National Atlas of the United States Seismic Events: Map Layer Description File This map layer includes a selection of seismic events above 4.0 magnitude in and near the United States for the years 1973-1998. The Seismic Events map layer was compiled by the U.S. Geological Survey from a database maintained by its National Earthquake Information Center. The magnitude of the earthquake is a logarithmic measure of its "size." This is commonly referred to as the "Richter scale". Download this map layer in Shapefile format. Download this map layer in SDTS format. -------------------------------------------------------------------------------- Metadata What follows is very detailed technical information about this map layer. This is often called metadata. Metadata (or "data about data") describe the content, quality, condition, and other characteristics of data. Metadata are used to organize and maintain investments in data, to provide information to data catalogs and clearinghouses, and to aid data transfers. The Federal Geographic Data Committee (FGDC) publishes the Content Standard for Digital Geospatial Metadata. Many organizations within and outside of the federal government have adopted the FGDC metadata standard and are using automated indexing and serving mechanisms to provide access to their holdings through the Internet. Visit the FGDC Clearinghouse to learn more about how metadata is used in clearinghouses and to search for other data sets. Identification Information Data Quality Information Spatial Data Organization Information Spatial Reference Information Entity and Attribute Information Distribution Information Metadata Reference Information Identification Information: Citation: Citation_Information: Originator: U.S. Geological Survey (USGS) Publication_Date: 1996 Title: Earthquakes Publication_Information: Publication_Place: Reston, Virginia Publisher: U.S. Geological Survey Description: Abstract: This data set includes a selection of seismic events above 4.0 magnitude in and near the United States for the years 1973-1998. Purpose: The digital data sets are used to create electronic and hard copy maps that depict various aspects of the nation. The data can be used to conduct geographic analysis on national and large regional scales. The digital data will provide a basis from which future revisions of the atlas can be derived. Supplemental_Information: Revisions: 1) 6/29/98 - Corrected ellipsoid name from WGS84 to GRS1980 and changed flattening ratio. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1998 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: Irregular Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: 172.0 East_Bounding_Coordinate: -66.0 North_Bounding_Coordinate: 72.0 South_Bounding_Coordinate: 18.0 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: seismic Theme_Keyword: earthquakes 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 (FIPS) 10-4): Washington, D.C., National Institute of Standards and Technology. Place_Keyword: United States Access_Constraints: None Use_Constraints: None. Acknowledgment of the National Earthquake Information Center (NEIC) would be appreciated in products derived from these data. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Bruce Wright Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 521 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Contact_Voice_Telephone: 703-648-4528 Contact_Electronic_Mail_Address: bwright@usgs.gov Data Quality Information: Logical_Consistency_Report: No tests for logical consistency were performed on this data set. Completeness_Report: This data set includes all seismic events in and near the United States. No tests for completeness were performed on this data set. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: National Earthquake Information Center (NEIC), USGS-Geologic Division Publication_Date: 1998 Title: Earthquake data base Publication_Information: Publication_Place: Golden, CO Publisher: USGS Type_of_Source_Media: online Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1973 Ending_Date: 1998 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: n/a Source_Contribution: spatial and attribute information Process_Step: Process_Description: The data were extracted from the NEIC Earthquake Search WWW site at: The data were then loaded into an INFO database. Latitude and Longitude values were written to an external file and used as input to the ARC/INFO command GENERATE to create a point coverage. The remaining attributes were joined to the data using the command JOINITEM. A bounding rectangle was used to isolate just those earthquakes located in the area of interest, standard tics were added and point topology was build. A spot check was conducted to validate that the proper attributes were associated with the earthquake locations. Process_Date: 1998 Spatial Data Organization Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Point Point_and_Vector_Object_Count: 26867 Spatial Reference Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.01 Longitude_Resolution: 0.01 Geographic_Coordinate_Units: Decimal Degrees Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: GRS1980 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257222 Entity and Attribute Information: Detailed_Description: Entity_Type: Entity_Type_Label: QUAKESX020.PAT Entity_Type_Definition: Point attribute table Entity_Type_Definition_Source: ARC/INFO Attribute: Attribute_Label: AREA