• Introduction
  
• Background
  
• Code Assignment and Status
  
• Station Names and Geographic Regions
  
• Description of Listings
  
• Reporting Corrections and Additions
  
• Glossary of Abbreviations

Introduction

Approximately 100 years ago the first seismological observatories began making timed recordings of ground motion on a routine basis. Since that time, the number of stations has increased dramatically into the thousands, which has led to the necessity for indexing and cataloging these stations. This publication contains the latest listing of all seismograph stations in the world for which the United States Geological Survey, National Earthquake Information Center (NEIC), in its capacity as World Data Center A for Seismology, has assigned an international code, in cooperation with other international agencies, including the International Seismological Centre (ISC) in the United Kingdom, the International Data Center for the Comprehensive Nuclear Test Ban Treaty (CTBT/IDC) in Austria, the Incorporated Research Institutions for Seismology (IRIS) Data Center in Seattle, Washington, and the Federation of Digital Seismograph Networks (FDSN). This publication is an update of U.S. Geological Survey Open-File Report 85-719, Seismograph Station Codes and Coordinates, 1985 Edition. This website contains information for more than 10,000 codes.

Background

The earliest catalogs, such as a 1908 publication of the Bureau Central de l'Association Internationale de Seismologie (BCIS), listed all the stations operating in the world at the time; nearly 200 existed then, referred to by name and country. By 1931, in a second edition of the Bulletin of the (U.S.) National Research Council's List of Seismological Stations of the World, McComb and West listed 350 stations operating world-wide. By 1960, the U.S. Coast and Geodetic Survey (USC&GS) had adapted the station data for use on the computer and thus assigned three-letter codes to the stations from which they had received data. This informal code system became recognized as a valuable tool and began being used outside of the USC&GS. Consequently, the USC&GS published its list of station codes in 1962, followed by several revisions and addenda. The task of assigning codes was carried to the U.S. Geological Survey (USGS) when the National Earthquake Information Center was transferred there in 1972. About 1985 the NEIC was designated World Data Center A for Seismology.

Code Assignment and Status

Once the NEIC is informed that a new station has been established or is planned to be installed in the near future, a unique three- to five-character international code is assigned, and registered by both the NEIC and ISC. There are several code restrictions. Codes must begin with an upper case letter in the Roman alphabet, but the remaining characters may be any combination of upper-case alphanumeric symbols. Codes containing non-alphanumeric characters (such as AB-) have been accepted in the past, but are no longer assigned because they violate the FDSN Standard for Exchange of Earthquake Data (SEED) format and they cause problems for computer programs designed to parse telegraphic streams. In addition, codes which are the same as phase arrival designations (such as PKP); are identical to keywords used in the International Telegraphic Format for Seismic Data Exchange (such as VEL or STOP); or which would interfere with telegraphic exchange of the data (such as NNNN) are discouraged. Most of these codes which have not yet been assigned to a station are listed as forbidden. In addition, certain network codes (such as MNLO) have been listed as forbidden. These codes would only be assigned to a station operated by that network.

If a code is suggested by the station operator which meets the restrictions above, that code is assigned if it is available and if no other international code has already been assigned to that location. If no code is requested by the operator, NEIC will assign an available code which has some mnemonic relation to the station name and/or region or network. For example, GLD is assigned to Golden, Colorado; SPA is assigned to South Pole, Antarctica; and ETOR is assigned to Torete, Spain (E = España, the Spanish word for Spain). Frequently, networks which operate a large number of stations assign their own local codes to stations in their network. In general, if this local code is available, NEIC will also assign it as the international code for that station. If it is not available, a different international code will be assigned and the local code will be listed as a comment. With codes assigned recently, the international code is, whenever possible, derived by appending a fourth character representing the region or network to a three-character local code. It is strongly recommended that international codes be used when data are transmitted to international organizations such as NEIC, ISC or the European-Mediterranean Seismological Centre (CSEM/EMSC). Local codes are shown in lower case characters in the station code lists.

Because of the need for accurate station positions for hypocenter location programs, a new international code is assigned if a station is moved more than one (1) kilometer from the previous location. If the move is less than one (1) kilometer, a new code will be assigned if requested by the operator. Because of its importance for relocation studies of historic earthquakes, it is requested that operators notify international centers whenever a station is moved. It is also important to know the date that the move occurred. An attempt has been made in this publication to indicate that a station has been moved without having a new station code assigned by including a comment. However, there has been no exhaustive search of historic station locations to ensure that all stations which have moved have a comment stating that fact. If a new station position is obtained because of a more accurate survey, without the station being physically relocated, the coordinates will be changed in the station record, but a new code will not be assigned.

