Nye, Chris 2017 digital data Miscellaneous Publication MP 163 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 1 sheet http://doi.org/10.14509/29733 The 2008 eruption of Kasatochi volcano caused major topographic changes to Kasatochi Island, making all prior topographic maps and data obsolete. The topographic map and data presented here are derived from stereoscopic satellite images acquired on April 18, 2009. Subsequent topographic data has not been acquired, although there has been substantial topographic modification to the island, particularly to the shoreline, since these data were acquired. The purpose of this data release is to provide updated topographic data for Kasatochi Island subsequent to the August 6-8, 2008 explosive eruption of Kasatochi volcano. The eruption increased the area of the island by about 40 %; the crater by about 30 %; and the crater lake by nearly 70 % (Scott and others, 2010). The area of the island was increased by deposition of pyroclastic deposits which extended the preexisting shoreline seaward by up to four hundred meters. The area enclosed by the crater rim was increased primarily by explosive removal of preexisting rock and redeposition of that material in pyroclastic deposits on the flanks of the volcano. In addition, the entire island was blanketed by pyroclastic deposits, which are generally not thick enough to obscure pre-existing topography, but locally reach thicknesses of up to fifty meters (Nye and others, 2017). The eruption made all existing topographic data and maps obsolete. This report provides updated topography based on a stereo pair of satellite images acquired eight months after the eruption. There has been erosional modification of the island since these data were acquired. The western, northern, and eastern shores were progressively eroded (Nye and others 2017) and now consist either of pre-existing lava outcrops or boulder beaches back by near-vertical bluffs up to 25 m high cut into 2008 pyroclastic deposits. Between 2009 and 2012 the southernmost beach was extended seaward. An extensive system of gullies formed in the 2008 eruption deposits immediately after the eruption; these gullies have deepened and widened in subsequent years, but lateral shifts have been minimal. Post-2009 elevation data necessary for updating this map has not been acquired. Pertinent references: Scott, W.E., Nye, C.J., Waythomas, C.F., and Neal, C.A., 2010, August 2008 eruption of Kasatochi Volcano, Aleutian Islands, Alaska-Resetting an island landscape: Arctic, Antarctic, and Alpine Research, v. 42, no. 3, p. 250-259, http://doi.org/10.1657/1938-4246-42.3.250 and Nye, C.J., Scott, W.E., Neill, O.K., Waythomas, C.F., Cameron, C.E., and Calvert, A.T., 2017, Geology of Kasatochi volcano, Aleutian Islands, Alaska: Alaska Division of Geological & Geophysical Surveys Professional Report 123, http://doi.org/10.14509/29718 >map_files: Geodatabase and ArcMap document file used to generate the April 18, 2009, topographic map of Kasatochi Island. Attribute fields in the geodatabase feature classes are generally named and organized according to the NCGMP09 - Draft Standard Format for Digital Publication of Geologic Maps, Version 1.1 by the USGS National Cooperative Geologic Mapping Program (NCGMP). >map_image: GeoTIFF export of the April 18, 2009, topographic map of Kasatochi Island. >elevation_data: Digital elevation models (DEM) of Kasatochi Island derived from stereoscopic satellite images acquired on April 18, 2009. Files include: 1) the originating DEM, which is based on the WGS84 ellipsoid, and an adjusted version which uses Kasatochi Mean Sea Level (KMSL) as a vertical datum. 2009 2017 ground condition complete None planned -175.533179 -175.489901 52.186060 52.155519 ISO 19115 Topic Category geoscientificInformation Alaska Division of Geological & Geophysical Surveys Digital Elevation Model Geodatabase Geology Geomorphology Satellite Shaded Relief Surface Topography Volcanoes Alaska Division of Geological & Geophysical Surveys Aleutian Islands Atka Quadrangle Kasatochi 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 Holocene 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). 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. Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5039 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays The Kasatochi Mean Sea Level vertical datum was established with the assistance of Nicole Kinsman. Cartographic guidance provided by Patricia Gallagher. Satellite data credit: the DEM was derived from an orthorectified stereoscopic pair of April 18, 2009 WorldView-1 images; the 2004 shoreline was digitized from an orthorectified April 9, 2004 QuickBird-2 image; the 2012 shoreline was digitized from an orthorectified February 2, 2012 WorldView-2 image, and gullies were digitized from April 18, 2009 WorldView-1 images. Geographic place names are all informal, and are from, or derived from, place names customarily used by US Fish and Wildlife researchers, who are the primary visitors to the island. Nye, C.J. Scott, W.E. Neill, O.K. Waythomas, C.F. Cameron, C.E. Calvert, A.T. 2017 Professional Report PR 123 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 1 sheet http://doi.org/10.14509/29718 Certainty in attribute interpretation may vary throughout the map. Attribute fields within each geodatabase feature class record the author's degree of confidence in the existence or identity of applicable features. The information has been examined by several geologists familiar with the study area, but the data and accompanying report have not been formally reviewed for technical content or for conformity to the editorial standards of DGGS. All data are derived from a small number of satellite images, insuring a high level of internal consistency. Data from disparate sources