Alaska landslide inventory database

Nicolazzo, J.A.Larsen, M.C.2025Alaska landslide inventory databasedataDigital Data SeriesDDS 23Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys14 p.https://doi.org/10.14509/31697Alaska landslide inventory database, Digital Data Series 23, provides a catalog of slope instabilities across Alaska and documents the development of the Alaska Landslide Inventory (ALI), a geospatial database created by the Division of Geological & Geophysical Surveys (DGGS) under the State's Landslide Hazards Program. Initiated in response to recent catastrophic landslides, the ALI consolidates both published and newly identified landslide events, including those reported in media sources and interpreted from aerial imagery. Each entry is classified by movement type (e.g., slides, flows, thaw-related) and includes metadata such as event date, kinematic features, and confidence intervals. The inventory is designed to support hazard assessment, land-use planning, and risk mitigation efforts, and will be integrated into the national U.S. Landslide Inventory. This report outlines the methodology used to compile the database, discusses current limitations, and identifies future goals for expanding coverage, refining classifications, and improving data completeness. The ALI is intended for regional or community-scale analysis and is not suitable for site-specific or legal use. This data is released with an open end-user license. All files can be downloaded from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/31697).Accurate and accessible information about landslides is essential for understanding slope instability, reducing economic losses, and preventing fatalities across Alaska. In response to recent catastrophic events, the State of Alaska established the Landslide Hazards Program within the Division of Geological & Geophysical Surveys (DGGS) to assess and communicate landslide risks. A central initiative of this program is the Alaska Landslide Inventory (ALI), a geospatial database that compiles both published and newly identified landslides. By classifying events by movement type and including metadata such as event date, kinematic features, and confidence levels, the ALI provides a critical resource for planners, emergency managers, researchers, and policymakers. This evolving database helps identify landslide-prone areas and supports informed decision-making for hazard mitigation and land-use planning.>landslide_inventory_db: The dataset describes geographic features using mapped polygons classified by landslide movement type and annotated with metadata such as location, event date, and mapping method.2025publication dateIn WorkUnknown-180.000000180.00000071.39202951.217293ISO 19115 Topic CategorygeoscientificInformationAlaska Division of Geological & Geophysical SurveysCoastalCoastal and RiverCoastal ErosionColluviumDebris AvalancheDebris FlowDebris Flow DepositDGGSFanFracturingGelifluctionGeodatabaseGeologicGeologic HazardsGeological ProcessGeologyGeomorphologyGeotechnicalGlaciersGroundwaterHazardsInterpretationLand SubsidenceLandslideLandslide DepositLandslide SusceptibilityLiquefactionMethodsRegionalRock AvalancheRock FragmentsShearSlidesSlopeSlope InstabilitySlumpSolifluctionStructureSurfaceSurficialTalusTopographyTransportationTsunamiVegetationWaterAlaska Division of Geological & Geophysical SurveysAfognakAlaskaAlaska PeninsulaAlaska RangeAlaska Statewide QuadrangleAlaska, State ofAleutian IslandsAleutian PeninsulaAleutian RangeAnchorageBrooks RangeCopper RiverCopper River BasinFairbanksIliamnaJuneauKatmaiKenaiNoatakSeldoviaSewardSeward PeninsulaSouthcentral AlaskaSoutheast AlaskaTalkeetnaTyonekWhittierWrangell MountainsThis 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 SurveysMetadata Managermailing and physical

