Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska

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Frequently-anticipated questions:


What does this data set describe?

Title:
Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska
Abstract:
This dataset consists of the vector digital GIS files that were used to create sheet 1 of the "Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska" (DGGS RI 2004-3). The map area is centered around Okmok Volcano, on eastern Umnak Island. The data includes volcano-hazard zones for ballistics, ash accumulation, pyroclastic flows, floods and lahars, and debris avalanches. Also included in the dataset are roads, trails, seismic station locations, continuous GPS station locations, creeks, and the location of the Fort Glenn airstrip.
Supplemental_Information:
The basemap for the vector files included in this dataset is a georeferenced shaded relief tiff image whose metadata can be found in the file RI2004-3_basemap.faq.html. The 18 files listed below are available in both MapInfo TAB and ESRI shapefile format. Attribute information for the following layers (entities) is included in this metadata file under the "Entity_and_Attribute_Information" section. Each layer is listed and described in detail under its own heading starting "Entity_Type_Label." Listed here are the file names and a brief description of their content:
OKConeA5km_polyline      approximate hazard zone for ballistics from Cone A
OKContinuousGPS_point      location of continuous GPS stations
OKCraterCrFlood_polyline      approximate limits of Crater Creek Flood hazard zone
OKCreeks_polyline      major creeks around Okmok Volcano
OKDebrisArrows_polyline      arrows showing the approximate location and direction of flow of debris avalanches that could occur on the steep flanks of Tulik Volcano and the inner caldera walls of Okmok Volcano
OKDebrisTDA_polyline      mapped boundary of a prehistoric debris avalanche from Tulik Volcano
OKDebrisTulik_region      approximate hazard zone for debris avalanches with source areas on the steep flanks of Tulik Volcano
OKFlood_region      approximate location of flood and lahar hazards
OKFtGlennAir_point      location of the Fort Glenn airstrip
OKHazMapBdry_polyline      outline of the basemap
OKLatLines_polyline      four 10-minute latitude lines in the map area
OKLongLines_polyline      four 20-minute longitude lines in the map area
OKPFsurge_polyline      approximate location of pyroclastic flow and surge hazard zone
OKRim15km_polyline      approximate limit of significant ashfall, located 15 kilometers from the caldera rim
OKRim30km_polyline      approximate maximum extent of pyroclastic flows, sures, and lateral blasts during a very large eruption, located 30 kilometers from the caldera rim
OKroad_polyline      unmaintained dirt roads
OKSeisStat_point      location of seismic stations
OKtrail_polyline      unmaintained trails
  1. How should this data set be cited?

    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, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:150,000

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -168.7576
    East_Bounding_Coordinate: -167.5153
    North_Bounding_Coordinate: 53.7312
    South_Bounding_Coordinate: 53.1099

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2004
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 2
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -171.0000
      Latitude_of_Projection_Origin: 0.0000
      False_Easting: 500000.0000
      False_Northing: 0.0000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.01
      Ordinates (y-coordinates) are specified to the nearest 0.01
      Planar coordinates are specified in meters

      The horizontal datum used is WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    OKConeA5km_polyline.shp
    One polyline object representing a 5-kilometer-diameter circle around cone A, centered on (x,y)deg = (-168.2415, 53.3992); (x,y)meters = (683,393E, 5,920,230N). (Source: DGGS RI 2004-3)

    OKContinuousGPS_point.shp
    Three data points, each with station name, latitude, longitude, and elevation. Latitude and longitude have a WGS84 datum; elevation is in meters. (Source: Data provided by Jeff Freymueller, UAF Geophysical Institute, in September 2001, in cooperation with the Alaska Volcano Observatory.)

    station
    Continuous GPS station name (Source: Alaska Volcano Observatory)

    List of station names

    longwgs84
    longitude value of continuous GPS station location in decimal degrees using the WGS84 datum (Source: Alaska Volcano Observatory)

    longitude value

    latwgs84
    latitude value of continuous GPS station location in decimal degrees using the WGS84 datum (Source: Alaska Volcano Observatory)

    latitude value

    elev_meters
    elevation in meters above mean sea level of continuous GPS station using the WGS84 datum (Source: Alaska Volcano Observatory)

    elevation value

    OKCraterCrFlood_polyline.shp
    One polyline object representing the approximate limits of the Crater Creek flood hazard zone. (Source: DGGS RI 2004-3)