were not combined. This data release is complete. Note: the presence of small clouds in the original satellite images make derived elevation data in the southeast crater wall unreliable. Locations of several features easily identifiable on the satellite images, such as shorelines, the crater rim, gully intersections, and distinctive outcrops were measured during the course of the study with hand-held GPS units. Features on gentle terrain were found to be displayed on the images within the resolution of the hand held GPS, and the topographic data match the images to within a meter or less. From this we conclude that horizontal precision in areas of gentle terrain is generally within 1 meter. In areas of steep or near-vertical terrain the topographic data diverge from the satellite images by up to tens of meters, but we are unable to independently determine if these differences are due to lack of accuracy of the elevation data or parallax in the images. For display purposes, the vertical elevations on the topographic map are referenced to an estimated local tidal datum, Mean Sea Level at Kasatochi (KMSL). The local MSL datum is a linear correction defined by the 10:21 June 15, 2009 water level at AVO benchmark KAS4 and the tidal predictions at the Fenimore Pass subordinate tidal station (9461519). Conversion factors for this local datum and common ellipsoids are: add 8.3 meters to Kasatochi MSL (map datum) to obtain WGS84 or ITRF2008 elevations (m); add 7.3 m to Kasatochi MSL (map datum) to obtain NAD83(2011) elevations (m). Acquire 2009 satellite data - WorldView-1 stereo satellite imagery (60 cm spatial resolution) were captured on April 18, 2009 and subsequently acquired by the Alaska Volcano Observatory (AVO). 2009 Establish ground control - Trimble 5700 campaign GPS receivers were used to establish four sites at points that were easily recognizable on the satellite imagery. A base station on the island was continually operated during campaign data collection. Data were reduced by AVO at the UAF Geophysical Institute (Jeff Freymueller). 2009 WGS84 DEM creation - A DEM relative to WGS84 ellipsoid was created by commercial vendor (i-cubed, LLC) using April 18, 2009 stereo satellite images and GPS control points. 2010 KMSL DEM creation - In the process of working with the WGS84 DEM it became clear that at Kasatochi the ellipsoid is substantially different than the actual ground surface. We used field photographs to estimate the elevation of a campaign GPS site located on a boulder embedded in a beach relative to sea level. Then we used the time and date of the field photographs to estimate the tidal stage assuming that the Fenimore Pass tidal station accurately represented the tidal stage at Kasatochi. This indicated an offset between the WGS84 ellipsoid and the local earth surface of 8.3 m. We subtracted 8.3 m from the WGS84 DEM to yield a DEM with Kasatochi Mean Sea Level (KMSL) as a vertical datum. The tidal range at Kasatochi is small, about 0.5 m on the day the reference photograph was taken, so small differences in timing between the tidal stage at Fenimore Pass and Kasatochi would introduce only small error in estimating the difference between WGS84 and KMSL vertical datums. 2013 Creating contour lines and mapping - Contour lines were produced using the Contour tool in ArcMap 10.4. Gullies were digitized from the orthorectified satellite images used to create the DEM in two classes; 1-5 m (2-10 pixels) wide (thin lines) and >5 m (>10 pixels) wide (thick lines). 2004 and 2012 coastlines were digitized from the appropriate satellite images. 2016 Refinement of KMSL DEM - Shoreline artifacts were removed from the DEM 2016 point Universal Transverse Mercator 1 0.999600 -177 0 500000.000000 0 coordinate pair .00000001 .00000001 Meters World Geodetic System of 1984 WGS 84 6378137 298.257223563000025 Mean Sea Level 2 meter Implicit coordinate map_files Geodatabase and ArcMap document file used to generate the April 18, 2009, topographic map of Kasatochi Island. Attribute fields in the geodatabase feature classes are generally named and organized according to the NCGMP09 - Draft Standard Format for Digital Publication of Geologic Maps, Version 1.1 by the USGS National Cooperative Geologic Mapping Program (NCGMP). File format: .tif. Alaska Division of Geological & Geophysical Surveys (DGGS) and Alaska Volcano Observatory staff map_files map_image GeoTIFF export of the April 18, 2009, topographic map of Kasatochi Island. File format: .tif. Alaska Division of Geological & Geophysical Surveys (DGGS) and Alaska Volcano Observatory staff map_image elevation_data Digital elevation models (DEM) of Kasatochi Island derived from stereoscopic satellite images acquired on April 18, 2009. Files include: 1) the originating DEM, which is based on the WGS84 ellipsoid, and an adjusted version which uses Kasatochi Mean Sea Level (KMSL) as a vertical datum. File format: .tif. Commercial vendor (i-cubed, LLC) created the originating DEM. Ground control data were reduced by Jeff Freymueller (AVO at the UAF Geophysical Institute). The DEM was adjusted to use Kasatochi Mean Sea Level by Alaska Division of Geological & Geophysical Surveys (DGGS) and Alaska Volcano Observatory staff. elevation_data Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5039 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays MP 163 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. 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. Contact DGGS for current pricing Raster data and ArcGIS map files http://doi.org/10.14509/29733 Free download 20170821 Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5039 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 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. http://www.dggs.alaska.gov/metadata/dggs.ext dggs metadata extensions