Identification_Information: Citation: Citation_Information: Originator: Loewen, M.W. Originator: Dietterich, H.R. Originator: Lubbers, Jordan Originator: Van Eaton, A.R. Publication_Date: 2025 Title: Tephra samples and analyses from the 2018-2023 eruption of Semisopochnoi Volcano, Alaska Geospatial_Data_Presentation_Form: spreadsheet Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2025-15 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 13 p. Online_Linkage: https://doi.org/10.14509/31645 Description: Abstract: Tephra samples and analyses from the 2018-2023 eruption of Semisopochnoi Volcano, Alaska, Raw Data File 2025-15, includes samples and analyses collected from the 2018-2023 eruption of Semisopochnoi volcano in the western Aleutian Islands, Alaska. Samples were collected during two field visits: May 30 to June 1, 2021, and June 10, 2023. A total of sixteen samples were collected across Semisopochnoi Island at varying distances from the eruption source, the north crater of Mount Young. Samples were collected from the surface on snow, grass, or other substrates that suggested deposition during recent eruptive activity but are, in all cases, aggregates of prior eruption events up to the sample date and may contain minor wind-blown contamination from older surfaces. These data and report are available from the DGGS website: http://doi.org/10.14509/31645 and a subset of the results are archived in the Geologic Database of Information on Volcanoes in Alaska (GeoDIVA; Cameron and others, 2022, doi.org/10.14509/geodiva). Purpose: These data describe the nature of samples from a past eruption to aid in discussing Alaska volcanism's spatial and temporal patterns. In addition, the work supports improvements to eruption scenario forecasts and hazard response. Supplemental_Information: >data: Analytical lab data and accompanying data dictionary Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 2021 Ending_Date: 2025 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: 179.492357 East_Bounding_Coordinate: 179.729819 North_Bounding_Coordinate: 52.001188 South_Bounding_Coordinate: 51.917959 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: Aeolian Theme_Keyword: Aleutian Arc Theme_Keyword: Analyses Theme_Keyword: Analyses and Sampling Theme_Keyword: Analytical Lab Results Theme_Keyword: Analytical Results Theme_Keyword: Ashfall Theme_Keyword: Chemistry Theme_Keyword: Coastal Theme_Keyword: Coastal and River Theme_Keyword: DGGS Theme_Keyword: Geochemical Data Theme_Keyword: Geochemistry Theme_Keyword: Geologic Theme_Keyword: Geologic Hazards Theme_Keyword: Geological Process Theme_Keyword: Geology Theme_Keyword: Grain Size Theme_Keyword: Hazards Theme_Keyword: Igneous Theme_Keyword: Lab Methods Theme_Keyword: Magmatic Arc Theme_Keyword: Major Oxides Theme_Keyword: Methods Theme_Keyword: Microprobe Analysis Theme_Keyword: Minor Oxides Theme_Keyword: Pyroclastic Fall Theme_Keyword: Pyroclastics Theme_Keyword: Sample Location Theme_Keyword: Surface Theme_Keyword: Tephra Theme_Keyword: Volcanic Theme_Keyword: Volcanic Arc Theme_Keyword: Volcanic Ash Theme_Keyword: Volcanic Eruption Theme_Keyword: Volcaniclastic Deposits Theme_Keyword: Volcaniclastics Theme_Keyword: Volcanoes Theme_Keyword: Volcanology Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Aleutian Islands Place_Keyword: Semisopochnoi Place_Keyword: Semisopochnoi Island 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: Metadata 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_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 (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible. Data_Set_Credit: Field sampling in 2021 and 2023 was conducted in association with Alaska Volcano Observatory geophysical monitoring network maintenance, with logistical support from field engineers on the joint mission. The 2021 work was supported by the crew of the R/V Steadfast and helicopter pilot Mike Grover. The 2023 work was supported by the crew of the R/V Tiglax. Simone Montayne provided metadata review. Kristi Wallace, Cheryl Cameron, and Scott Crass provided data and subject matter metadata review. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Cross_Reference: Citation_Information: Originator: Cameron, C.E. Originator: Crass, S.W. Originator: AVO Staff Publication_Date: 2022 Title: Geologic Database of Information on Volcanoes in Alaska (GeoDIVA) Series_Information: Series_Name: Digital Data Series Issue_Identification: DDS 20 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Online_Linkage: https://doi.org/10.14509/30901 Cross_Reference: Citation_Information: Originator: Loewen, M.W. Originator: Wallace, K.L. Originator: Lubbers, Jordan Originator: Ruth, Dawn Originator: Izbekov, P.E. Originator: Larsen, J.F. Originator: Graham, Nathan Publication_Date: 2023 Title: Glass electron microprobe analyses methods, precision and accuracy for tephra studies in Alaska Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 174 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 20 p Online_Linkage: https://doi.org/10.14509/31045 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The accompanying report and data tables provide a comprehensive discussion of processing methods, with errors reported in the tables where applicable. This data is being released as part of the DGGS RDF series, which includes content describing approved techniques and methods for the collection, storage, visualization, analysis, and interpretation of scientific data. While the information has been reviewed by several geologists familiar with the study area, the data and report have not undergone formal review for technical content or conformity to DGGS editorial standards. For inquiries regarding analytical values or procedures, the originating lab is the best point of contact. Logical_Consistency_Report: Not applicable Completeness_Report: This data release is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Sample location coordinates were obtained using recreational-grade GPS units, with a typical reported accuracy of about 10 meters. Lineage: Process_Step: Process_Description: Sample collection - Samples were collected in 2021 and 2023. Locations were recorded using tablet-integrated GPS with an accuracy of approximately 10 meters. In early summer 2021, ash deposits forming a distinct layer atop clean snow from winter 2020 through spring 2021 were sampled at three field sites. Two sites (21SMHD19 and 21SMHD07) were sampled within 30 x 30 cm squares, and one site (21SMHD12B) within a 20 x 20 cm square. Ash and snow were placed in gallon-sized sealable plastic bags, gravity-filtered using Whatman 541 filter paper, and dried at 40-50 degrees C for over 24 hours prior to weighing. Station identifiers (StationID) were assigned to sample locations and general observation sites. Sample identifiers (SampleID) refer to individual samples and include descriptive details. Laboratory identification numbers (at_num) were assigned during processing and analysis. Process_Date: 2024 Process_Step: Process_Description: Analytical methods - Grain size distributions for nine bulk samples were assessed using three techniques: standard sieving, laser diffraction particle size analysis, and dynamic image analysis. Tephra samples were embedded in epoxy and polished for electron probe microanalysis (EPMA) at the Alaska Tephra Laboratory. EPMA was conducted at the University of Alaska Fairbanks Advanced Instrumentation Laboratory using a JEOL JXA 8530F electron microprobe. For each sample, polished epoxy mounts were prepared for three particle size fractions: 63-125 micrometer, 125-250 micrometer, and 250-500 micrometer. These fractions were qualitatively examined using a JEOL 6510LV scanning electron microscope at the Alaska Tephra Laboratory. Process_Date: 2025 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.0000001 Longitude_Resolution: 0.0000001 Geographic_Coordinate_Units: decimal degrees Geodetic_Model: Horizontal_Datum_Name: WGS84 Ellipsoid_Name: WGS 84 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257223563 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: rdf2025_015_data.xlsx, rdf2025_015_data_dictionary.xlsx Entity_Type_Definition: Analytical lab data and accompanying data dictionary Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: data Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: Metadata 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_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 (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible. Resource_Description: RDF 2025-15 Distribution_Liability: The State of Alaska makes no expressed 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. Standard_Order_Process: Non-digital_Form: DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount. Fees: Contact DGGS for current pricing Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: spreadsheet Format_Version_Date: 20250801 Format_Information_Content: table Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/31645 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20250801 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Person: Simone Montayne Contact_Position: Metadata 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_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 Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Use_Constraints: If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. 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: https://dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions