Identification_Information:
  Citation:
    Citation_Information:
      Originator: U.S. Geological Survey
      Publication_Date: 200501
      Title: Significant United States Earthquakes, 1568-2004
      Publication_Information:
        Publication_Place: Reston, VA
        Publisher: National Atlas of the United States
      Online_Linkage: <http://nationalatlas.gov/atlasftp.html>

  Description:
    Abstract:
      This map layer contains the locations and attributes of significant, 
      historic earthquakes that caused deaths, property damage, and geological 
      effects, or were otherwise experienced by populations in the United 
      States, Puerto Rico, and U.S. Virgin Islands.  Included are earthquakes 
      located in the United States as well as some that occurred in adjacent 
      portions of Canada and Mexico.  The main sources for the data are 
      Seismicity of the United States, 1568-1989 and the Preliminary 
      Determination of Epicenters for 1990 to January 2004.  This is a 
      replacement for the June 1999 map layer.

    Purpose:
      These data are intended for geographic display and analysis at the 
      national level, and for large regional areas.  The data should be 
      displayed and analyzed at scales appropriate for 1:2,000,000-scale data.  
      No responsibility is assumed by the National Atlas of the United States 
      or the U.S. Geological Survey in the use of these data.  This data set is 
      intended for a mixed audience of specialists and non-specialists alike who 
      have a need for general, non-technical information about significant 
      United States earthquakes.

    Supplemental_Information:
      Provided with the downloadable files is a text file, 
      quksigx_references.txt, which contains the reference information for 
      earthquake magnitudes listed in the data. 

  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 15680101
        Ending_Date: 20040131
    Currentness_Reference: Ground condition

  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: As needed

  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: 143
      East_Bounding_Coordinate: -60
      North_Bounding_Coordinate: 65
      South_Bounding_Coordinate: 10
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: Environment
      Theme_Keyword: Geoscientific information

    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: Earthquakes
      Theme_Keyword: Seismic events
      Theme_Keyword: Magnitude
      Theme_Keyword: Body wave magnitude
      Theme_Keyword: Surface wave magnitude
      Theme_Keyword: Modified Mercalli Intensity Scale

    Place:
      Place_Keyword_Thesaurus:
        U.S. Department of Commerce, 1995, Countries, Dependencies, Areas of 
        Special Sovereignty, and Their Principal Administrative Divisions
        (Federal Information Processing Standard 10-4): Washington, D.C., 
        National Institute of Standards and Technology.
      Place_Keyword: United States
      Place_Keyword: Canada
      Place_Keyword: Mexico
    Place:
      Place_Keyword_Thesaurus: None
      Place_Keyword: USA
    Place:
      Place_Keyword_Thesaurus:
        U.S. Department of Commerce, 1987, Codes for the Identification of the 
        States, the District of Columbia and the Outlying Areas of The United
        States, and Associated Areas (Federal Processing Standard 5-2):  
        Washington, D.C., National Institute of Standards and Technology.
      Place_Keyword: Alabama
      Place_Keyword: Alaska
      Place_Keyword: Arizona
      Place_Keyword: Arkansas
      Place_Keyword: California
      Place_Keyword: Colorado
      Place_Keyword: Connecticut
      Place_Keyword: Delaware
      Place_Keyword: District of Columbia
      Place_Keyword: Florida
      Place_Keyword: Georgia
      Place_Keyword: Hawaii
      Place_Keyword: Idaho
      Place_Keyword: Illinois
      Place_Keyword: Indiana
      Place_Keyword: Iowa
      Place_Keyword: Kansas
      Place_Keyword: Kentucky
      Place_Keyword: Louisiana
      Place_Keyword: Maine
      Place_Keyword: Maryland
      Place_Keyword: Massachusetts
      Place_Keyword: Michigan
      Place_Keyword: Minnesota
      Place_Keyword: Mississippi
      Place_Keyword: Missouri
      Place_Keyword: Montana
      Place_Keyword: Nebraska
      Place_Keyword: Nevada
      Place_Keyword: New Hampshire
      Place_Keyword: New Jersey
      Place_Keyword: New Mexico
      Place_Keyword: New York
      Place_Keyword: North Carolina
      Place_Keyword: North Dakota
      Place_Keyword: Ohio
      Place_Keyword: Oklahoma
      Place_Keyword: Oregon
      Place_Keyword: Pennsylvania
      Place_Keyword: Rhode Island
      Place_Keyword: South Carolina
      Place_Keyword: South Dakota
      Place_Keyword: Tennessee
      Place_Keyword: Texas
      Place_Keyword: Utah
      Place_Keyword: Vermont
      Place_Keyword: Virginia
      Place_Keyword: Washington
      Place_Keyword: West Virginia
      Place_Keyword: Wisconsin
      Place_Keyword: Wyoming
      Place_Keyword: Puerto Rico
      Place_Keyword: Virgin Islands
      Place_Keyword: Virgin Islands of the United States
      Place_Keyword: Guam
      Place_Keyword: Northern Mariana Islands

