Geologic map of Okmok Volcano

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What does this data set describe?

Title: Geologic map of Okmok Volcano
Abstract:
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.
Supplemental_Information:
Appendix A 40Ar/39Ar Ages of Okmok lavas: Field station locations and 40Ar/39Ar ages of Okmok lavas	
Appendix B Radiocarbon ages: Field station locations and radiocarbon ages used to interpret Okmok Volcano geologic map units	
Appendix C Stations and samples: Field station locations of samples discussed in this report
  1. How might this data set be cited?
    Larsen, J.F., Neal, C.A., Schaefer, J.R., and Nye, C.J., 2023, Geologic map of Okmok Volcano: Report of Investigation RI 2023-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 63 p., 4 sheets
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -168.399980
    East_Bounding_Coordinate: -167.753160
    North_Bounding_Coordinate: 53.562390
    South_Bounding_Coordinate: 53.280010
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1998
    Ending_Date: 2023
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: csv
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a point data set.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is NAD83.
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    AppendixA_OkmokArAr-data.csv, AppendixA_OkmokArAr-data-dictionary.csv
    Field station locations and 40Ar/39Ar ages of Okmok lavas (Source: DGGS)
    AppendixB_OkmokRadiocarbon-data.csv, AppendixB_OkmokRadiocarbon-data-dictionary.csv
    Field station locations and radiocarbon ages used to interpret Okmok Volcano geologic map units (Source: DGGS)
    AppendixC_StationsAndSamples.csv, AppendixC_StationsAndSamples-data-dictionary.csv
    Field station locations of samples discussed in this report (Source: DGGS)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    Geophysical Institute and the Alaska Division of Geological & Geophysical Surveys, currently Cooperative Agreement G19AC00171, and by USGS Volcano Hazards Program funding to the Alaska Volcano Observatory. We thank many geologists and geophysicists who provided their time, insights, and camaraderie at Fort Glenn in all kinds of weather, including Jim Beget, Deb Bergfeld, Alain Burgisser, Michelle Coombs, Cheryl Cameron, John Eichelberger, Jeff Freymueller, Rick Hazlett, Alexander Max Kaufman, David Lescinsky, Taryn Lopez, Doerte Mann, Steve McNutt, Michael Ort, and Guy Tytgat. Former undergraduate and graduate students who participated in the geology fieldwork at Okmok Volcano include a cohort from Pomona College and the University of Alaska Fairbanks: Leslie Almberg, Matt Patrick, Ben Finney, Delanora Grey, Ken Papp, Joel Unema, and Lily Wong. Reviews by Tim Orr, Julie Nolan, and Drew Downs provided helpful insight and are much appreciated. Bering Pacific Ranches Ltd. supported this work through lodging and logistics support. Access to Umnak Island was by charter flights or boat from the Port of Dutch Harbor. We thank Cliff Gill (Airborne Scientific), Don Graves (Miss Peppers), and Jimmer MacDonald (Miss Alyssa) for safe transport to Umnak Island in often challenging sea conditions. Maritime Helicopters and pilots Bill Springer, Rick Farrish, and Jon Combs made our work possible, providing efficient, safe, and professional transportation in the field area. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    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.

Why was the data set created?