Attribute_Definition: Point Attribute_Definition_Source: Computed Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 0.0 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: PERIMETER Attribute_Definition: Point Attribute_Definition_Source: Computed Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 0.0 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: QUAKESX020# Attribute_Definition: Internal feature number Attribute_Definition_Source: Computed Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: QUAKESX020-ID Attribute_Definition: User-assigned feature number Attribute_Definition_Source: User-defined Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Integer Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: CATALOG_SRC Attribute_Definition: Contributing source of earthquake data Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: PDE = Contributed by USGS NEIC, Preliminary Determination of Epicenters - Monthly Listing Enumerated_Domain_Value_Definition: Contributed by USGS NEIC, Preliminary Determination of Epicenters - Monthly Listing Enumerated_Domain_Value_Definition_Source: NEIC Attribute: Attribute_Label: YEAR Attribute_Definition: Year of the event Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 1973-1998 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: NEIC Attribute: Attribute_Label: MONTH Attribute_Definition: Month of the event Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 1-12 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: DAY Attribute_Definition: Day of the event Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 1-31 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: ORIGIN_TIME Attribute_Definition: Time of the event in Universal Time Coordinated (UTC) in hours, minutes, seconds, and decimal seconds expressed as a single real number. Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 000000.0 - 235959.9 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute_Units_of_Measure: decimal degrees Attribute: Attribute_Label: LAT Attribute_Definition: Latitude of earthquake Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: 0-90 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute_Units_of_Measure: decimal degrees Attribute: Attribute_Label: LON Attribute_Definition: Longitude of earthquake Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: -180 to 0 and 155 to 180 Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: n/a Attribute: Attribute_Label: DEPTH Attribute_Definition: Depth of earthquake in kilometers Attribute_Definition_Source: NEIC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 634 Attribute_Units_of_Measure: Kilometers (rounded up to nearest) Attribute: Attribute_Label: MAGNITUDE Attribute_Definition: Magnitude of the earthquake. It is a logarithmic measure of the "size" of an earthquake. Commonly referred to as the "Richter scale". Attribute_Definition_Source: NEIC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 4.0 Range_Domain_Maximum: 8.10 Attribute: Attribute_Label: MAG_SCALE Attribute_Definition: Magnitude scale Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Parameters that apply to the magnitude value. See NEIC WWW site for more information: Enumerated_Domain_Value_Definition_Source: NEIC Attribute: Attribute_Label: MAG_SOURCE Attribute_Definition: Two and three letter acronyms of the source of the magnitude data. See the NEIC WWW site for more information ( Attribute_Definition_Source: NEIC Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Various two and three letter acronyms Enumerated_Domain_Value_Definition: n/a Enumerated_Domain_Value_Definition_Source: National Earthquake Information Center Overview_Description: Entity_and_Attribute_Overview: The point attribute table: Column Item Name Width Output Type N. Dec. 1 AREA 4 12 F 3 5 PERIMETER 4 12 F 3 9 QUAKESX020# 4 5 B - 13 QUAKESX020-ID 4 5 B - 17 CATALOG_SRC 3 3 C - 20 YEAR 4 4 I - 24 MONTH 2 2 I - 26 DAY 2 2 I - 28 ORIGIN_TIME 4 12 F 2 33 LAT 4 12 F 2 36 LON 4 12 F 2 40 DEPTH 4 4 I - 44 MAGNITUDE 4 12 F 2 48 MAG_SCALE 2 2 C - 50 MAG_SOURCE 2 2 C - Entity_and_Attribute_Detail_Citation: n/a Distribution Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Bruce Wright Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 521 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Contact_Voice_Telephone: 703-648-4528 Contact_Electronic_Mail_Address: bwright@usgs.gov 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 USGS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Metadata Reference Information: Metadata_Date: 19980514 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Bruce Wright Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 521 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Contact_Voice_Telephone: 703-648-4528 Contact_Electronic_Mail_Address: bwright@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: 19940608 Metadata_Security_Information: Metadata_Security_Classification_System: None Metadata_Security_Classification: Unclassified Metadata_Security_Handling_Description: None -------------------------------------------------------------------------------- U.S. Geological Survey National Atlas of the United States and The National Atlas of the United States of America are trademarks of the United States Geological Survey. URL: http://www.nationalatlas.gov/quakesmt.html Public access to these map layers is provided by the EROS Data Center Comments and feedback: atlasmail Last modification: 02JUN99 bum