Folder
ROOT
_ScienceBase Catalog
__USGS Data Release Products
___Airborne Geophysical Surveys over the 2011 Mineral, Virginia, Earthquake Area
____Gravity data
The grids provided here are: "FAA_1000_UTM18N_NAD83.gxf" : Gravitational Free-air anomaly (mGal) with a 1-km half-wavelength grid filter "BA_267_1000_UTM18N_NAD83.gxf": the Bouguer anomaly (mGal) derived from the above free-air anomaly assuming a reference density of 2.67 g/m3. Grids are in the ASCII grid exchange format (.gxf). Header information provides the grid dimensions, separation, coordinates and map projection, and z-value range information. The grid values follow. The projected coordinate system used for all grids is UTM Zone 18N: Datum: NAD83 Base Latitude: 0.00 degrees Central Meridian: -75.00 degrees False Easting: 500,000 meters False Northing: 0 meters Scale factor at natural origin: 0.9996 Detailed...
Line data are presented as comma separated values (csv) with the following definitions: LINE Flight line number DIR Flight line direction, degrees clockwise from North DATE Year / Julian day TIME Time (UTM, 24-hour) hh:mm:ss LONG Longitude, WGS84 (degrees) LAT Latitude WGS84 (degrees) x_UTM18N Easting, UTM Zone 18N (meters) y_UTM18N Northing, UTM Zone 18N (meters) RALT Radar altimeter height (meters) LALT Laser altimeter height (meters) MSL GPS elevation, final (orthometric MSL - NAVD88 using GEOID09) (meters) DEM Digital elevation model (meters) FGRAVFL15 Levelled free air gravity, 15 s half-wavelength filter, 1,000 m half-wavelength...
Images provided here include: FAA_UTM18N_NAD83 (GeoTiff, KMZ): Free-air anomaly with a 1-km grid filter FAA_Cont1mGal_UTM18N_NAD83 (GeoTiff, KMZ): Free-air anomaly with a 1-km grid filter, 1 mGal contours FAA_Colorbar.png provides a colorbar key for these free-air anomaly images. BA_267_UTM18N_NAD83 (GeoTiff, KMZ): Bouguer anomaly derived from the free-air anomaly with a 1-km grid filter, assuming a uniform density of 2.67 g/m3 BA_267_Cont1mGal_UTM18N_NAD83 (GeoTiff, KMZ): Bouguer anomaly derived from the free-air anomaly with a 1-km grid filter, assuming a uniform density of 2.67 g/m3, 1 mGal contours BA_Colorbar.png provides a colorbar key for these Bouguer anomaly images. Images may be geo-registered...
