Earthquake Catalog Search Help
Input Data Set
Date,Time parameters
All time in the earthquake catalog is referenced to UTC.
Date and time parameters can be specified in one of several formats:
- yyyy/mm/dd,HH:MM:SS
- yyyy.doy,HH:MM:SS.
where:
- yyyy = year (1900-present)
- doy = day-of-year (1-366)
>li>mm = month (1-12)
- dd = day-of-month(1-31)
- HH = hour (0-23)
- MM = minute (0-59)
- SS = second (0-59.9999)
If the date is not specified, a search over the full catalog is performed.
Latitude and Longitude parameters
Latitude and Longitude values can be specified in the following format:
- decimal degrees, such as 39.50 for 39 and one-half degrees.
Latitude values can range from -90 to 90, and longitude values can range
from -180 to 180. Please remember that:
- Longitude for California is WEST, and therefore should be specified as
NEGATIVE (eg -121.5 for 121.5 degrees West).
- Since longitude is signed, a search between longitudes of -117 and -121
should be specified with a Min longitude = -121 and a Max
longitude = -117.
-
No search area (neither a simple lat/lon box nor a polygonal region may
cross the -180/180 degree longitude. If you wish to search a region that
crosses this boundary, you must perform 2 distinct searches. For example,
if you wish to search the 15 degree region between 175 degrees longitude and
-170 degrees longitude, you must perform the search as 2 distinct request
using:
- First search boundary:
- Minimum Longitude: 170
- Maximum Longitude: 180
- Second search boundary:
- Minimum Longitude: -180
- Maximum Longitude: -170
Additional search parameters
Additional search parameters for selecting earthquakes may be specified by
entering the appropriate keyword=value strings in the "Additional
Search Parameters" box.
Most search parameters are
min/max parameters
which allow you to provide minimum and/or maximum values for specific fields in
the event catalogs.
However, you may also select earthquakes within a specified
annulus (or ring) around a location with the
delta parameter, or specify a
polygonal region to
confine your earthquake search to a more complex region than a simple
latitude/longitude box.
Min/Max parameters
Search parameters that have min and max values can be specified by the strings
- minkeyword=value
- maxkeyword=value
where the strings min and max preceed the keyword. If you
only specify one end of the range (either the min or the max value), the
other end of the range will be determined appropriately.
For example, to specify the that you want events where the closest station
is between 1 and 20 km, you would specify
and to specify you want events where the closest station is <= 25 km from
the epicenter, you would specify
There should be NO blanks in the parameter=value string.
Multiple parameters may be entered on the same line if they are separated by
one or more blanks.
The following keywords can be used in min and max values parameter
strings:
- sta - number of observations used for solution (range: 0 to ...).
- close - distance of closest station to epicenter (range: 0 to ...).
- rms - root-mean-squared residual of solution (range: 0. to 1.).
- gap - azimuthal gap (range: 0 to 360).
- errtime - error in time (range: 0 to ...).
- errhor - horizontal error (range: 0 to ...).
- errdepth - vertical error (range: 0 to ...).
- quality - quality of event (range: 0 to 1).
- magobs - number of observations used to compute magnitude (range: 0 to ...).
Delta parameter
You may search for all earthquakes that are within an annulus
(ie between a minimum and maximum distance) from a location with
the delta parameter.
- delta=lat,lon,mindist,maxdist
where lat,lon specify the latitude and
longitude of the center of the
circle, and mindist,maxdist specify the minimum distance and maximum
distance in kilometers (km) of earthquakes from the specified location.
Only earthquakes that are between mindist and maxdist kilometers from
the specified location will be selected.
There should be NO blanks in the delta=value string.
Examples:
- delta=38.5,-118.5,0,50
specifies a circle (annulus with inner diameter of 0) of 50 km around
the location (38,5,-118.5). The program will select only earthquakes
that are located within this circle.
- delta=38.5,-118.5,20,50
specifies an annulus (ring) of 20 to 50 km around
the location (38,5,-118.5). The program will select only earthquakes
that are located within this annulus.
Polygon parameter
You may specify a polygonal search area with the polygon parameter.
- polygon=lat_1,lon_1,lat_2,lon_2,....,lat_N,lon_N
where lat_i,lon_i specify the latitude and
longitude of the i-th vertex of the polygon.
There should be NO blanks in the
polygon=value string.
Example:
- polygon=37.4,-122.7,37.9,-122.75,37.9,-122.3,37.0,-122.0
defines a polygon that encloses that Bay Area Peninsula.
The polygon must NOT cross the -180/180 degree longitude boundary,
since the definition of the polygonal region becomes ambiguous.
Event type parameter
You may specify types of event with the etype parameter.
- etype=type1,type2,....,typeN
where typeI specify a type of event.
There should be NO blanks in the
etype=value string.
Example:
- etype=uk,ts,le
defines a search on unknown events, teleseims and local events.
Event source parameter
You may specify sources of event with the source parameter.
- source=source1,source2,....,sourceN
where sourceI specify an event source .
There should be NO blanks in the
source=value string.
Example:
- source=NC,BK
defines a search on events from the NCSN and Berkeley.
Magnitude type parameter
You may specify types of magnitude with the mtype parameter.
- mtype=mtype1,mtype2,....,mtypeN
where mtypeI specify a magnitude type .
There should be NO blanks in the
mtype=value string.
Example:
- mtype=d,l,w
defines a search on magnitude types Md, Ml and Mw.