FDSN Event Web Service

Description Usage URL Builder Help

The fdsnws-event web service returns event (earthquake) information from the catalogs submitted to the NCEDC.

Events may be selected based on location, time, catalog, contributor and internal identifiers. By default, events are retrieved
from the NCSS catalog. These default results include only that catalog's primary origin and primary magnitude for each event,
they may optionally include all available origin and magnitude estimates.

Results are returned as XML in QuakeML format (schema here) or in text format.

This service is an implementation of the FDSN web service specification version 1.

Nomenclature primer: An earthquake is referred to as an event. Events are published by different entities in compilations known as
catalogs. The same event may appear in multiple catalogs. There are often multiple estimates of an earthquake's time and location;
each is known as an origin or an origin estimate. Each of these origins may have one or more estimates of an earthquake's size,
known as magnitude or magnitude estimate.

Web service clients that use this service can be found at http://service.iris.edu/clients/. In particular the command-line FetchEvent
script will request information from this service, parse the returned XML and print or save simple ASCII information.

Event catalogs The NCEDC receives earthquake location and magnitude information from the following sources: (catalogs,contributors) * NCSS: Northern California Seismic System. * EGS: Enhanced Geophysical System. * DD: Double Difference Catalog. By default, the NCSS catalog is queried, though any catalog may be specified via the catalog parameter. For a complete list of the NCEDC held event catalogs, click the catalogs link at the start of this section. The same event may be published in multiple catalogs.
Event selection The service allows events to be selected by the following criteria: * Geographic region, rectagular area or radius from a point * Time range * Depth and magnitude * Catalog and contributor * Events updated after a specific date
Output format
QuakeML The QuakeML format is an XML schema originally created at ETH Zurich and collaboratively developed with international partners. For further information see https://quake.ethz.ch/quakeml/. As specified in the FDSN web service specification this service returns in the QuakeML 1.2 schema.
Text The text format contains key event parameters separated by vertical bar characters (|). An example: The text format does not include phase arrivals or mechanism information.
Preferred origins By default, only the selected catalog's preferred origin will be returned. These origins have been designated as preferred by the catalog's contributor. To retrieve all origins associated with an event, specify includeallorigins=true. Only origins relating to the selected catalog will be returned.
Preferred (Primary) magnitudes For cases where only a single magnitude per event is desired, the NCEDC designates one magnitude (from the selected catalog) as primary for each event.
Contributor Search Using the contributor parameter will confine results to events that contain origins provided by that contributor. Additionally, the results will be modified as described in this table:
Additional Parameters Information returned
none Preferred origin, preferred magnitude
includeallorigins All origins, preferred magnitude
includeallmagnitudes All magnitudes
includearrivals Include supporting information such as arrivals, amplitude and codas
includemechanisms Include supporting information such as moment tensors and focal mechanisms

Geographic search

Using latitude / longitude boundaries (Bounding Rectangle)

The following four parameters work together to specify a boundary rectangle. minlatitude, maxlatitude, minlongitude,
maxlongitude.  All four parameters are optional, but may not be mixed with the parameters used for searching within
a defined radius. Values are specified in decimal degrees.

Using a radial boundary (Bounding Radius)

The following four parameters work together to specify a boundary as a great circle radius around a coordinate. latitude, longitude,
maxradius, minradius.All values are specified using decimal degrees.