Earthquake Parameters and Publication Criteria
Finger Quake
General Information
The list of recent earthquakes available through "finger quake@gldfs..." is
a service provided by the National Earthquake Information Service (NEIS) of the
U. S. Geological Survey. The NEIS is located at the National Earthquake
Information Center (NEIC) in Golden, Colorado, USA which also serves as World
Data Center A for Seismology. The NEIS is a member of the Council of the
National Seismic System (CNSS) which coordinates activities among the national
and regional seismograph networks, including "finger quake" services. The NEIS
is also closely associated with the U. S. National Seismograph Network (USNSN)
and cooperates with national and international seismological organizations
around the world. Unlike other members of the CNSS, the NEIS is responsible
for reporting on moderate to large earthquakes throughout the U. S. and large
earthquakes worldwide.
Earthquake Parameters
DATE-TIME is in Coordinated Universal Time (UTC). This is approximately the
same as Greenwich Mean Time (GMT) which is 5 hours later than Eastern Standard
Time (EST) and 8 hour later than Pacific Standard Time (PST). Geographic
latitude (LAT) and longitude (LON) are given in decimal degrees corresponding
to the usual map coordinates. Depth (DEP) is given in kilometers below sea
level. Six different magnitude types (MAG) may be quoted: Ml (local, the
original Richter magnitude), Lg (mblg), Md (duration), Mb (body wave), Ms
(surface wave), and Mw (moment). Since all magnitude types have been
calibrated with respect to one another, the differences are generally of
interest only to seismologists. Given the size, location, and available
information, the most meaningful magnitude will be quoted for each event.
Location qualities (Q) are A (good), B (fair), C (poor), and D (bad). The
quality refers to the precision with which the earthquake location has been
computed. A and B qualities mean that the location is quite reliable while
a C quality can be pretty uncertain. Bad locations will generally not be
reported. No quality implies a location held to the coordinates of another
organization (e.g., a regional network with better coverage of an event). The
comment is an automatically generated region name and can be misleading for
earthquakes near region boundaries.
Note that all 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. Differences between
parameters quoted here and in the media do not necessarily imply that the
"quake" list is in error. Small differences in locations and magnitudes
determined by different organizations are to be expected due to differences in
the information available. Also, in rare instances, substantial differences in
magnitudes can be due to real differences in interpretation, procedures, and
conventions.
Additional Information
Recent earthquake lists for specific regions of the U. S. are available from
other CNSS members using "finger quake" at: scec.gps.caltech.edu (Southern
California), andreas.wr.usgs.gov and quake.geo.berkeley.edu (Northern
California), geophys.washington.edu (Pacific Northwest), giseis.alaska.edu
(Alaska), seismo.unr.edu (Nevada), eqinfo.seis.utah.edu (Utah),
sisyphus.idbsu.edu (Idaho), info.seismo.usbr.gov (Wyoming & Western Colorado),
mbmgsun.mtech.edu (Montana), quake.eas.slu.edu (Central U. S.),
vtso.geol.vt.edu (Southeast), ldeo.columbia.edu (Northeast), and
tako.wr.usgs.gov (Hawaii). A recent Canadian earthquake list is available at:
quake@seismo.emr.ca (in English) and seisme@seismo.emr.ca (in French). Note
that some of the newer finger servers are temporarily redirected to our finger
list.
After earthquakes have scrolled off of the "quake" list, they will be
available in updated form from the Quick Epicenter Determinations (QED)
bulletin board. To access the QED, use "telnet neis.cr.usgs.gov", login as
qed (no password required), and follow the on-line directions. Note that
telnet is not like finger. In particular, you will need to interact with the
QED to obtain what you want. The QED includes earthquakes from about the last
six weeks and may be selectively searched. After six weeks, the earthquakes
are revised with more data and the Preliminary Determination of Epicenters
(PDE) bulletin is published (on paper). After about four months, the
earthquakes are revised again with even more data and republished as the PDE
Monthly Listing. For information on subscribing to the PDE or obtaining PDE
information electronically, call (303) 273-8500 during normal business hours
(Mountain Time Zone). Selective searches of our historical hypocenter database
are also available. For information on this service, send E-mail to Glen
Reagor at hdf@neis.cr.usgs.gov.
Much more extensive information derived from the USNSN is also available
automatically through our AutoDRM (Automatic Data Request Manager). Although
this service is intended to provide USNSN waveform data and instrument
responses for professional seismologists, it can also be used to obtain
information about earthquakes, activity at individual stations, the network
configuration, etc. To get started on the AutoDRM, send E-mail to:
autodrm@gldfs.cr.usgs.gov with the message text: PLEASE HELP all on one line.
Note that using the AutoDRM AMI command provides the same information as the
"quake" list, but for a longer time period.
Many other products and services are available from the U. G. Geological
Survey. For information on other earthquake related products such as maps and
CD-ROMs, try accessing the NEIC home page on the World Wide Web at
http://wwwneic.cr.usgs.gov.
Publication Criteria
The list available through "finger quake@gldfs..." has become the de facto
near-real-time bulletin of the NEIS. In order to make the "quake" list more
internally consistent and better integrated with other NEIC products,
particularly the Quick Epicenter Determinations (QED) bulletin board, it has
been desirable to define formal publication criteria for the "quake" list.
These criteria fall into two response time categories: immediate (e.g., within
two hours) and 24 hour response (normal working days only). Note that the
"quake" list may not be complete at the indicated thresholds if insufficient
information is available to either locate the event adequately or to determine
that it meets the publication criteria.
On an immediate basis, all Earthquake Early Alerting Service alarm events
will be made available to the "quake" list. At a minimum, this will includes
most earthquakes in the contiguous United States, Hawaii, and the more
populated areas of Alaska of magnitude 4.5 or greater, most other earthquakes
in the United States of magnitude 5.5 or greater, and most foreign earthquakes
of magnitude 6.5 or greater. In practice, many foreign earthquakes smaller
than a magnitude of 6.5 will also be provided on an immediate basis.
Typically, this would include earthquakes in Mexico of magnitude 4.8 or larger,
earthquakes in northern South America of magnitude 5.0 or larger, earthquakes
in central and southern South America and in the Kuril Islands of magnitude 5.5
or larger, and most other foreign earthquakes of magnitude 6.0 or larger.
Within 24 hours, most earthquakes in the contiguous United States of
magnitude 3.5 or larger, most earthquakes in Alaska of magnitude 4.0 or larger,
most earthquakes in Hawaii of magnitude 4.5 or larger, most earthquakes in the
Aleutian Islands of magnitude 5.0 or larger, and most foreign earthquakes of
magnitude 5.5 or larger will be provided to the "quake" list. Most earthquakes
in the United States which are felt will be provided to the "quake" list on a
24 hour basis even if they are smaller than a magnitude of 4.5. Events in
aftershock sequences which meet the 24 hour criteria, but not the immediate
criteria will be included on the "quake" list at the discretion of the seismic
analyst. Note that on weekends and holidays, meeting the 24 hour criteria will
be on a best effort basis.
Note
For your convenience, you can receive a copy of this information by E-mail
by sending any E-mail message to: qk_info@ghtmail.cr.usgs.gov.
