USGS Home
Contact USGS
Search USGS

Additional USGS Geoscience data can be found by geographic location or by publication series.

Hazard maps of the U.S.

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How should this data set be cited?

   U.S. Geological Survey, 1997, Hazard maps of the U.S.: U.S. Geological Survey Open-File Report 97-131 and 97-130.

   Online Links:

   • <ftp://hazards.cr.usgs.gov/hazmaps/gis/>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -125.00

   East_Bounding_Coordinate: -65.00

   North_Bounding_Coordinate: 49.40

   South_Bounding_Coordinate: 24.60

3. What does it look like?

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 1997

   Currentness_Reference: publication date

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: map

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?

      This is a vector data set. It contains the following vector data types (SDTS terminology):

      • GT-polygon composed of chains

   2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.1. Longitudes are given to the nearest 0.1. Latitude and longitude values are specified in decimal degrees.

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
      

7. How does the data set describe geographic features?

   US1HZ050.PAT

   1.0 second Spectral Acceleration with 10% Probability of Exceedance in 50 years (Source: OFR-97-0131)

   ACC_VAL

   Acceleration value in percent of gravity of the polygon. The polygon represents the range of acceleration values that are contained within its borders. The polygon is assigned the lowest value allowed within the polygon's borders. The range of values allowed within a polygon is controlled by the contours. (Source: OFR-97-0131)

   Range of values
   Minimum:	0
   Maximum:	100
   Units:	percent of gravity
   Resolution:	1

   VALLEY

   A topological indicator that tells whether the area contained within the polygon is a local minima (valley) or not. A value of "1" indicates the area is a local minima. (Source: OFR-97-0131)

   Value	Definition
   0	Not a local minima
   1	Location of local minima

   US1HZ050.AAT

   1.0 second Spectral Acceleration with 10% Probability of Exceedance in 50 years (same attributes as polygon coverage US1HZ0500.PAT) (Source: OFR-97-0131)

   US1HZ050.PAT

   Point coverage of 1.0 second Spectral Acceleration with 10% Probability of Exceedance in 50 years (same attributes as polygon coverage US1HZ050.PAT) (Source: OFR-97-0131)

   US1HZ100

   Polygon, arc, and point coverage of 1.0 seconds spectral acceleration with 5% probability of exceedance in 50 years. (same attributes as US1HZ050) (Source: OFR-97-0131)

   US1HZ250

   Polygon, arc, and line coverage of 1.0 seconds spectral acceleration with 2% probability of exceedance in 50 years. (same attributes as US1HZ050) (Source: OFR-97-0131)

   US3HZ050

   Polygon, arc, and point coverage of 0.3 second spectral acceleration with 10% probability of exceedance in 50 years (same attributes as US1HZ050) (Source: OFR-97-0131)

   US3HZ100

   Polygon, arc, and point coverage of 0.3 seconds spectral acceleration with 5% probability of exceedance in 50 years (same attributes as US1HZ050) (Source: OFR-97-0131)

   US3HZ250

   Polygon, arc, and point coverage of 0.3 seconds spectral acceleration with 2% probability of exceedance in 50 years (same attributes as US1HZ050) (Source: OFR-97-0131)

   US5HZ050

   Polygon, arc, and point coverage of 0.2 seconds spectral acceleration with 10% probability of exceedance in 50 years (same attributes as US1HZ050) (Source: OFR-97-0131)

   US5HZ100

   Polygon, arc, and point coverage of 0.2 seconds spectral acceleration with 5% probability of exceedance in 50 years. (same attributes as US1HZ050) (Source: OFR-97-0131)

   US5HZ250

   Polygon, arc, and point coverage of 0.2 second spectral accleration with 2% probability of exceedance in 50 years. (same attributes as US1HZ050) (Source: OFR-97-0131)

   USPGA050

   Polygon, arc, and point coverage of peak ground acceleration with 10% probability of exceedance in 50 years. (same attributes as US1HZ050) (Source: OFR-97-0131)

   USPGA100

   Polygon, arc, point coverage of peak ground acceleration with 5% probability of exceedence in 50 years (same attributes as US1HZ050) (Source: OFR-97-131)

   USPGA250

   Polygon, arc, and point coverage of peak ground acceleration with 2% probability of exceedance in 50 years (same attributes as US1HZ050) (Source: OFR-97-0131)

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • U.S. Geological Survey

2. Who also contributed to the data set?

3. To whom should users address questions about the data?
   Perkins, David M
   USGS-GEO-CRG-GHZ
   Mail Stop 966, USGS
   P.O. Box 25046
   Lakewood, CO 80225
   US
   

   303-273-8554 (voice)
   perkins@usgs.gov
   

Why was the data set created?

To provide to the public a digital hazard map database of the United States.

How was the data set created?

1. From what previous works were the data drawn?

2. How were the data generated, processed, and modified?

   (process 1 of 1)

3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?

2. How accurate are the geographic locations?

   Most of the gridded data for the United States is at a spacing of 0.1 degrees latitude and longitude. The higher resolution data available for California, Nevada, and part of Arizona and Utah were used for both the U.S. and Western U.S. maps. The gridded data for this area is at a spacing of 0.05 degrees latitude and longitude.

3. How accurate are the heights or depths?

4. Where are the gaps in the data? What is missing?

   Excludes Alaska, Hawaii, and Puerto Rico

5. How consistent are the relationships among the observations, including topology?

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none

Use_Constraints: none

1. Who distributes the data set? (Distributor 1 of 1)
   USGS Information Services
   Box 25286, Denver Federal Center
   Denver, Colorado 80255-0046
   USA
   

   1-888-ASK-USGS (voice)
   1-303-202-4695 (FAX)
   infoservices@usgs.gov
   

2. What's the catalog number I need to order this data set?

   US Geological Survey Open-File Report 97-0131

3. What legal disclaimers am I supposed to read?

   Although these data have been used by the U.S. Geological Survey, no warranty, expressed or implied is made by the USGS as to the accuracy of the data and related material nor shall the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS in connection therewith.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:

     Contours as polygons and arcs in format ArcInfo export (version 7.x)

     Network links:

     <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us1hz050.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us1hz100.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us1hz250.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us3hz050.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us3hz100.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us3hz250.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us5hz050.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us5hz100.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/us5hz250.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/uspga050.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/uspga100.e00.gz> <ftp://hazards.cr.usgs.gov/hazmaps/gis/export/uspga250.e00.gz>

   • Cost to order the data: none

Who wrote the metadata?

Dates:

Last modified: 01-Apr-2003

Metadata author:

Peter N Schweitzer
U.S. Geological Survey, ER
Geologist
Mail Stop 954
12201 Sunrise Valley Drive
Reston, VA 20192
USA

703-648-6533 (voice)
703-648-6252 (FAX)
pschweitzer@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)