Pahute Mesa--GIS Surface Effects Map Archive

Surface effects maps were produced for all 85 underground nuclear detonations conducted at the Pahute Mesa testing area of the Nevada Test Site between April 14, 1965 (Palanquin detonation, borehole U-20k, Area 20) and March 26, 1992 (Junction detonation, borehole U-19bg, Area 19). The Pahute Mesa Surface Effects Map Database contains digital reproductions of these original maps. The database is provided in both ArcGIS (v. 8.2) geodatabase format and ArcView (v. 3.2) shapefile format. When testing began at Pahute Mesa in 1965, detailed surface effects mapping at the Nevada Test Site had become routine. Thus, these surface effects maps show in considerable detail the collapse sinks, cracks, faults, and pressure ridges that were produced by the Pahute Mesa detonations. The combined (cumulative) length of surface effects in the database is 915.6 km (568.9 mi). In GIS digital format, the user can view all surface effects maps simultaneously, select and view the surface effects of one or more sites of interest, or view specific surface effects by area or site. Three map layers make up the database. They are: (1) the surface effects maps layer (pmse_n27f), (2) the bar symbols layer (pmse_bar_n27f), and (3) the ball symbols layer (pmse_ball_n27f). Additionally, an annotation layer, named "Ball_and_Bar_Labels," is contained in the geodatabase version of the database. This annotation layer automatically labels 880 of the 970 ball-and-bar symbols shown on these maps.

Post-detonation surface effects maps were produced for detonation sites using field and aerial-photo mapping techniques. The fractures produced by the detonations were mapped and reported on in many USGS Technical Letter reports. Features mapped included surface cracks (and fractures), collapse sinks, various types of fault movements, pressure ridges, and reactivated cracks. A final surface effects map, or "crack map" as they were often called, was prepared on stable-base mylar drafting film for use in USGS publications and reports. Ultimately, these maps were stored by the USGS in map files at the Denver Federal Center, Lakewood, Colorado. The digital reproduction and archiving of these maps was implemented as a means to not only store the original crack maps in a more permanent compact disc format, but to also make them accessible for scientific study and management activities.

1: This metadata file pertains to the three primary map layers that make up the database, as well as to all other area-wide and site-specific surface effects maps of the Pahute Mesa testing area.

2: The three map layers are named as follows:
pmse_n27f: polyline coverage containing the surface effects map features
pmse_bar_n27f: polyline coverage containing the bars of the bar-and-ball symbols
pmse_ball_n27f: point coverage containing the balls of the bar-and-ball symbols

3: The bar-and-ball symbols are used to illustrate vertical displacement on the down-thrown side of faults and vertically displaced cracks. The ball symbols (point coverage) contain an attribute field named OFFSET_CM. This field contains a numerical value that is used to label the fault symbols. The value indicates the amount of vertical offset (in centimeters) that was originally measured for these features.

The horizontal positional accuracy of the original surface effects maps is unknown. The digitizing accuracy of the vector conversion of these maps was maintained by on-screen digitizing at very large map scales (1:500 to 1:1,200) from the scanned and georeferenced original maps. A root mean square error (RMSE) of 0-3 meters (0-10 ft), as measured on the ground, was maintained during the preparation (scanning and georeferencing) of the original maps. No formal tests were performed.

NA