by the polygon feature. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Attribute: Attribute_Label: COMMENT Attribute_Definition: Notes about the feature Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Notes in the comment field may include feature labels or additional description. If present, blank or null values indicate that labels or additional information were not applicable. Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: post-2008-eruption-lakes Entity_Type_Label: ri2015-2-post-2008-eruption-lakes.shp Entity_Type_Definition: Polygons outlining areas of surface water after the 2008 eruption; digitized from a September 22, 2008 Quickbird satellite image. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Attribute: Attribute_Label: COMMENT Attribute_Definition: Notes about the feature Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Notes in the comment field may include feature labels or additional description. If present, blank or null values indicate that labels or additional information were not applicable. Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: pre-2008-eruption-lakes Entity_Type_Label: ri2015-2-pre-2008-eruption-lakes.shp Entity_Type_Definition: Polygons outlining areas of surface water before the 2008 eruption; digitized from September 2000 IKONOS and August 2000 Landsat satellite imagery. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Attribute: Attribute_Label: UNIT Attribute_Definition: Unit designator from Geologic map of Okmok Volcano, in progress Attribute_Definition_Source: J. Schaefer, written communication, 2014 Attribute_Domain_Values: Unrepresentable_Domain: Features were classified as "lake" or "water." Attribute: Attribute_Label: COMMENT Attribute_Definition: Notes about the feature Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Notes in the comment field may include feature labels or additional description. If present, blank or null values indicate that labels or additional information were not applicable. Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: stations Entity_Type_Label: ri2015-2-stations.shp Entity_Type_Definition: Field sites visited in August and September of 2008; locations were acquired with hand-held GPS units. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory Attribute: Attribute_Label: StationID Attribute_Definition: Field station identification value Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Unique station id values; the numbering convention is determined by the geologist who provided the description. Attribute: Attribute_Label: Date_Visit Attribute_Definition: Date the site was visited Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 31-Jul-08 Range_Domain_Maximum: 16-Sep-08 Attribute_Units_of_Measure: DD-Mon-YY Attribute: Attribute_Label: Thick_cm Attribute_Definition: Thickness, in cm, of the 2009 tephra deposits Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.2 Range_Domain_Maximum: 1230 Attribute_Units_of_Measure: Centimeters Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: NULL Enumerated_Domain_Value_Definition: Blank (NULL) values indicate that tephra thickness was not measured at the station or that tephra observations were not applicable to that location. Enumerated_Domain_Value_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute: Attribute_Label: COMMENT Attribute_Definition: Notes about the station Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys and Alaska Volcano Observatory staff Attribute_Domain_Values: Unrepresentable_Domain: Notes in the comment field provide additional description of the location or indicate the type of measurement, sample, or work that was conducted that the station. Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Facsimile_Telephone: (907)451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Contact_Instructions: Please view our website (http://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible. 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User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys. Metadata_Extensions: Online_Linkage: http://www.dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions