NSL Earthquake Catalog Search Help

There are currently four earthquake catalogs available.

• The Current UNR Catalog lists all events located by the Seismological Laboratory at the University of Nevada, Reno, from the beginning of the year 2000 to the present. This catalog is rebuilt daily from our time-pick, association, and relocation database. It is thus an active product, and any entry may be updated and new entries added with every rebuild. The catalog contains both automatic, unreviewed locations as well as analyst-reviewed locations. Reviewed locations always trump automatic notices.

  Our earthquake locations are made in cooperation with the California Integrated Seismic Network and the Utah Seismographic Stations, with whom we trade real-time seismograms. The UNR catalog will include the most events within our areas of coverage. It will also include some events within the areas of the adjoining networks. Magnitudes are local Richter magnitudes computed from wave amplitudes seen on high-quality seismometers throughout the region.

• The UNR Historical Catalog lists all events catalogued by the Seismological Laboratory at the University of Nevada, Reno, from the first known Nevada earthquake in 1852 through 1999. This catalog contains only analyst-checked events, with events interpreted as artificial blasts not included. Local magnitudes were estimated from coda durations until 1999, calibrated against synthetic Wood-Anderson records since 1994. Some local events too large to yield duration magnitudes have been assigned local Richter magnitudes. Local magnitudes derived from high-quality digital records began to be used in 1999; after 1999 all magnitudes are M_L local magnitudes. The catalog is believed to be complete above magnitude 2.0 for eastern California and western Nevada since 1989. The historical catalog thus represents an accurate record of earthquake occurrence.

  This catalog was assembled for 1852-1979 to include felt events throughout western Nevada and eastern California, and since 1979 continues to include events having magnitudes above 2.0 in that area. More details on large historical events, and references to data sources, can be found in the paper Earthquake Occurrence in the Reno-Carson City Urban Corridor by C. dePolo et al.

• Nevada Broadcast of Earthquakes contains automatic, unreviewed, and often erroneous event notifications generated by computer every 5 minutes. Most of the notifications have not been checked by any analyst. Please call the Seismological Lab at 775-784-4975 to verify any NBE event. Some notifications are posted with the word ``Upd'' at the end; those are the only ones that have been reviewed and updated by an analyst. The NBE contains the 100 most recent events, or a larger number to guarantee coverage of the past 14 days. This service is meant to promote rapid earthquake response. However, the NBE is not intended to produce an accurate record of earthquake occurrence, magnitudes, or locations.

• Latest Reviewed Earthquakes contains up to 200 of the most recent NBE events that have been reviewed and verified by an analyst. This is a recent record of accurate earthquake locations and magnitudes that will be included in the next published catalog. It is incomplete, however, and does not give an accurate record of earthquake frequency or occurrence.

• Some obsolete and experimental catalogs are available from a local search page:
  • California-Nevada Combined Catalog for magnitudes 3.0 and over, listing events catalogued in southern California by the California Institute of Technology and in the western and southern Great Basin by the University of Nevada, Reno, from 1860 to April 1993.
  • California-Nevada Combined Catalog for all magnitudes, listing all events catalogued in southern California by the California Institute of Technology and in the western and southern Great Basin by the University of Nevada, Reno, from 1860 to April 1993. Searching this catalog will be slow, as it contains over 300,000 events.

There is currently one output format available from the catalog search, locally called the CAT format. Searches return a column- and whitespace-delimited list of events, one per line. In Fortran terms they are arranged:

yr mo da hrmin sec  lat   lon   dep   mag  qual
I4 I3 I3 I5    F8.4 F10.4 F10.4 F10.4 F7.2 A5

There are some events in the UNR Historical Catalog for 1990-1999 having more than 60 in the seconds column (the times are otherwise correct) that violate the column limits but are still whitespace delimited.

Prior to the year 2000 event magnitudes in the UNR Historical Catalog were usually estimated from coda durations on high-gain vertical-component seismometers. Since 1992, these duration magnitudes had been calibrated against local Richter magnitudes from synthetic Wood-Anderson records. Some larger-magnitude local events cannot yield coda-duration estimates; these may have local Richter magnitudes instead. Starting in 2000 we compute magnitudes with synthetic Wood-Anderson records created from our high-dynamic-range seismometer records.

UNR quality ratings have two letters; the first indicates the epicentral location accuracy while the second indicates the hypocentral depth accuracy. Quality ``a'' is best. Events from the Nevada Broadcast of Earthquakes have only the most general quality notation: "Pre" for a preliminary automatic location unchecked by an analyst; and "Upd" for a location redone by an analyst.

(Event magnitudes and quality ratings in the legacy California/Nevada Combined Catalogs are detailed in a separate document.)

Date and Time parameters

Date,time parameters can be specified in the format:

• yyyy/mm/dd,HH:MM:SS

• yyyy = year (including century)
• mm = month (1-12)
• dd = day-of-month(1-31)
• HH = hour (0-23)
• MM = minute (0-59)
• SS = second (0-59.9999)

Latitude and Longitude values can be specified in the format:

• decimal degrees, such as 39.50 for 39 and one-half degrees.

Page maintained by J. Louie
Last updated: 15 Aug. 2001