| Online link | https://geo-nsdi.er.usgs.gov/metadata/map-i/2679/5HZ250.faq.html |
|---|---|
| Description | Probabilistic seismic hazard maps were prepared for Alaska portraying peak horizontal ground acceleration and horizontal spectral response acceleration for 0.2, 0.3, and 1.0 second periods with probabilities of exceedance of 10% in 50 years and 2% in 50 y |
| Originators | Wesson, Robert L.; Frankel, Arthur D.; Mueller, Charles S.; Harmsen, Stephen C.; and Rukstales, Kenneth S. |
Polygons in the coverage geo_net
| Label | Definition |
|---|---|
| GEOCODE | Type of geologic feature. Character, width 40. |
| NAM | Map unit name and associated symbol (ASCII character set does not include special symbol for Cambrian, requiring substitution of the letter "C" for the Cambrian symbol). Character, width 14. |
Arcs in geo_net coverage.
| Label | Definition |
|---|---|
| GEOCODE_L | Type of geologic feature. Character, width 40. |
| ACC | Accuracy of located contacts. Integer. |
Point features in geo_pnt coverage. These describe orientation of bedding in sedimentary rocks and orientation of eutaxitic layering in ash-flow tuffs.
| Label | Definition |
|---|---|
| GEOCODE | Type of surface for which orientation is given. Character, width 40. |
| STK | Measured strike in degrees. Integer. |
| DIP | Measured dip in degrees. Integer. NOTE: The info files give the azimuth for strike and the value for dip; the direction of dip is not readily apparent from the info files. The user should refer to the plotted graphic to determine direction of dip. |
| POS | Position of the bedding in sedimentary rocks or position of eutaxitic layering in ash-flow tuffs. Integer. |
| ACC | Accuracy, meaning whether the orientation of beds or the layering was measured or estimated. Integer. |
| CON | Integer indicating whether the bedding surface in sedimentary rocks is crumpled. |
Arcs in stru_net coverage. The direction of the arcs is significant in that it determines on which side the sawteeth or half circles are placed on the thrust and detachment faults. The sawteeth or half circles are on the upper plate. If these coverages are cleaned the arcs can 'flip' and the sawteeth or half circles will end up on the incorrect side of the fault. Please refer to the graphic file for correct placement of sawteeth or half circles.
| Label | Definition |
|---|---|
| GEOCODE | Type of feature. Character, width 40. |
| TYP | Type of fault or fold. Integer. |
| ACC | Accuracy of location of faults and folds. |
| DIR | Sense of relative movement on normal or oblique slip faults or to sense of oblique slip on thrust faults. |
| POS | Position of the axial surface of folds. |
Point features in stru_pnt coverage. These describe orientation of layering in metamorphic rocks.
| Label | Definition |
|---|---|
| GEOCODE | Type of surface for which orientation is given. Character, width 40. |
| STK | Measured strike of layering in metamorphic rocks, in degrees. Integer. |
| DIP | Measured dip of layering in metamorphic rocks, in degrees. Integer. NOTE: The info files give the azimuth for strike and the value for dip; the direction of dip is not readily apparent from the info files. The user should refer to the plotted graphic to determine direction of dip. |
| POS | Position of the layering in metamorphic rocks. Integer. |
| ACC | Accuracy, meaning whether the orientation of layering was measured or estimated. Integer. |
Lines of the data_net coverage form the quadrangle boundary and lines of section.
| Label | Definition |
|---|---|
| GEOCODE | Type of line. Character, width 40. |
| XTA | Identity of the cross section, if GEOCODE value is Xsection, blank otherwise. Character, width 30. |
Points in coverage data_pnt are locations for gravel pits, test wells, and springs.
| Label | Definition |
|---|---|
| GEOCODE | Type of feature. Character, width 40. |
Points in coverage pnt_sym locate arrows for faults and folds and U and D symbols for faults. (NOTE: On this map the "U" indicates the APPARENT upthrown side of a thrust fault and "D" the APPARENT downthrown side. Please refer to the graphic file for correct placement of sawteeth that indicate the upper plate.
| Label | Definition |
|---|---|
| TYP | Type of symbol. Character, width 10. NOTE: NORMAL/D and NORMAL/U as used here also include "U" and "D" on thrust faults.) |