How this query works

We have loaded events from several catalogs including the "finger quake" list, QED, WHDF and MHDF dating from the early 1960s to the present. (definitions of catalogs). We also provide mapping and WEED file output options.

• You must enter a value in at least one field.
• You may select ALL, PREFERRED or any combination of catalogs. (see definition of catalogs)
• Contributor refers to the entity that contributes the hypocenter information and/or the magnitude to a catalog listing.
• You can search by latitude and longitude OR Flinn-Engdahl codes or text - but not both.
• Start and end times :
  • Time entries must contain a year, month and day. You may not enter a partial time like month and year.
  • If you do not enter any time parameters, the query will be for all time.
  • If you enter a start and end time, the query will be for that time period.
  • If you enter a start time but no end time, the query will be from that time to the present.
  • If you enter an end time but no start time, the query will be all entries before the specified end time.
• For those fields using >= and <= :
  • values in both boxes will result in a query between the first value and the second value
  • only value in the >= box will query for all values greater than or equal to that value
  • only value in the <= box will query for all values less than or equal to that value
• You can review the list of Flinn-Engdahl regions by which to search.
  • If you select a REGION CODE you MAY NOT enter a SEISMIC CODE or REGION text (it's redundant).
  • If you select a SEISMIC CODE you MAY also search by REGION text.
    Example: You may want to search for events in the Oregon area but only for those that happened off the coast. You would enter the appropriate SEISMIC CODE and the word 'coast' in the text box.
• The REGION text is already wildcarded for you - you don't need to wildcard for single word strings.
• You can search for multiple word stings in REGION (like 'SEA OF') but you MAY NOT search for comma separated strings (like OREGON, USA).

Grouping Events

The IRIS DMC populates the event portion of the database from different earthquake catalogs including several from NEIC as well as the ISC. Due to this fact, there are sometimes multiple hypocenter estimates for a single event. Additionally, many of the catalogs provide more than one estimate of magnitude. For this reason there are frequently several records (rows) returned from a query of our event database. The event grouping feature allows you to select space-time criteria that result in multiple rows being grouped together because they are from the same event. The top of the page provides information as to the number of groups (events) and the total number of hypocenter/magnitude estimates (records).

 

Mapping Events

When "MakeEvent Map" is selected on the results page, one event per group is selected for the map. The event listing selected is the one with the largest magnitude for that group. If there are two listings with the same magnitude in a group, then the one from the most accurate catalog for that time period is selected. ( more details )

Catalog definitions

NEICALRT

List distributed by NEIS (National Earthquake Information Service) of the USGS via email and used to trigger the IRIS SPYDER® system. These events are NOT included in the "PREFERRED" catalog algorithm because they are redundant (of FINGER) and do not include all events reported by FINGER.

 

FINGER

List distributed by NEIS (National Earthquake Information Service) of the USGS through the "finger quake@gldfs.cr.usgs.gov" service. The earthquakes on the "quake" list have been reviewed by a seismic analyst. However, in the interest of timeliness, locations and magnitudes are entered once and not updated on the list. This list contains data for the past 7 days. Once an event rolls off the list it appears on the QED (see next definition).

QED

Quick Epicenter Determinations - distributed by the USGS NEIS 7 days behind real time. These data are extremely preliminary and the parameters of the earthquakes are subject to change as more data are used to relocate the earthquakes. The QED rolls over to the WHDF (see next definition).

 

WHDF

Weekly Hypocenter Data File - distributed by the USGS NEIS. Covering the time period following the Monthly data up to four weeks behind the current week. The Weekly PDE (Preliminary Determinations of Epicenters) data are replaced by the Monthly PDE data as soon as they become available.

 

MHDF

Monthly Hypocenter Data File - distributed by the USGS NEIS. This list is the most complete computation of hypocenters and magnitudes done by the USGS NEIC. It is normally produced a few months after the events occur. The publication is called "preliminary" because the "final" computation of hypocenters for the world is considered to be the Bulletin of the International Seismological Centre (ISC), which is produced about two years after the earthquakes occur.

 

ISCCD (limited availability)

Bulletin of the International Seismological Centre (ISC). List of earthquakes two years behind real time.

 

PREFERRED (SeismiQuery option only)

When this selection is made, the resulting list of events will include events selected from the catalog that is considered to be most accurate for that time period. The order in which the catalogs are listed above is the reverse order in which events will be selected as "preferred." (That is, the ISCCD being most preferred and so on.)