2008 NSHM Gridded Data
These files contain space-delimited, rectangular gridded data over the Conterminous 48 States in 0.05 degree increments in longitude (x-value) and latitude (y-value), starting from a northwest point at 50°N 125°W and ending at a southeast point at 24.6°N 65°W. Values are ordered starting in the northwest, proceeding across longitude values keeping the latitude value the same until the eastern-most point for that latitude value is reached, then wrapping to next latitude value and restarting with the western-most longitude value. This processes is repeated until the aforementioned grid is filled.
Download Data Files
- Hazard Curves 34Mb Each
- 10% in 50 Years 3.2Mb Each
- 5% in 50 Years 3.2Mb Each
- 2% in 50 Years 3.2Mb Each
Data File Formats
“Hazard Curves” Files
These files contain hazard curves for the gridded geographic points as described above. All the hazard curves in the file share the same set of x-values (intensity measure levels). The first two lines tell you that these files contain data for both the western and central and eastern United States. The third line specifies the spectral period (in seconds) used when computing the hazard curves for the file. The following lines (with 1 value per line) contain the x-values (intensity measure levels) for all the curves in the file. Subsequent lines contain hazard curves with a single geographic point per line. The first two values specify the longitude and latitude (respectively) for the curve while subsequent values (on that same line) contain mean annual frequencies of exceedance ordered corresponding to the x-values at the top of the file.
“X% in 50 Years” Files
These files contain ground motion values for the gridded geographic points as described above. The ground motion units are in g where 1g = 980.5 cm/s/s and are defined for the B/C boundary (Vs30 = 760 m/s). Data contained in these files specify a single geographic point per line starting with longitude and latitude values (respectively), with the third and final value of each line specifying the ground motion for that geographic point.