3354 College Road

FairbanksAK99709-3707USA(907)451-5020(907)451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysPlease 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.This project was funded through Cooperative Agreements between the Division of Geological & Geophysical Surveys (DGGS) and the U.S. Geological Survey, under grant numbers G21AC10362 and G24AC00114. We acknowledge the Washington State Department of Natural Resources and the Oregon Department of Geology and Mineral Industries, whose geodatabases served as valuable templates during development. Special thanks go to the many geologists whose decades of mapping and publications now form the foundation of this database. The views and conclusions expressed in this document are those of the authors and do not necessarily reflect the policies or opinions of the U.S. Government. Mention of trade names or commercial products does not imply endorsement by the U.S. Geological Survey. This report and database are submitted for publication with the understanding that the U.S. Government is authorized to reproduce and distribute reprints for governmental purposes.Larsen, M.C.Nicolazzo, J.A.Athey, J.E.2023Landslide hazards in AlaskaInformation CircularIC 96Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys2 phttps://doi.org/10.14509/31100Wikstrom Jones, K.M.Larsen, M.C.2025Susceptibility to deep-seated landslides in AlaskaPreliminary Interpretive ReportPIR 2025-3Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys5 p., 1 sheet, scale 1:3,750,000https://doi.org/10.14509/31691The Alaska Landslide Inventory (ALI) database compiles landslide data from diverse sources with varying goals, mapping methods, and scales, resulting in inconsistencies and potential errors inherited from original publications, digitization processes, and georeferencing challenges. Most data were mapped at scales between 1:24,000 and 1:500,000, and users are advised to respect these scales to avoid misinterpretation. Because no field verification was conducted, the reliability of the data depends on the accuracy of the original geologic work. Coverage across Alaska is uneven, with some areas densely mapped and others lacking data, which does not necessarily indicate the absence of landslides. Southeast Alaska, for example, is underrepresented despite known hazards. Future efforts aim to improve statewide representation by integrating additional datasets such as the Tongass National Forest landslide inventory.Landslides were included as-is from original maps, meaning existing errors-whether from digitization, georeferencing, or classification-may persist. Because no field verification was conducted, the reliability of the data depends on the accuracy of the original geologic work. Coverage across the state is uneven, and the absence of mapped landslides in some areas does not imply their absence in reality. Users should consult original sources and use the data only at appropriate scales for regional or community-level analysis.The Alaska Landslide Inventory (ALI) contains notable gaps due to uneven mapping coverage and limitations in original source material. Some regions, such as Southeast Alaska, are underrepresented despite known landslide activity, largely because few existing publications included landslide data for those areas. Many landslides may remain undocumented simply because they have not yet been mapped. As a result, some areas show a high density of landslides while others show none, which does not necessarily reflect actual hazard levels. Future updates will aim to fill these gaps by incorporating additional datasets and expanding coverage to better represent landslide hazards statewide.The geographic locations in the Alaska Landslide Inventory (ALI) vary in accuracy due to differences in original mapping methods, scales, and georeferencing techniques. Landslides from existing maps were included without reinterpretation, meaning any positional errors from the original sources may persist. In some cases, older maps were georeferenced manually, which may have introduced localized inaccuracies. While some polygon boundaries were adjusted to better match aerial imagery, no field verification was conducted, so location accuracy ultimately depends on the quality of the original geologic work.Geodatabase deployment - To create the Alaska Landslide Inventory (ALI), DGGS geologists developed a geodatabase using schemas from regional and federal agencies, including the Washington Geological Survey, Oregon Department of Geology and Mineral Industries, and the U.S. Geological Survey. They created a data dictionary to define its structure and incorporated national mapping standards where possible. The team reviewed published geologic maps for landslide data, copied polygons from recent digital sources, and georeferenced older scanned maps for digitization. They standardized map unit abbreviations and maintained source records, used an ESRI ArcGIS Pro for database construction, and supplemented the inventory by identifying large unmapped landslides through news reports and aerial imagery.2025vectorAlaska Albers55.065.0-154.050.000coordinate pair0.00000000305360181585001630.0000000030536018158500163metersNAD83GRS 806378137298.257222101dds023_landslide_inventory_db_02_Sep_2025.gdb, dds023_landslide_inventory_layer_files, dds023_landslide_inventory_data_dictionary.xlsxThe dataset describes geographic features using mapped polygons classified by landslide movement type and annotated with metadata such as location, event date, and mapping method.DGGSlandslide_inventory_dblandslide_pointPoint representing each landslide deposit polygon, placed near initiation or centroidDGGSfree textdeposit_polygonPolygon outlining landslide deposit or full footprint including scarp, flank, and depositDGGSfree textflank_polygonPolygon tracing exposed flanks, sharing edges with scarp and deposit polygonsDGGSfree textscarp_polylinePolyline tracing head and internal scarps, including thaw slump headwalls; drawn clockwiseDGGSfree texttoe_polylinePolyline tracing historical toe of landslide movement downslope; drawn clockwiseDGGSfree textAlaska Division of Geological & Geophysical SurveysMetadata Managermailing and physical

3354 College Road

FairbanksAK99709-3707USA(907)451-5020(907)451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysFGDC Content Standard for Digital Geospatial MetadataFGDC-STD-001-1998If 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.https://dggs.alaska.gov/metadata/dggs.extdggs metadata extensions