b3887528-a4f1-45ed-a841-9e41138e2e2e_source eng; USA utf8 dataset Simone Montayne Alaska Division of Geological & Geophysical Surveys Metadata Manager (907)451-5020 (907)451-5050 3354 College Road Fairbanks AK 99709-3707 USA dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays pointOfContact 2024-04-05 ISO 19115 Geographic Information - Metadata ISO 19115:2003/Cor.1:2006(E) Landslide hazard susceptibility mapping in Homer, Alaska 2024-01-01 publication Alaska Division of Geological & Geophysical Surveys Fairbanks Alaska, United States publisher Salisbury, J.B. originator https://doi.org/10.14509/31155 GEODATABASE, RASTER Report of Investigation RI 2024-3 21 p., 3 sheets Landslide hazard susceptibility mapping in Homer, Alaska, Report of Investigation 2024-3, 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 of Homer, Alaska and nearby populated areas including Kachemak City and Millers Landing. The landslide inventory map integrates existing maps of landslides caused by the 1964 Great Alaska Earthquake and newly mapped slope failures identified in sequences of aerial photos since 1950 and high-resolution light detection and ranging (lidar) data collected for this project. The Alaska Division of Geological & Geophysical Surveys (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/10.14509/31155. This study provides a regional evaluation of landslide hazards in and around the City of Homer. The study aims to help the community better understand landslide hazards, inform mitigation efforts, guide future development activities, and protect public safety. DGGS collected and processed lidar for use in this landslide hazard resiliency project for the City of Homer, funded by the Federal Emergency Management Agency (FEMA) through Cooperating Technical Partnership (CTP) with the City of Homer and DGGS under federal grant number CTP EMS-2018- CA-00016-S01. DGGS thanks the Homer Planning Commission for guidance throughout the multi-year project and Jonathan Godt, Rich Buzard, and Bretwood Higman for constructive reviews that significantly improved this manuscript. We also thank Amy Macpherson for GIS support and Kristen Janssen for designing the report layout. completed Alaska Division of Geological & Geophysical Surveys Metadata Manager (907)451-5020 (907)451-5050 3354 College Road Fairbanks AK 99709-3707 USA dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays 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. pointOfContact notPlanned Coastal Coastal and River Colluvium DGGS Debris Avalanche Debris Flow Debris Flow Deposit Earthquake Related Slope Failure Engineering Engineering Geology Environment Environmental Geologic Geologic Hazards Geological Process Geology Geomorphology Geotechnical Hazards Hydrology and Surficial Geology Landslide LiDAR Modeling Raster Image Slope Slope Instability Surface Surface Water Surficial Surficial Geology theme Alaska Division of Geological & Geophysical Surveys Bear Canyon Beluga Lake Bidarki Creek Bluff Point Bridge Creek Bridge Creek Reservoir City of Homer City of Kachemak Coal Point Cook Inlet Crossman Ridge Diamond Creek Diamond Gulch Diamond Ridge Homer Homer Spit Kachemak Bay Kachemak City Lampert Lake Mud Bay Neilson Canyon Palmer Creek Sterling Highway Twitter Creek Waterman Canyon Woodard Canyon place Alaska Division of Geological & Geophysical Surveys 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. otherRestrictions 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. otherRestrictions 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). Photogrammetry-derived historical orthoimagery for Homer, Alaska from 1951, 1952, 1964, and 1985 2021-01-01 publication Alaska Division of Geological & Geophysical Surveys Fairbanks Alaska, United States publisher Buzard, R.M. originator https://doi.org/10.14509/30824 Raw Data File RDF 2021-21 10 p crossReference Coastal bluff stability assessment for Homer, Alaska 2022-01-01 publication Alaska Division of Geological & Geophysical Surveys Fairbanks Alaska, United States publisher Buzard, R.M. originator Overbeck, J.R. originator https://doi.org/10.14509/30908 Report of Investigation RI 2022-5 22 p., 2 sheets, scale 1:50,000 crossReference Bluff Point landslide, a massive ancient rock failure near Homer, Alaska 1978-01-01 publication Alaska Division of Geological & Geophysical Surveys Fairbanks Alaska, United States publisher Reger, R.D. originator https://doi.org/10.14509/409 Geologic Report GR 61B p. 5-9 crossReference Lidar-derived elevation models for Homer, Alaska 2021-01-01 publication Alaska Division of Geological & Geophysical Surveys Fairbanks Alaska, United States publisher Salisbury, J.B. originator Daanen, R.P. originator Herbst, A.M. originator https://doi.org/10.14509/30591 Raw Data File RDF 2021-2 6 p crossReference Updated tsunami inundation maps for Homer and Seldovia, Alaska 2019-01-01 publication Alaska Division of Geological & Geophysical Surveys Fairbanks Alaska, United States publisher Suleimani, E.N. originator Nicolsky, D.J. originator Salisbury, J.B. originator https://doi.org/10.14509/30095 Report of Investigation RI 2018-5 v. 2 97 p., 11 sheets crossReference grid eng; USA geoscientificInformation -151.732814 -151.372943 59.598718 59.709401 1964-01-01 2023-01-01 >scarps_lidar: Feature class