Landslide hazard susceptibility mapping in Haines, Alaska, Report of Investigation 2024-8, provides a map and database of historical and prehistoric slope failures, maps of shallow and deep-seated landslide susceptibility, and a map of simulated debris flow runouts for the city and borough of Haines, Alaska. This work was prompted by the deadly Beach Road landslide that occurred on December 2, 2020, in Haines, Alaska, which highlights the significant safety and financial risks posed by slope failures to people and infrastructure. To better inform the Haines Borough of their potential landslide hazards and increase the city's hazard resiliency, the Alaska Division of Geological & Geophysical Surveys (DGGS) developed maps of historical and prehistorical slope failures, shallow landslide susceptibility, and modeled debris flow runouts. DGGS staff created a shallow landslide susceptibility map following protocols like those developed by the Oregon Department of Geology and Mineral Industries, which includes incorporating landslide inventory data, geotechnical soil properties, and lidar-derived topographic slope to calculate the Factor of Safety (FOS), which serves as a proxy for landslide susceptibility. Debris flow runout extents were generated using the model Laharz, which simulates runout extents based on catchment-specific physical parameters (e.g., hypothetical sediment volumes). Data from these analyses are collectively intended to depict locations where landslides are relatively more likely to occur or are relatively more likely to travel. The results provide important hazard information that can help guide planning and future risk investigations. The maps are not intended to predict slope failures and are site-specific; detailed investigations should be conducted before development in vulnerable areas. Results are for informational purposes and are not intended for legal, engineering, or surveying uses. These data and the interpretive maps and report are available from the DGGS website: http://doi.org/10.14509/31309.

The Alaska Division of Geological & Geophysical Surveys (DGGS) used lidar to produce digital terrain models (DTM), a digital surface model (DSM), and an intensity model for Homer, Alaska. Detailed bare earth elevation data for Homer were collected and processed for use in a landslide hazard resiliency project for the City of Homer. Data coverage includes neighboring Kachemak City. Lidar and Global Navigation Satellite System (GNSS) data were collected on June 3, 2019, and subsequently processed using TerraSolid and ArcGIS. The Alaska Division of Mining Land & Water (DMLW) Survey Section conducted a targeted Ground Control Survey for this project on June 19-20, 2019. These data are being released as a Raw Data File with an open end-user license. All files can be downloaded free of charge from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30591).

Coastal bluff stability assessment for Homer, Alaska, Report of Investigation 2022-5, evaluates the stability of coastal bluffs in Homer, Alaska, using aerial imagery and modern elevation data. We produce maps of historical shoreline change and an alongshore bluff instability hazard score. Shoreline change is calculated by comparing the bluff top and toe positions in historical and modern orthorectified aerial imagery. Since 1951, Homer's coastal bluffs have eroded at an average rate of -1.0 ft/yr (-0.29 m/yr). Key indicators of bluff instability are historical shoreline change rates, bluff slope and height, vegetation, existing erosion protection structures, and water drainage. Most of the Homer coastline has a low to medium bluff instability hazard score. These coastal hazard assessment products can guide decisions to reduce risk. These products are released as a DGGS publication component with an open end-user license. All files can be downloaded from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30908).

In this report, we evaluate potential tsunami hazards for southeastern Alaska communities of Elfin Cove, Gustavus, and Hoonah and numerically model the extent of inundation from tsunami waves generated by tectonic and landslide sources. We perform numerical modeling of historic tsunami events, such as the tsunami triggered by the 1964 Great Alaska Earthquake, and the tsunami waves generated by the recent 2011 Tohoku and 2012 Haida Gwaii earthquakes. Hypothetical tsunami scenarios include variations of the extended 1964 rupture, megathrust earthquakes in the Prince William Sound and Alaska Peninsula regions, and a Cascadia megathrust earthquake. Local underwater landslide events in Taylor Bay and Port Frederick, and a rockslide in Tidal Inlet are also considered as possible tsunamigenic scenarios. Numerical modeling results, combined with historical observations in the region, are intended to provide guidance to local emergency management in tsunami hazard assessment, evacuation planning, and public education for the reduction of future tsunami risk.

Alaska 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).

This report presents the findings of a geologic and geotechnical evaluation of a landslide at the Yukon River bridge (the E.L. Patton Bridge). The Yukon River bridge landslide occurred in fall 2012 between approximately 375 and 575 feet west of the bridge. Although there was no damage to the bridge foundation, the landslide's close proximity to the bridge and concerns over additional failures prompted multiple evaluations, including landslide documentation, drainage assessments, and geotechnical studies. This report was prepared to convey the general characteristics of the rock mass, characteristics of rock discontinuities, and the geomorphic expression of the 2012 landslide in the vicinity of the bridge. We determined that the fractured bedrock and steep slopes in the bridge vicinity are prone to slope failure. However, this assessment should be considered preliminary and should not be used to determine areas of potential future slope instabilities. A significant amount of additional exploration and slope stability analysis is required to fully understand the landslide hazard in the area of the bridge, as well as the potential for reactivation and/or expansion of the 2012 landslide into adjacent slopes.

Pluvials can have dramatic impacts on the shoreline bluffs of Lake Michigan due to increases in both shallow subsurface moisture conditions related to the prolonged wet weather pattern and wave erosion as the lake level rises. These changes can result in an increased frequency and magnitude of slope failures. During the most recent pluvial, the monthly average level of Lake Michigan rose 1.9 m from a record low in January 2013 to a near record high in June-July 2020. To assess the impacts on coastal bluffs from slope failures during the recent pluvial, an inventory of landslides was completed, including slope failures active during the early part of the pluvial, on the coastal bluffs of North Manitou Island, part of the Sleeping Bear Dunes National Lakeshore in Michigan. Landslides were mapped using high-resolution orthoimagery, collected in April 2012, and high-resolution topography derived from a LiDAR data set, collected in December 2014. This data release presents geographic information system (GIS) data, provided as line and polygon shapefiles (.shp), depicting landslides and related landforms and features. Polygon map data delineates the areas of deposits, source areas, and related landforms (such as alluvial fans and colluvial aprons). Scarps (such as headscarps and minor scarps) are presented as hachured line data. An attribute file is included providing a definition of the mapped units and a brief description of the approach used in the mapping.

Pluvials can have dramatic impacts on the shoreline bluffs of Lake Michigan due to increases in both shallow subsurface moisture conditions related to the prolonged wet weather pattern and wave erosion as the lake level rises. These changes can result in an increased frequency and magnitude of slope failures. During the most recent pluvial, the monthly average level of Lake Michigan rose 1.9 m from a record low in January 2013 to a near record high in June-July 2020. To assess the impacts on coastal bluffs from slope failures during the recent pluvial, an inventory of landslides was completed, including slope failures active during the early part of the pluvial, on the coastal bluffs of South Manitou Island, part of the Sleeping Bear Dunes National Lakeshore in Michigan. Landslides were mapped using high-resolution orthoimagery, collected in April 2012, and high-resolution topography derived from two LiDAR data sets, the first collected in December 2014 and the second collected between November 2015 and March 2016. This data release presents geographic information system (GIS) data, provided as line and polygon shapefiles (.shp), depicting landslides and related landforms and features. Polygon map data delineates the areas of deposits, source areas, and related landforms (such as alluvial fans and colluvial aprons). Scarps (such as headscarps and minor scarps) are presented as hachured line data. An attribute file is included providing a definition of the mapped units and a brief description of the approach used in the mapping.