    OKCreeks_polyline.shp
    52 polyline objects representing major drainages around Okmok Volcano. (Source: USGS Umnak Island 1:250,000-scale topographic map)

    CreekName
    Name of the creek as derived from USGS Umnak Island 1:250,000-scale topographic map and Byers, F.M., 1959, Geology of Umnak and Bogoslof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-L. (Source: Byers, F.M., 1959, Geology of Umnak and Bogoslof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-L; and USGS 1:250,000-scale topographic basemap series, Umnak Island quadrangle, Alaska.)

    Not all line objects have creek names. Major creeks are named, others are unnamed.

    OKDebrisArrows_polyline.shp
    20 polyline objects. 20 randomly placed arrows indicating source regions for rockfalls and debris avalanches on the steep slopes of Tulik Volcano and the inner caldera walls of Okmok Volcano. (Source: DGGS RI 2004-3)

    OKDebrisTDA_polyline.shp
    One polyline object. Mapped boundary of a prehistoric debris avalanche from Tulik Volcano. (Source: DGGS RI 2004-3)

    OKDebrisTulik_region.shp
    One region object. Approximate hazard zone for debris avalanches with source areas on the steep flanks of Tulik Volcano. (Source: DGGS RI 2004-3)

    OKFlood_region.shp
    One region object. Approximate location of flood and lahar hazards. (Source: DGGS RI 2004-3)

    OKFtGlennAir_point.shp
    One point object. Approximate location of Fort Glenn airstrip. (Source: DGGS RI 2004-3)

    OKHazMapBdry_polyline.shp
    One polyline object. Outline of basemap OKhazbase.tiff. (Source: DGGS RI 2004-3)

    OKLatLines_polyline.shp
    4 line objects. 10-minute lines of latitude covering the map area. (Source: DGGS RI 2004-3)

    LatDMSWGS84
    Latitude in degrees, minutes, seconds (Source: DGGS RI 2004-3)

    values of latitude

    OKLongLines_polyline.shp
    4 line objects. 20-minute lines of latitude covering the map area. (Source: DGGS RI 2004-3)

    LongDMSWGS84
    Longitude in degrees, minutes, seconds (Source: DGGS RI 2004-3)

    values of longitude

    OKPFsurge_polyline.shp
    One polyline object. Approximate location of pyroclastic flow and surge hazard zone. (Source: DGGS RI 2004-3)

    OKRim15km_polyline.shp
    One polyline object. Approximate limit of significant ashfall, located 15 kilometers from the caldera rim. (Source: DGGS RI 2004-3)

    OKRim30km_polyline.shp
    One polyline object. Approximate maximum extent of pyroclastic flows, surges, and lateral blasts during a very large eruption, located 30 kilometers from the caldera rim. (Source: DGGS RI 2004-3)

    OKroad_polyline.shp
    Two polyline objects. Unmaintained dirt roads. (Source: Digitized from USGS Umnak Island 1:250,000-scale topographic map)

    OKSeisStat_point.shp
    12 points. Latitude, longitude, and station name of 12 seismic stations around Okmok Volcano. (Source: Alaska Volcano Observatory)

    station
    seismic station name (Source: Alaska Volcano Observatory)

    List of station names

    longwgs84
    longitude value of seismic station location in decimal degrees using the WGS84 datum (Source: Alaska Volcano Observatory)

    longitude value

    latwgs84
    latitude value of seismic station location in decimal degrees using the WGS84 datum (Source: Alaska Volcano Observatory)

    latitude value

    OKtrail_polyline.shp
    Two polyline objects. Unmaintained trails. (Source: Digitized from USGS Umnak Island 1:250,000-scale topographic map)


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?

    This dataset was compiled by the authors with funds from the Alaska Volcano Observatory, a joint program of the U.S. Geological Survey, the University of Alaska Fairbanks-Geophysical Institute, and the Alaska Division of Geological & Geophysical Surveys.

  3. To whom should users address questions about the data?

    State of Alaska, Division of Geological & Geophysical Surveys
    Alaska Volcano Observatory Geologist III
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907) 451-5010 (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 address all comments or questions to the e-mail address above whenever possible.


Why was the data set created?

This dataset was created to illustrate, at a scale of 1:150,000 the approximate location of volcanic hazard zones around Okmok Volcano.


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: Sep-2004 (process 1 of 1)
    Geologic field investigations were conducted by the authors to determine the eruptive history and the geographic extent of volcanic deposits at Okmok Volcano. Based on these field investigations and the knowledge of volcanic events at other volcanoes, the volcano hazard zones were determined for Okmok Volcano. Hazard zones were digitized in a GIS using the shaded relief image (OKhazbase.tiff) as a guide. Flood and lahar hazard zones were sketched from drainage patterns apparent on the Landsat7 GeoTIFF L72077023_023320000817_B80 of Umnak Island, acquired on 17 August 2000. The file was converted to red band 5, green band 4, and blue band 2 to enhance drainage patterns.

    Person who carried out this activity:

    State of Alaska, Division of Geological & Geophysical Surveys
    c/o Janet R. Schaefer
    Alaska Volcano Observatory, Geologist III
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907) 451-5010 (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 address all comments or questions to the e-mail address above whenever possible.
  3. What similar or related data should the user be aware of?


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

  1. How well have the observations been checked?

    Attributes in this dataset consist of GPS and seismic station names and locations, latitude and longitude line labels, and creek names. The accuracy was checked by plotting the attributes as labels in a GIS, then checking the label against the source information. Seismic and GPS station locations and names were checked using the original source data. The latitude and longitude line labels were checked by displaying them in GIS and comparing the attribute value to the actual location. The creek labels were plotted then compared to the USGS 1:250,000-scale topographic map of Umnak Island. Creek names were also derived and visually checked from Byers, F.M., 1959, Geology of Umnak and Bogoslof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-L, p. 167-369.