This data describes the nature and character of samples from a past eruption to aid in the discussion of spatial and temporal patterns of Alaska volcanism. In addition, the work supports improvements to eruption scenario forecasts and hazard response.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2016 (process 1 of 3)
    Sample collection - A team of five geologists from AVO (UAF/GI and USGS partner agencies) conducted summer geologic fieldwork throughout Umnak Island from July 1998 to 2016.
    Date: 2017 (process 2 of 3)
    40Ar/39Ar Analytical Techniques - Rocks were submitted for 40Ar/39Ar age dating to the geochronology laboratories at the University of Alaska Fairbanks (UAF) and the USGS in Menlo Park. For 40Ar/39Ar analysis at UAF, 12 samples were dated, with the data yielding the isochron ages provided in the digital data; all ages are quoted to the +/-1-sigma level and calculated using the decay constants of Steiger and Jager (1977). The USGS Menlo Park geochronology lab analyzed 17 groundmass samples separated by crushing, sieving, and magnetic techniques, with 14 samples yielding interpretable results. Uncertainties in 40Ar/39Ar ages are also reported at the one-sigma level unless otherwise noted and include propagated uncertainties in counting statistics and J values. Lab methods and age interpretation calculations are described in detail in the accompanying report.
    Date: 2017 (process 3 of 3)
    Radiocarbon Analytical Techniques - Radiocarbon dating (conventional and Accelerator Mass Spectrometer [AMS]) of organic material to constrain eruption ages was carried out using Beta Analytic and Geochron Laboratories. Datable material was found typically in soils beneath tephra fall or pyroclastic density current deposits on the lower flanks of the volcano. Dating of wood and carbonized vegetation found within surge deposits was also possible in several cases. All samples were hand-cleaned thoroughly to remove modern plant material before submission to the lab. Soil samples were treated before analysis in the lab by dispersion in water, and isolating organic matter using agitation and ultrasound. Modern rootlets were screened with a nylon filter, and the remaining clay and organic fraction were subject to both acid and alkali washes. The humic acid fraction was precipitated, filtered, dried, and combusted in O2 to produce CO2 for analysis. The ages of the two caldera-forming eruptions are well constrained by this method. A compilation of dates and laboratories is provided in the digital data.
  3. What similar or related data should the user be aware of?
    Beget, J.E., Larsen, J.F., Neal, C.A., Nye, C.J., and Schaefer, J.R., 2005, Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska: Report of Investigation RI 2004-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 32 p., 1 sheet, scale 1:150,000
    Cameron, C.E., Mulliken, K.M., Crass, S.W., Schaefer, J.R., and Wallace, K.L., 2019, Alaska Volcano Observatory geochemical database, version 2: Digital Data Series DDS 8 v. 2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 22 p
    Larsen, J.F., Neal, C.A., Schaefer, J.R., Kaufman, A.M., and Lu, Zhong, 2015, The 2008 phreatomagmatic eruption of Okmok Volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes: Report of Investigation RI 2015-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 53 p
    Larsen, J.F., Schaefer, J.R., and Cameron, C.E., 2022, Electron probe microanalytical data of minerals and glass from rock samples from Okmok volcano, Alaska: Raw Data File RDF 2022-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 13 p
    Nye, C.J., Beget, J.E., Layer, P.W., Mangan, M.T., McConnell, V.S., McGimsey, R.G., Miller, T.P., Moore, R.B., and Stelling, P.L., 2018, Geochemistry of some quaternary lavas from the Aleutian Arc and Mt. Wrangell: Raw Data File RDF 2018-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 29 p
    Schaefer, J.R., 2005, 30-meter shaded relief image of Okmok Volcano, Umnak Island, Alaska: Raw Data File RDF 2005-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Schaefer, J.R., Larsen, J.F., and Unema, J.A., 2012, Digital elevation model (DEM) and shaded relief image of Okmok Caldera, 2010: Raw Data File RDF 2011-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The data tables provide calculated 2 sigma level uncertainty values for all ages and isotope ratios.
  2. How accurate are the geographic locations?
    AVO staff used handheld GPS units to acquire location coordinates. Positional uncertainty reported by the GPS units was not recorded.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This data releaase is complete.
  5. How consistent are the relationships among the observations, including topology?
    Not applicable

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
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.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    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.
  2. What's the catalog number I need to order this data set? RI 2023-1
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 06-Dec-2023
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK
USA

(907)451-5020 (voice)
(907)451-5050 (FAX)
dggspubs@alaska.gov
Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.50 on Wed Dec 06 18:57:01 2023