Earthquake Search Documentation
Earthquake Data Base
This data base provides information on earthquakes from 2100 B.C. to the present. The data base contains earthquakes with known magnitude values between 0.1 and 9.9. Earthquakes that have no computed magnitude values are also included in the data base. Users of micro-earthquake data (magnitude less than or equal to 0.0) should contact institutions that operate seismograph networks in their area of interest. In reality, there are very few events with magnitude less than 2.0 in the data base.
Search Parameter Selection
Output Format
Expanded FormatThe Expanded Format contains a list of earthquakes along with explanatory header lines of text. The file also lists a summary of the search parameters. Line length is 132 characters.
Screen Format
The Screen Format contains a list of earthquakes
along with explanatory header lines of text.
The file also lists a summary of the search parameters.
Line length is 80 characters.
It is an abbreviated form of the Expanded
Format.
Compressed Format
The Compressed Format is designed for use as input for
further computer processing. Extraneous spaces are omitted.
Line length is 116 characters.
Search Area
Global Search
The Global Search selects all earthquakes regardless
of their geographic location.
Rectangular Area Search
The Rectangular Area Search selects earthquakes that
are located within a user-defined rectangular grid.
Choose the search area by entering the top and bottom
latitude and the right and left longitude of the rectangle.
Enter the coordinates in decimal degrees. North latitudes
and east longitudes are input as positive values.
South latitudes and west longitudes are input as
negative values.
Note: The search will not not span more than 180 degrees of
longitude.
Circular Area Search
The Circular Area Search selects earthquakes that are
located within a circular area defined by a center point
and a radius.
Choose the search area by entering the center latitude
and longitude and radius.
Enter the coordinates in decimal degrees. North latitudes
and east longitudes are input as positive values.
South latitudes and west longitudes are input as
negative values. Enter the radius in kilometers.
Data Base
Contributing source, or authority.
NOTE: Hypocenters and magnitudes of some earthquakes may differ from catalog to catalog depending on the earthquake catalog from which the information is taken. See Catalog Source.
To select earthquakes that occurred in the last few weeks,
select USGS/NEIC (PDE-Q) Most Recent Events.
Optional Search Parameters
Date
Setting the year, month and day are optional.
To retrieve all dates, leave these field blank.
To search for one for more complete years,
set the Starting and Ending Year values,
leaving the Starting and Ending Month and Day blank.
Use negative numbers to specify years in B.C. time;
otherwise, the date is interpreted as A.D.
Note: All dates in the database are in Coordindated Universal
Time (UTC).
Magnitude
Setting the magnitude range is optional.
To retrieve all earthquakes, including those
without assigned magnitudes, leave these fields blank.
The data base contains earthquakes with known magnitude values
from 0.1 to 9.9.
To restrict
the data selection to a specific magnitude range,
set the Minimum and Maximum Magnitude values to the
appropriate limits. The Minimum Magnitude must be 1.0 or greater.
Depth
Setting the depth range is optional.
To retrieve all depths, set the Minimum and Maximum Depth
values to zero or leave these fields blank.
Depth is measured in kilometers.
Not all earthquakes have depths associated with them.
Intensity
Setting the intensity range is optional.
To retrieve all intensities, set the Minimum and
Maximum Intensity values to 0 or leave the fields blank.
Intensity values range from 1 to 12.
Most earthquakes do NOT have intensity values associated with them.
Rectangular Area Search
The Rectangular Area Search selects earthquakes that are located
within a defined rectangular grid.
Top and Bottom Latitude and Right and Left Longitude
must be set if the Rectangular Area was selected for
the Search Area.
The coordinates are in decimal degrees. North latitudes
and east longitudes are input as positive values.
South latitudes and west longitudes are input as
negative values.
Note: The search will not not span more than 180 degrees of
longitude.
Circular Area Search
The Circular Area Search selects earthquakes that are
located within a circular area defined by a center point
and a radius.
The coordinates are in decimal degrees. North latitudes
and east longitudes are input as positive values.
South latitudes and west longitudes are input as
negative values. The radius is in kilometers.