containing landslide head scarp lines identified and digitized based on geomorphological characteristics in the high-resolution 2019 lidar data. >deposits_lidar: Feature class containing polygons outlining the extent of landslide deposits identified in the high-resolution 2019 lidar data. >deposits_photo: Slope failures identified in georeferenced aerial images. >runouts: Feature dataset collection of feature classes that provide categorical volume and dimensions of modeled hypothetical debris flow runouts from steep catchments in the Homer area. Runout zones are computed using LaharZ (Iverson and others, 1998; Schilling, 1998), and debris flow material characteristics are from Griswold and Iverson (2008). Volumes for runout zone modeling were estimated per catchment based on percentages (5, 10, 25 percent) of the total volume of topsoil in the catchment, as well as the percentage of catchment identified as having sustained slope failure in the historical period. Estimated points beyond which sediments are deposited are based on the geomorphological characteristics of each catchment. >FOS-5m: Raster image data model of the relationship between shear forces acting to move material downslope and forces acting to resist downslope movement. This model was used as a proxy for shallow landslide susceptibility. true geodatabase, raster unknown Alaska Division of Geological & Geophysical Surveys Metadata Manager (907)451-5020 (907)451-5050 3354 College Road Fairbanks AK 99709-3707 USA dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays 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. distributor Contact DGGS for current pricing Free download https://doi.org/10.14509/31155 geodatabase, raster digital data information dataset Horizontal Positional Accuracy Report DGGS used lidar point cloud data to produce a high-resolution (1.6 ft [0.5 m]) digital terrain model (DTM) and a digital surface model (DSM) for Homer (Salisbury and others, 2021). The DTM, also known as a bare-earth elevation model, was essential for identifying landslide geomorphology beneath dense vegetation, confirming evidence of landslide activity identified in aerial photograph sequences, making FOS calculations, and modeling potential debris flow runouts. The positional accuracy the slope failure inventory, factor of safety, debris flow runout models were developed using the best available data; however, there are inherent limitations to the calculated and interpreted feature extents. The accompanying report provides a complete discussion of specific limitations and potential sources of error. This data release is complete. This data release is complete. Not applicable This lineage was generated by the FGDC CSDGM to 19139 transformation Lidar Acquisition and Processing - DGGS used lidar point cloud data to produce a high-resolution (1.6 ft [0.5 m]) digital terrain model (DTM) and a digital surface model (DSM) for Homer (Salisbury and others, 2021). The DTM, also known as a bare-earth elevation model, was essential for identifying landslide geomorphology beneath dense vegetation, confirming evidence of landslide activity identified in aerial photograph sequences, making FOS calculations, and modeling potential debris flow runouts. 2019-01-01T00:00:00 Landslide Inventory - The comprehensive landslide inventory presented here spans 1952-2019 and was generated by (1) collecting and organizing existing information about previously identified landslides; (2) obtaining, georeferencing, and analyzing sets of aerial photographs since 1952; (3) acquiring, processing, and analyzing high-resolution lidar elevation data; (4) compiling all landslide information into a geodatabase; and (5) generating a landslide inventory map. 2021-01-01T00:00:00 Shallow Landslide Susceptibility - We estimated the FOS for shallow landslides, or earthflows, that are approximately the thickness of the mapped soil column (~5 ft [1.25 m] or less, USDA NRCS, 2005). Data were processed using methods described in the accompanying report. 2021-01-01T00:00:00 Deep-Seated Landslide Susceptibility - Deep-seated landslides involve the failure of materials, as the name implies, several tens of feet below layers of active soil and the uppermost weathered bedrock in an area. We estimated the FOS for Deep-seated landslides using methods described in the accompanying report. 2021-01-01T00:00:00 Debris Flow Runout Modeling - We used LaharZ, a computer model developed by Schilling (1998) for the U.S. Geological Survey, to simulate the behavior and forecast areas likely to be inundated by hypothetical future debris flow events. For all hypothetical runouts, we used ArcGIS Pro focal statistics and conditional tools to smooth the results. 2021-01-01T00:00:00 otherRestrictions Metadata Use Constraints: 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. unknown This metadata was automatically generated from the FGDC Content Standard for Digital Geospatial Metadata standard (version FGDC-STD-001-1998) using the 2019-08-12T11:11:00 version of the FGDC CSDGM to ISO 19139 transform. Simone Montayne Alaska Division of Geological & Geophysical Surveys Metadata Manager (907)451-5020 (907)451-5050 3354 College Road Fairbanks AK 99709-3707 USA dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays pointOfContact