The maps in this data release show active landslide structures in three areas along the north flank of the Slumgullion landslide. After the entire active part of the landslide was mapped in 1992 and 1993 (Fleming and others, 1999), we remapped these three smaller areas at roughly decadal intervals. Our goal was to learn what structures might persist and how they might change as heterogeneous landslide material of variable thickness passed through the areas. Together with the original 1999 map, these maps provide snapshots of the deformational features at converging and diverging margins of the landslide at four periods in about a 30-year time span (1992-2023).
During summer months in 2002, 2013, and 2023, we conducted 1:1000-scale mapping using a traditional technique of manually drawing lines on topographic base maps to represent the structures we observed in the field. There was generally a lapse of two or more years between acquisition of the topographic base data and the field mapping. Meters of landslide displacement during the lapse resulted in a mismatch between the topographic map and topography on the active landslide at the time of our fieldwork. When drawing features on the topographic base, we referenced fixed topographic features directly north of the active landslide’s strike-slip boundary to compensate for the mismatch. The data are recorded in Geographic Information System (GIS) files that contain the line styles used to portray and distinguish the different landslide structures. The files record the shapes and positions of the mapped landslide structures. An index of line styles used to portray mapped structures is shown in Figure 1. Topographic base maps used for the 2002, 2013, and 2023 structural maps were from 2000, 2011, and 2018, respectively. One-meter Digital Elevation Models (DEMs), contours, and shaded-relief maps from these three years are included in this data release. The 2000 DEM was created from 2 m contours of the landslide on July 31, 2000, as originally published in Messerich and Coe (2003). The 2011 DEM was created by the authors using a structure-from-motion photogrammetric method and 1:6000 scale aerial photos acquired on September 23, 2011. The 2018 DEM is lidar data collected between October 5, 2018 and September 24, 2019, with the original data available from the U.S. Geological Survey 3DEP Lidar Explorer (U.S. Geological Survey, 2024). The contour interval used for the 2000 DEM is 2 m. The contour interval used for the 2011 and 2018 DEM is 1 m. All GIS data are projected in the Universal Transverse Mercator (UTM) zone 13N cartesian coordinate system. Portable Document Format (PDF) files of the landslide structure maps of each area in 2002, 2013, and 2023, are also provided.
Figure 1. Line and polygon types used for landslide structures and features mapped at the Slumgullion landslide. References Fleming, R.W., Baum, R.L., and Giardino, Marco, 1999, Map and description of the active part of the Slumgullion Landslide, Hinsdale County, Colorado: U.S. Geological Survey Geologic Investigations Series Map I-2672 , scale 1:1,000, https://doi.org/10.3133/i2672 Messerich, J.A. and Coe, J.A., 2003, Topographic map of the active part of the Slumgullion landslide on July 31, 2000, Hinsdale County, Colorado: U.S. Geological Survey Open-File Report 03-144, 7 p., 1:1,000 scale map. http://pubs.usgs.gov/of/2003/ofr-03-144/ U.S. Geological Survey, 2024, 3DEP Lidar Explorer, data available at: http://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/1m/Projects/CO_Southwest_NRCS_2018_D18