United States of America
U.S. Seismic Hazard Maps–Hawaii, Puerto Rico and the U.S. Virgin Islands, and Samoa and the Pacific Islands
Seismic hazard maps for Hawaii, Puerto Rico and the U.S. Virgin Islands, and Samoa and the Pacific Islands.
Vs30 Models and Data
The following resources are available for Vs30 (the time-averaged shear-wave velocity to 30 m depth) models and data.
Drivers and Impacts of North Pacific Climate Variability
Climate model forecasts indicate an increase in extreme hydrologic events, including floods and droughts, for California and the western U.S. in the future. To better understand what the consequences of this future change in climate may be, USGS scientists are studying the frequency, magnitude, and impacts of past hydroclimate variability and extremes in the region. This project produces well-...
Managed Areas
A delineation of managed areas (Federal, State, tribal, and military lands) from the USGS National Atlas was overlaid on the topographic change inventory. Note that this representation of managed lands is from a small-scale map source and does not include all Federal lands, while others are generalized. About 11 percent of the change polygons fall within the general boundaries of the managed...
Counties
Because so many other statistics and phenomena are reported and mapped on a county basis, they are a useful accounting unit with which to view the occurrences of topographic change. The counties that contain topographic change polygons are shown below. A total of 1,170 counties contain change polygons, which represents 37.6 percent of the counties in the conterminous United States. In some...
Ecoregions
Ecoregions have been developed and are being used to study the place dependency of environmental processes, including anthropogenic transformations of the land surface. Ecoregions are also the basis for reporting on the status and trends of land cover and land cover change. As a geographic framework that is useful for studying the response of the environment to human activities, ecoregions...
Watersheds
Because they are a natural partitioning of the land surface, watersheds have been used extensively to study and report on environmental conditions. As such, they provide another useful way to view and present the extent of topographic changes. The connectivity of watersheds may be an important condition when assessing the impacts of land surface transformations. For instance, an important...
States
The spatial distribution of the topographic change polygons across the states is shown in the figure below. Some noteworthy patterns seen on the map are a dense concentration of polygons in eastern Kentucky and southern West Virginia, a distinct cluster of polygons in northern Minnesota, several larger groups of polygons in Wyoming and southern Arizona, a concentration of polygons in the...
Landfills
Topographic change due to landfill operations has been observed based on some of the features delineated by the elevation differencing and thresholding process. The resulting altered landforms from landfills differ from other anthropogenic activities in that much of the deposited material is not rock and soil that had been previously excavated but man-made material that has been transported to...
Dam Construction
Hydrologic interference is a primary direct anthropogenic process, and dam construction is one type of interference that usually has obvious effects. Certainly, earth materials are moved during dam construction, but the larger impact is the inundation by the reservoir behind the dam.
Urban Development
The importance of urban development (including building construction and associated road construction) as a human geomorphic process has been recognized as a primary input for calculations of the total amount of material moved by humans. The topographic change polygon dataset includes many features that are the result of earth-moving operations for urban development.
Mining
According to the label assigned from the NLCD to each change polygon, mining is the predominant land use/land cover represented in the topographic change inventory. This is not surprising, as surface mining operations have been previously identified in the literature as the largest direct anthropogenic process in terms of the amount of material moved. Further evidence of the dominance of...