Once an international code is assigned, the code is listed as reserved until data are received by NEIC for that station. A reserved code will be deleted if the station is never installed. It may be deleted if the station is closed without ever sending data to an international center and the records are not retained or reasonably available for research purposes. Special caution should be exercised when using data listed for reserved codes. Frequently the coordinates listed are extremely preliminary, and in many cases no coordinates are available at all. The station may not, in fact, exist at the present time, but is simply planned for the future.

Once data are received by NEIC, or it is known that data have been sent to ISC, the station is listed as open. Once a station code is opened, its code will remain in the files permanently and will never (intentionally) be reassigned to another station. Unfortunately, in a few cases data inadvertently have been published by international centers using the same code for two different stations. Once this has been discovered, one of the codes has been appended with an asterisk (*) to correct the problem but retain the information for historical purposes. Occasionally, data from the same station have been assigned two (or more) international codes. In this case, the additional codes are listed as Alternate Abbreviations and cross-referenced to the primary international code.

When a station is known to have ceased operation, or a new code is assigned because all instruments were moved, the code status is changed to closed or unreported. It will be listed as closed if the station had previously been listed as open, and will be listed as unreported if the code had previously been listed as reserved. A code listed as closed remains a permanent entry and will not be reassigned to another station. A code listed as unreported will be reassigned only under the same circumstances described above for reserved codes. A code remains listed as open until NEIC or ISC have received definite information that the station has ceased operation. In general, a station is not considered closed simply because of relatively temporary instrument failures or similar interruptions which may prevent recording of data and/or transmission of data to international centers.

Station Names and Geographic Regions

Throughout this publication, geographic names or their spellings and country boundaries shown on the maps do not necessarily reflect recognition of the political status of an area by the United States Government.

Stations which are named for non-geographic entities such as the names of people or organizations are spelled as registered by the operator. Whenever possible, stations which are named for geographic places are spelled according to the official standard spellings recognized by the U.S. Board of Geographic Names, for both foreign and domestic names. The major exception to this is that at the present time it is not possible to incorporate diacritical marks into the station and geographic region names. Because of this, the standard name is spelled without diacritical marks (such as Quebec, instead of Québec), or a non-standard name is substituted (such as Graefenberg, instead of Gräfenberg). Diacritical marks are entered routinely into the NEIC station file, and it is intended that they will be used on this website in the future.

In addition to the primary station name, alternate names are listed in parentheses. Alternate names are listed for three reasons: when the geographic locality has undergone a name change; for old stations which were listed in historical station lists by a non-standard name prior to the assignment of international codes; and when the geographic locality has a generally-recognized conventional name. For the second case, the alternate name is retained even if it is unapproved, misleading or spelled incorrectly. One example of this is that the name Hatidyozima, though approved by no one, is still retained for station HJJ because it was spelled that way in pre-code station lists.

When a geographic entity has had its name changed, the primary station name listed represents the current name, not necessarily the name used at the time the station operated. Thus, for example, station code BHA in Zambia is listed with the primary name Kabwe, and the alternate name Broken Hill. This has been done so that the user can more readily find the place on a current map. Although an attempt has been made to keep all names as up-to-date as possible, an exhaustive check has not been made for all stations to be certain that the current or most correct standard name is listed.

The geographic regions which are used in all lists are assigned using the same scheme of regionalization developed by the ISC for their station listings, with a few additions and modifications. The basic scheme is that a particular geographic area is described by continent or ocean region, then by country, region and finally subregion. Countries are divided into regions and subregions only when the number of stations is determined to be sufficiently large that further breakdown is useful. In some cases, a large region with relatively few stations is subdivided simply because of the size of the area. As with station names, the geographic regions are spelled, as much as possible, in accordance with the official standard spellings of the U.S. Board of Geographic Names.

Description of Listings

The Alphabetical Listing By Station Code is a listing of codes, station names, locations and general information about each entry in the station file. The file is listed alphabetically by station code, according to ASCII sort order. This means that non-alphanumeric characters are listed first, numbers are listed next, and alphabetic characters are listed last. Thus code AD- appears before AD1, which in turn appears before ADA. However, code ABJ appears before both ABJ2 and ABJM, since a blank is significant in the sorting order and, in fact, is sorted ahead of all other printable characters. Local codes and alternate abbreviations are listed in sorted order with the primary international codes. Local codes are shown in lower case characters, and always follow the primary code which contains the same characters.