  Access_Constraints: None
  Use_Constraints:
    None.  Acknowledgment of the National Atlas of the United States of America 
    and (or) the U.S. Geological Survey would be appreciated in products derived 
    from these data.

  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Margaret G. Hopper
        Contact_Organization: U.S. Geological Survey
      Contact_Address:
        Address_Type: Mailing address
        Address: MS966, Box 25046, Denver Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225-0046
        Country: USA
      Contact_Voice_Telephone: 303-273-8564
      Contact_Facsimile_Telephone: 303-273-8600
      Contact_Electronic_Mail_Address: hopper@usgs.gov

  Data_Set_Credit:
    The following U.S. Geological Survey scientists contributed to this 
    data set: A. Tarr, M. Hopper, J. Dewey, M. McKeever, and N. Trevor.

Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report: 
      The attribute table was manually checked for unreasonable attribute values 
      for depth and magnitude.
  Logical_Consistency_Report:
    No formal tests for logical consistency were performed on this data set, 
    principally because the data set contains attribute values that were arrived 
    at by either or both quantitative (i.e. instrumental) and qualitative (i.e.
    historical) methods.  Earthquakes that occurred prior to the introduction of 
    seismological instrumentation are known only from written records, such as 
    newspapers, books and journals, and diaries, which often may provide 
    contradictory information that has to be carefully examined and weighed.  As 
    seismographs became more common in the early 1960's, the origin time and 
    location were both more precisely and accurately determined but the 
    compilation and evaluation of intensity reports was, and still is, a process 
    that involves considerable subjectivity.  As a result, all attributes 
    associated with a given earthquake should be considered provisional and 
    subject to further revision based on acquisition of new information and use 
    of new analytical methods.
  Completeness_Report:
    This data set contains information on significant, historical earthquakes 
    that caused deaths, property damage, geological effects, or that were 
    experienced by populations in the epicentral area, for the United States, 
    Puerto Rico, the U.S. Virgin Islands, Guam, and the Northern Mariana 
    Islands.  These data are limited to the best estimates of earthquake 
    locations and to attributes such as magnitude and maximum intensity.

  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:
        100 meter is the nominal precision of the reported instrumentally 
        located coordinate values but accuracy is considerably less.  Accuracy 
        depends upon numerous factors including imprecision of the velocity 
        model of the earth, uneven distribution of seismic stations, and 
        imprecisions in the computational algorithm.  Following initial 
        proofreading of the input data file, a preliminary map of the locations 
        of the earthquakes was produced which was examined for gross errors in 
        spatial location.
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report:
        Although depths are reported to the nearest 1 kilometer, the accuracy is 
        considerably less owing to uncertainties in the velocity model of the 
        Earth, uneven distribution of seismic stations, and imprecisions in the 
        computational algorithm.