  2. How accurate are the geographic locations?

    The accuracy of the estimated extent of any of the volcanic hazard zones should not be confused with the horizontal accuracy of the GIS data file. For example, the 5 kilometer circle drawn around cone A for ballistics hazards is positionally accurate to about 550 meters, based on the estimated "center" of cone A, however, ballistics could possibly travel much shorter or much longer distances, depending on the eruption magnitude (see text for details of each eruption hazard, DGGS RI2004-3). Most data layers were digitized on the shaded relief image OKhazbase.tiff, which has a horizontal accuracy of 60 meters (see metadata file RI2004-3_basemap_meta.txt) Each GIS layer is listed below with a brief description of its horizontal accuracy. OkmokConeA5km_polyline A 5 km circle was generated around the center point of Cone A. The center of cone A was approximated visually from the georeferenced shaded relief basemap image (OKhazbase.tiff). Accuracy is approximately 550 meters, which is the vent diameter. Cone A center (x,y)deg = (-168.2415, 53.3992); (x,y)meters = (683,393E, 5,920,230N). OKContinuousGPS_point Continuous GPS station locations are accurate to approximately 1 centimeter. OKCraterCrFlood_polyline This approximated hazard zone was sketched from the shaded relief image basemap and is based on field evidence of drainage patterns of lahars and floods down Crater Creek over the last approximately 2,000 years. OKCreeks_polyline Creeks were originally digitized from the USGS 1:250,000-scale georeferenced DRG topographic map of Umnak Island. The creeks were reprojected in MapInfo version 6.0 from the raster topo base of UTM NAD27 to UTM WGS84 to match the projection of the shaded relief basemap (OKhazbase.tiff). After reprojection the creeks were hand-edited in GIS and required adjustments up to 150 meters to fit the shaded relief basemap (OKhazbase.tiff). OKDebrisArrows_polyline Debris arrows are randomly placed on the steep flanks of Tulik Volcano and the inner caldera wall of Okmok Volcano. OKDebrisTDA_polyline This boundary is based on field geologic mapping at a scale of 1:63,360 and photo-interpretation resulting in a horizontal accuracy of about 500 meters. OKDebrisTulik_region This generalized boundary is based in part on the extent of the prehistoric debris avalanche at Tulik Volcano (file OKDebrisTDA). OKFlood_region Flood and lahar hazard zones were sketched from drainage patterns apparent on the Landsat7 GeoTIFF L72077023_023320000817_B80 of Umnak Island, acquired on 17 August 2000. The file was converted to red band 5, green band 4, and blue band 2 to enhance drainage patterns. Drainages with headwaters on the high flanks of the volcano are portrayed. OKFortGlennAir_point Location derived from USGS 1:250,000-scale Umnak Island quadrangle DRG topographic map. Accuracy approximately 150 meters. OKHazMapBdry_polyline Outline of OKhazbase.tiff, accurate to pixel size of OKhazbase.tiff (30 meters). OKLatLines_polyline Generated in GIS from decimal degree end points to an accuracy of 5 decimal points, or approximately 1 meter. OKLongLines_polyline Generated in GIS from decimal degree end points to an accuracy of 5 decimal points, or approximately 1 meter. OKPFsurge_polyline Centered 10 kilometers around cone A (cone A center accuracy about 550 meters) with an approximate 17 kilometer extension downslope out through the breach in the caldera. OKRim15km_polyline The approximate diameter of the somewhat circular caldera is 10 kilometers, therefore a 20-kilometer circle was generated in a GIS around the approximate center of the caldera. The center of the caldera was approximated visually in a GIS from the georeferenced shaded relief basemap (OKhazbase.tiff). Accuracy is approximately 1,500 meters. For this purpose, the caldera center was positioned at (x,y)deg = (-168.4372, 53.4348); (x,y)meters = (670,243E, 5,923,700N). OKRim30km_polyline The approximate diameter of the somewhat circular caldera is 10 kilometers, therefore a 35 kilometer circle was generated in a GIS around the approximate center of the caldera. The center of the caldera was approximated visually in a GIS from the georeferenced shaded relief basemap (OKhazbase.tiff). Accuracy is approximately 1,500 meters. For this purpose, the caldera center was positioned at (x,y)deg = (-168.4372, 53.4348); (x,y)meters = (670,243E, 5,923,700N) OKroad_polyline Roads were digitized from the USGS 1:250,000-scale Umnak Island quadrangle DRG topographic map, then reprojected from UTM NAD27 to UTM WGS84 in MapInfo version 7.0. Accuracy is approximately 150 meters. OKSeisStation_point Seismic stations were located with hand-held GPS units (accuracy less than 15 meters) except OKCD, OKFG, and OKCE, which were located with differentially corrected Trimble GPS units with an accuracy of less than 1 centimeter. OKtrail_polyline Trails were digitized from the USGS 1:250,000-scale Umnak Island quadrangle DRG topographic map, then reprojected from UTM NAD27 to UTM WGS84 in MapInfo version 7.0. Accuracy is approximately 150 meters.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    This dataset includes preliminary information pertaining to the volcanic hazards at Okmok Volcano, Umnak Island, Alaska.

  5. How consistent are the relationships among the observations, including topology?

    The latitude and longitude attributes of the seismic stations and GPS station files were reformatted so that the column labels were consistent and that both sets of data are reported in decimal degrees, WGS84 datum.


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 are 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. 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.

  1. Who distributes the data set? (Distributor 1 of 1)

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    Natural Resource Technician
    3354 College Road
    Fairbanks, AK 99709-3707
    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 web site (<http://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?

    Report of Investigation 2004-3

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services 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, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requester or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    Please check the MapInfo web site (<http://www.mapinfo.com/>) for the latest documentation on importing ESRI shape files.


Who wrote the metadata?

Dates:
Last modified: 06-May-2008
Last Reviewed: 06-May-2008
To be reviewed: 03-Oct-2009
Metadata author:
State of Alaska, Division of Geological & Geophysical Surveys
c/o Janet R. Schaefer
Alaska Volcano Observatory Geologist III
3354 College Road
Fairbanks, AK 99709-3707
USA

(907) 451-5010 (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 contact us through the e-mail address above whenever possible.
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.6 on Tue May 06 14:29:39 2008