The next column contains the station name, its geographic region, and up to two lines of comments. The most common types of comments are dates of operation for the station, dates of operation for special instruments at the station, and information about local codes used for that station. To conserve space, all dates in the comments are given as single integers in year-month-day format. If the specific day, or month and day, are not known, no number is given for those fields. The dates given for special instrumentation is not necessarily the dates of operation for the entire station. For example, the comments for station code HLW (Helwan, Egypt) are:

opened 189909. WWSS opened 19620618.
records available since 1907.

This indicates that the Helwan station began recording in September, 1899, and that Worldwide Standard Seismograph Network instruments began recording at that site on June 18, 1962. The second line indicates the availability of records for research purposes. As a second example, the comments for station ALQ (one of several codes assigned to various sites at Albuquerque, New Mexico) are:

WWSS opened 19611117. HGLP 19720901-19780717.
DWSS 19810302-19820802. USNN opened 19920115.

This indicates that WWSSN equipment began operation at this site on November 17, 1961. Since no separate opening date is given, it may be inferred that either operation commenced with that instrumentation (as is the case here), or else this information is not known. High-Gain Long Period Network instrumentation operated at this site from September, 1972 to July, 1978, Digital Worldwide Standard Station Network instrumentation operated between March 2, 1981 and August 2, 1982 and U.S. National Network opened January 15, 1992. Since no closing date is listed for either the station or the WWSS equipment, again it may be inferred that the WWSS equipment and/or other equipment is still operating at the site or that this information is not known.

The geographic latitude, longitude and elevation above sea level are listed in the next three columns. Latitudes and longitudes are given in signed decimal degrees. North and east are positive numbers, south and west are negative. Elevations are given in meters and are the elevation of the sensor, not necessarily the elevation of the surface at the site. No attempt has been made to indicate proper precision for the decimal degree values which are listed, because unfortunately, reported precision is not stored directly in the current station file database.

The next column shows the network code for the organization which actually operates the station. Organizations which report data for other stations outside their own network are not listed here, but are shown in the comments. Network codes are either the station code of the primary station of the network (such as SLC for the University of Utah, Salt Lake City), or else a separate network code which is listed as a forbidden code (such as JMA for the Japan Meteorological Agency, Tokyo). These codes are forbidden simply to prevent their assignment to another station outside that network. The final column indicates the status of the code. A blank in this column indicates the station is open. Other possibilities are Reserved, Closed, Unreported and Forbidden. See code status for further details.

The Alphabetical Listing By Station Name is a listing of station names and codes listed alphabetically according to station name. Again, the sort is according to ASCII order. Alternate names are listed as separate entries from their primary names and are included in sorted order in the list. Stations which have the same name are alphabetized according to station code, not according to region. Thus Berlin, New York (code BERL) is listed ahead of Berlin, New Hampshire (code BNH). Alternate abbreviations, forbidden codes, local codes, and codes without names are not shown in this list.

The Geographic Region List is a list of stations grouped according to geographic region. These codes are sorted (ASCII sort order) first by continent or ocean, then country, region and subregion, and finally by station code. Thus station SLR (Silverton, South Africa) is listed under

AFRICA
SOUTH AFRICA
Transvaal

Three countries are in both Europe and Asia: Kazakhstan, Russia and Turkey. Since each of these has the largest portion of its territory in Asia, they are listed under Asia. Also, Egypt is in both Africa and Asia. It is listed under Africa. Forbidden codes, local codes and codes with unknown regions are not shown.

The Networks list shows seismological agencies and the stations they operate. Networks are listed alphabetically (ASCII order) by network code, followed by a brief description of the name and location of the network. Forbidden codes, alternate station codes, local codes and stations without network affiliations are not listed. In general, a network is not listed until that organization has operated at least four stations which have had international codes assigned.

Note that throughout this publication, the number zero is shown by the symbol 0 and the letter `` oh'' is shown by the symbol O.

Reporting Corrections and Additions

Reasonable care has been taken to ensure that the information given is as accurate and complete as possible. However, because this is an active database and station operations are constantly changing, there will be errors and omissions. Therefore, each station and network operator is encouraged to check the information for their stations and to report any corrections and additions to the NEIC. Information is especially needed about stations which have closed and about changes in coordinates, network affiliations and dates of operation.

Glossary of Abbreviations

Eng.		Engineering
G.S.C.		Geological Survey of Canada
Inc.		Incorporated
Inst.		Institute or Instituto
Int'l.		International
Nat.		National
O.B.S.		Ocean Bottom Seismometer
Org.		Organisation or Organization
Tech.		Technology
U.K.		United Kingdom
Univ.		University, Universite or Universidad
U.S.		United States
U.S.A.		United States of America

Inquiries should be directed to: Julie Martinez jmartinez@usgs.gov