  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Stover, Carl W.
          Originator: Coffman, Jerry L.
          Publication_Date: 1993
          Title: Seismicity of the United States, 1568-1989 (Revised)
          Edition: 1
          Online_Linkage: <http://neic.usgs.gov/neis/epic/>
          Series_Information:
            Series_Name: Professional Paper
            Issue_Identification: 1527
          Publication_Information:
            Publication_Place: Washington, DC
            Publisher: U.S. Geological Survey
      Type_of_Source_Media: Paper
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1568
            Ending_Date: 1989
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: Seismicity of the United States
      Source_Contribution:
        Principal source of earthquake locations and attributes.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 200411 
          Title: Preliminary Determination of Epicenters (PDE)
          Online_Linkage: <http://neic.usgs.gov/neis/epic/>
      Type_of_Source_Media: Online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1973  
            Ending_Date: 20040131 
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: PDE
      Source_Contribution:
        Supplemental source of earthquake locations and attributes.

    Source_Information:        
      Source_Citation:
        Citation_Information:
          Originator: J.L. Coffman (ed.)
          Originator: C.A. von Hake (ed.)
          Originator: C.W. Stover (ed.)
          Publication_Date: 1982
          Title: Earthquake History of the United States
          Publication_Information:
            Publication_Place: Boulder, CO
            Publisher: 
              National Oceanic and Atmospheric Administration and U.S. 
              Geological Survey
      Type_of_Source_Media: Paper
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1638  
            Ending_Date: 1980 
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: EHUS1982
      Source_Contribution:
        Supplemental source of earthquake locations and attributes.

    Source_Information:        
      Source_Citation:
        Citation_Information:
          Originator: J.G. Tanner 
          Originator: J.B. Shepherd
          Publication_Date: 1997
          Title: 
            Project catalogue and seismic hazard maps, Seismic hazard in Latin 
            America and the Caribbean
          Online_Linkage: <http://midas.uprm.edu>
      Type_of_Source_Media: Online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1997
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: MIDAS-IPGH
      Source_Contribution:
        Supplemental source of earthquake locations and attributes.

    Process_Step:
      Process_Description:
        Data for the years 1568 to 1989, from Seismicity of the United States, 
        were combined with Preliminary Determination of Epicenters data for 1990 
        to 2004.  EHUS1982 and MIDAS-IPGH were used to compile information for 
        additional locations or for years not covered by the other sources.  The 
        resulting text file was loaded into ArcView and converted to a 
        shapefile.  Three records for Puerto Rico were dropped because they did 
        not include values for longitude and latitude.
      Source_Used_Citation_Abbreviation: Seismicity of the United States
      Source_Used_Citation_Abbreviation: PDE
      Source_Used_Citation_Abbreviation: EHUS1982
      Source_Used_Citation_Abbreviation: MIDAS-IPGH
      Process_Date: 200411

Spatial_Data_Organization_Information:
  Indirect_Spatial_Reference:
    U.S. Department of Commerce, 1987, Codes for the Identification of the 
    States, the District of Columbia and the Outlying Areas of The United 
    States, and Associated Areas (Federal Information Processing Standard 5-2):  
    Washington, D.C., National Institute of Standards and Technology.

  Direct_Spatial_Reference_Method: Point
  Point_and_Vector_Object_Information:
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Point
      Point_and_Vector_Object_Count: 5351

Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geographic:
      Latitude_Resolution: 0.000278
      Longitude_Resolution: 0.000278
      Geographic_Coordinate_Units: Decimal degrees
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: GRS1980
      Semi-major_Axis: 6378137.0
      Denominator_of_Flattening_Ratio: 298.257222

Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label:
        Significant United States Earthquakes (described by Quksigx020.dbf)
      Entity_Type_Definition:
        Earthquakes within or near to the United States that caused deaths, 
        property damage, or geological effects, or that were experienced by 
        populations in the epicentral area.  These events occurred between 1568 
        and January 2004.
      Entity_Type_Definition_Source: National Atlas of the United States
    Attribute:
      Attribute_Label: Shape
      Attribute_Definition: The representation of the entity in the data.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Point
          Enumerated_Domain_Value_Definition: 0-dimensional element
          Enumerated_Domain_Value_Definition_Source: ESRI GIS software
    Attribute:
      Attribute_Label: Quksigx020
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5387
    Attribute:
      Attribute_Label: Quake_id
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5390
    Attribute:
      Attribute_Label: Year
      Attribute_Definition: The year when the earthquake occurred.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1568
          Range_Domain_Maximum: 2004
    Attribute:
      Attribute_Label: Month
      Attribute_Definition: The month when the earthquake occurred.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 12
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999
          Enumerated_Domain_Value_Definition: The month of the event is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Day
      Attribute_Definition: The day when the earthquake occurred.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 31
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999
          Enumerated_Domain_Value_Definition: The day of the event is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Hour
      Attribute_Definition: 
        The GMT hour of the day when the earthquake occurred, on a 24-hour 
        clock.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 23
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999
          Enumerated_Domain_Value_Definition: The hour of the event is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Minute
      Attribute_Definition: 
        The minute of the hour when the earthquake occurred.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 59
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999
          Enumerated_Domain_Value_Definition: 
            The minute of the event is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Second
      Attribute_Definition: 
        The second of the minute when the earthquake occurred.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0.010
          Range_Domain_Maximum: 59.970
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999.000
          Enumerated_Domain_Value_Definition: 
            The second of the event is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Location
      Attribute_Definition:
        The name of the town, city, physical feature, or other describable 
        location near to the earthquake event.
      Attribute_Definition_Source: National Atlas of the United States   
      Attribute_Domain_Values:
        Unrepresentable_Domain:
          There is no predefined set of valid location names.
        Enumerated_Domain:
          Enumerated_Domain_Value: <Blank>
          Enumerated_Domain_Value_Definition: 
            No location description is available.
          Enumerated_Domain_Value_Definition_Source:
            National Atlas of the United States
    Attribute:
      Attribute_Label: Longitude
      Attribute_Definition: 
        The longitude of earthquake's epicenter in decimal degrees.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: -179.990
          Range_Domain_Maximum: 180.000
    Attribute:
      Attribute_Label: Latitude 
      Attribute_Definition: 
        The latitude of earthquake's epicenter in decimal degrees.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 12.686
          Range_Domain_Maximum: 68.689
    Attribute:
      Attribute_Label: Depth_km
      Attribute_Definition: 
        The depth of earthquake's focus in kilometers.  A value of 0 may 
        indicate the depth is unknown.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 274
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999
          Enumerated_Domain_Value_Definition: The depth is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Mb_gs
      Attribute_Definition: 
        The body wave magnitude of the earthquake as reported by the U.S.
        Geological Survey.  A body wave is a seismic wave that travels through 
        the Earth's inner layers. 
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 3.400
          Range_Domain_Maximum: 7.000
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999.000
          Enumerated_Domain_Value_Definition: 
            The body wave magnitude is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Ms_gs
      Attribute_Definition: 
        The surface wave magnitude of the earthquake as reported by the U.S.
        Geological Survey.  A surface wave is a seismic wave that travels along 
        the Earth's surface. 
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 3.100
          Range_Domain_Maximum: 8.500
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999.000
          Enumerated_Domain_Value_Definition: 
            The surface wave magnitude is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Other_mag1
      Attribute_Definition: 
        The magnitude of the earthquake as reported by the source identified in 
        Ref1.  The type of magnitude is described by the attribute Type1.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 2.080
          Range_Domain_Maximum: 9.240
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999.000
          Enumerated_Domain_Value_Definition: 
            No additional magnitude measurement is available.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Type1
      Attribute_Definition: 
        The type of magnitude recorded in the attribute Other_mag1, as defined 
        by the source identified in Ref1.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: FA
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is an estimated body wave 
            magnitude.  It is commonly computed from the felt area for 
            earthquakes which occurred before seismic instruments were in 
            general use.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: MD
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is based on the duration or coda 
            length of the earthquake vibration.  
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: ML
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the local magnitude, which is 
            also known as the original "Richter" magnitude.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: MW
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the moment magnitude.  It is 
            the measure of total energy released by an earthquake.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: Mn
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the local or regional 
            magnitude.  It is the body wave magnitude using the Lg wave.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: Ms
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the surface wave magnitude.  A 
            surface wave is a seismic wave that travels along the Earth's 
            surface.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: Mw
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the moment magnitude.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: UK
          Enumerated_Domain_Value_Definition: 
            The magnitude type for the magnitude given in Other_mag1 is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: mb
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the body wave magnitude.  A 
            body wave is a seismic wave that travels through the Earth's inner 
            layers.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: mbLg
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag1 is the local or regional 
            magnitude.  It is the body wave magnitude using the Lg wave.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: <Blank>
          Enumerated_Domain_Value_Definition: 
            The type of magnitude given in Other_mag1 is unknown.  The value 
            came from Coffman, Jerry L., and von Hake, Carl A., 1973, 
            Earthquake History of the United States:  U.S. Dept. of Commerce, 
            National Oceanic and Atmospheric Administration, Publication 41-1, 
            Revised Edition (Through 1970).
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Ref1
      Attribute_Definition: 
        A code identifying the source for the magnitude given in Other_mag1.  
        The list of sources is provided in the text file quksigx_references.txt.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Unrepresentable_Domain:
          There is no predefined set of valid reference codes.
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: <Blank>
          Enumerated_Domain_Value_Definition: 
            No reference information is available.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States

