Earthquake Catalogs

Earthquake & Phase Catalog Formats

These are earthquakes located by the Southern California Seismic Network (SCSN) from 1932-present.

Output Formats

There are currently eight output formats available from this catalog search. Click on the underlined links below to see the specifics about data formats.

Event ID #

The event identification number is a unique number assigned to every event in the SCEDC catalog. This number is soley used by the SCEDC catalog. In other words, the same event may have a different id number in another catalog. To query for more than one event, separate each event id with a comma. Example: event1, event2, event3

Date Specifications

The date parameters are specified in the following format:

    year= year (1999-present)
    mm = month (1-12)
    dd = day-of-month(1-31)

Time is in UTC time

    hr = hour(1 - 24)
    min = min(1 - 60)
    sec = sec(1 - 60)

The date must be fully specified. If not an appropriate error message
will be displayed in your browser

Latitude and Longitude Parameters

Latitude and Longitude values are specified in decimal degrees, e.g. 34.50 for 34 and one-half degrees. Latitude values can range from -90 to 90, and longitude values can range from -180 to 180. Remember that longitude for California is WEST, and therefore should be specified as Negative (eg -121.5 for 121.5 degrees West).

On the 4-point polygon search, to enter the latitude and longitude parameters from the map, click on the map at each corner of the desired polygon. The current latitude and longitude position of the mouse is echoed on the screen. To move an existing pick to a new coordinate, press the mouse button while over the point to be changed and drag it the new position. Clicking on the map always moves the nearest pick to the selected location. You may also enter the latitude and longitude values manually by typing in the text regions to the right of the map. After entering the desired values, click on "Apply" to update the map.

Minimum - Maximum Paremeters

Search parameters that have min and max values are:

    Magnitude - specified in decimal, e.g. 5.7 or 2.6
    Depth - specied in decimal kilometers, e.g. 6.0 or 300.0

Event Type Description

Additional search parameters for selecting earthquakes include the following event type specifications.

  • eq - Earthquake: Seismic event within or close to the SCSN authoritative region. The event is futher qualified by geographic type or gtype. See geographic type description.
  • qb - Quarry blast: Event is an explosion associated with work at a quarry. In historical catalog, this may also include other types of explosions, such as seismic surveys.
  • nt - Nuclear explosion: Event is an explosion at a nuclear test site.
  • ex - Explosion: Event is an explosion from an unknown cause.
  • sh - Shot: Event is an explosion that is part of a seismic survey.
  • sn - Sonic Boom: Event is from a sonic shock wave.
  • st - Subnet Trigger: Event detected by network triggering algorithm. To be determined by analysts if energy is seismic.
  • th - Thunder: Event is associated with a thunder storm.
  • uk - Unknown: Event of an indeterminate type or very badly located event. Rarely used in current catalog.

Geographic Type Description

Additional search parameter for further qualifying earthquakes.

  • l - Local event: Earthquake within the SCSN authoritative region. In cases where a sequence or large event occurs near the border, local events could exist 10-25km (0.1 to 0.2 degrees) beyond the official boundary for catalog completeness.
  • r - Regional event: Seismic event occurred outside the network boundary in neighboring network. Location quality may not be refined by the SCSN.
  • t - Teleseismic event: Seismic event occurred at a distance greater than 1,000km from closest SCSN station.