    Attribute:
      Attribute_Label: Other_mag2
      Attribute_Definition: 
        The magnitude of the earthquake as reported by the source identified in 
        Ref2.  The type of magnitude is described by the attribute Type2.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 2.900
          Range_Domain_Maximum: 8.400
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: -9999.000
          Enumerated_Domain_Value_Definition:
            No additional magnitude measurement is available.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Type2
      Attribute_Definition: 
        The type of magnitude recorded in the attribute Other_mag2, as defined 
        by the source identified in Ref2.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: FA
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is an estimated body wave 
            magnitude.  It is commonly computed from the felt area for 
            earthquakes which occurred before seismic instruments were in 
            general use.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: MD
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is based on the duration or coda 
            length of the earthquake vibration.  
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: ME
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the energy magnitude which is 
            the radiated energy of the earthquake.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: ML
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the local magnitude, which is 
            also known as the original "Richter" magnitude.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: MW
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the moment magnitude.  It is 
            the measure of total energy released by an earthquake.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: Mn
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the local or regional 
            magnitude.  It is the body wave magnitude using the Lg wave.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: Ms
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the surface wave magnitude.  A 
            surface wave is a seismic wave that travels along the Earth's 
            surface.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: Mw
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the moment magnitude.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: UK
          Enumerated_Domain_Value_Definition: 
            The magnitude type for the magnitude given in Other_mag2 is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: mb
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the body wave magnitude. A body 
            wave is a seismic wave that travels through the Earth's inner 
            layers.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: mbLg
          Enumerated_Domain_Value_Definition: 
            The magnitude given in Other_mag2 is the local or regional 
            magnitude.  It is the body wave magnitude using the Lg wave.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: <Blank>
          Enumerated_Domain_Value_Definition: 
            The type of magnitude given in Other_mag2 is unknown.  The value 
            came from Coffman, Jerry L., and von Hake, Carl A., 1973, 
            Earthquake History of the United States:  U.S. Dept. of Commerce, 
            National Oceanic and Atmospheric Administration, Publication 41-1, 
            Revised Edition (Through 1970).
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Ref2
      Attribute_Definition: 
        A code identifying the source for the magnitude given in Other_mag2.  
        The list of sources is provided in the text file quksigx_references.txt.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Unrepresentable_Domain:
          There is no predefined set of valid references.
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: <Blank>
          Enumerated_Domain_Value_Definition: 
            No reference information is available
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Mmio
      Attribute_Definition:
        Modified Mercalli Intensity (MMI), where the integer value represents 
        the Roman numeral designation of the MMI intensity.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: F
          Enumerated_Domain_Value_Definition:
            The earthquake was felt but no Modified Mercalli Intensity was 
            assigned.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
        Enumerated_Domain:
          Enumerated_Domain_Value: 2
          Enumerated_Domain_Value_Definition:
            An earthquake felt only by a few persons at rest, especially on 
            upper floors of buildings.  Delicately suspended objects may swing.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 3
          Enumerated_Domain_Value_Definition:
            An earthquake felt quite noticeably by persons indoors, especially 
            on upper floors of buildings.  Many people do not recognize it as an 
            earthquake.  Standing motor cars may rock slightly.  Vibration 
            similar to the passing of a truck.  Duration estimated in some 
            cases.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 4
          Enumerated_Domain_Value_Definition:
            An earthquake felt indoors by many, outdoors by few during the day.  
            At night, some awakened.  Dishes, windows, doors disturbed; walls 
            make cracking sound.  Sensation like heavy truck striking building.  
            Standing motor cars rocked noticeably.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 5
          Enumerated_Domain_Value_Definition:
            An earthquake felt by nearly everyone; many awakened.  Some dishes, 
            windows broken.  Unstable objects overturned.  Pendulum clocks may 
            stop.  
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 6
          Enumerated_Domain_Value_Definition:
            An earthquake felt by all; many frightened.  Some heavy furniture 
            moved; a few instances of fallen plaster.  Damage slight.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 7
          Enumerated_Domain_Value_Definition:
            An earthquake causing negligible damage in buildings of good design 
            and construction; slight to moderate in well-built ordinary 
            structures; considerable damage in poorly built or badly designed 
            structures; some chimneys broken.  Noticed by persons driving motor 
            cars.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 8
          Enumerated_Domain_Value_Definition:
            An earthquake causing slight damage in specially designed 
            structures; considerable in ordinary substantial buildings with 
            partial collapse.  Damage great in poorly built structures.  Fall of 
            chimneys, factory stacks, columns, monuments, walls.  Heavy 
            furniture overturned.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 9
          Enumerated_Domain_Value_Definition:
            An earthquake causing considerable damage in specially designed 
            structures; well-designed frame structures thrown out of plumb.  
            Damage great in substantial buildings, with partial collapse.  
            Buildings shifted off foundations.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 10
          Enumerated_Domain_Value_Definition:
            An earthquaking causing destruction of some well-built wooden 
            structures; most masonry and frame structures destroyed with 
            foundations.  Railroad rails bent.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 11
          Enumerated_Domain_Value_Definition:
            An earthquake where few, if any (masonry) structures remain 
            standing.  Bridges destroyed.  Railroad rails bent greatly.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
        Enumerated_Domain:
          Enumerated_Domain_Value: 12
          Enumerated_Domain_Value_Definition:
            An earthquake where damage is total.  Lines of sight and level 
            distorted.  Objects thrown into the air.
          Enumerated_Domain_Value_Definition_Source: 
            <http://neic.usgs.gov/neis/epic/mm_scale.html>
    Attribute:
      Attribute_Label: Felt_area
      Attribute_Definition: 
        The area, in square kilometers, in which the earthquake was felt. 
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: <1,000
          Range_Domain_Maximum: 5,000,000
      Attribute_Domain_Values:
        Enumerated_Domain: 
          Enumerated_Domain_Value: <Blank>
          Enumerated_Domain_Value_Definition: 
            The area in which the earthquake was felt is unknown.
          Enumerated_Domain_Value_Definition_Source: 
            National Atlas of the United States
    Attribute:
      Attribute_Label: Source
      Attribute_Definition: 
        The primary source of the earthquake information. 
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: EHUS1982
          Enumerated_Domain_Value_Definition:
            Coffman, J.L., von Hake, C.A., and Stover, C.W., 1982, Earthquake 
            History of the United States:  U.S. National Oceanic and Atmospheric 
            Administration and U.S. Geological Survey, Publication No. 41-1, 
            revised edition, [through 1980], 258p.		
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
        Enumerated_Domain:
          Enumerated_Domain_Value: MIDAS-IPGH
          Enumerated_Domain_Value_Definition:
            Tanner, J.G. and Shepherd, J.B., 1997, Project catalogue and seismic 
            hazard maps, Seismic hazard in Latin America and the Caribbean:  
            Panamerican Institute of Geography and History, v. 1, 143 p.	
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
        Enumerated_Domain:
          Enumerated_Domain_Value: PDE
          Enumerated_Domain_Value_Definition:
            Preliminary Determination of Epicenters, a list of earthquakes 
            located by the National Earthquake Information Center of the U.S. 
            Geological Survey and its predecessors in the U.S. Coast and 
            Geodetic Survey, the National Oceanic Survey, and the Environmental 
            Research Laboratories of the Department of Commerce.  The PDE is 
            comprised of final hypocenter and magnitude computations by the USGS 
            NEIC published in monthly lists several months after the events.	
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
        Enumerated_Domain:
          Enumerated_Domain_Value: SUS
          Enumerated_Domain_Value_Definition:
            Stover, Carl W., and Coffman, Jerry L., 1993a, Seismicity of the 
            United States, 1568-1989 (Revised):  U.S. Geological Survey 
            Professional Paper 1527, 418 p.		
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey

Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: 
          Earth Science Information Center, U.S. Geological Survey
      Contact_Address:
        Address_Type: Mailing address
        Address: 507 National Center
        City: Reston
        State_or_Province: VA
        Postal_Code: 20192
      Contact_Voice_Telephone: 1-888-ASK-USGS (1-888-275-8747)
      Contact_Voice_Telephone: 703-648-5920
      Contact_Instructions: 
        In addition to the address above there are other ESIC offices throughout 
        the country.  A full list of these offices is at 
        <http://geography.usgs.gov/esic/esic_index.html>.

  Distribution_Liability: 
    Although these data have been processed successfully on a computer system at 
    the U.S. Geological Survey, no warranty expressed or implied is made by the 
    U.S. Geological Survey regarding the utility of the data on any other 
    system, nor shall the act of distribution constitute any such warranty.  No 
    responsibility is assumed by the U.S. Geological Survey in the use of these 
    data.  

  Standard_Order_Process: 
    Digital_Form: 
      Digital_Transfer_Information:
        Format_Name: ESRI Shapefile 
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: <http://nationalatlas.gov/atlasftp.html>
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format: tar
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: SDTS
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: <http://nationalatlas.gov/atlasftp.html>
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format: tar
    Fees:
      There is no charge for the online option.  For National Atlas files 
      ordered on CD-ROM there is a base price of $45.00 per disc, a handling fee 
      of $5.00, and a per-file charge based on file size.  The charge for files 
      less than 10 megabytes in size is $1.00.  The charge for files that range 
      in size from 10 to 150 megabytes is $7.50.  The charge for files of 150 
      megabytes or larger is $15.00.  The charge is $1.00 for the Significant 
      United States Earthquakes 1568-2004 data set.
    Ordering_Instructions:
      To order files on CD-ROM, please see
      <http://nationalatlas.gov/atlasftp.html#q12>.

Metadata_Reference_Information:
  Metadata_Date: 20050112
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Gita Urban-Mathieux
        Contact_Organization: National Atlas of the United States
      Contact_Address:
        Address_Type: Mailing address
        Address: 12201 Sunrise Valley Dr
        Address: MS 561
        City: Reston
        State_or_Province: VA
        Postal_Code: 20192
      Contact_Voice_Telephone: 703-648-5175
      Contact_Electronic_Mail_Address: atlasmail@usgs.gov
  Metadata_Standard_Name:
    FGDC Content Standards for Digital Geospatial Metadata 
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Security_Information: 
    Metadata_Security_Classification_System: None
    Metadata_Security_Classification: Unclassified
    Metadata_Security_Handling_Description: None
