ENS Glossary of Terms

Active

Use this to mark this region as active or inactive. This is useful for temporarily turning off email for vacations and such if you want to be able to reactivate it again without having to re-input the mail criteria. You will NOT receive any notifications that you missed after an Inactive account is set back to Active.

Address

Displayed are the email address(es) that are currently registered to your account. You may have up to 15 addresses associated with your account. To add a new address, use the 'Add New Email Address' button in the right column under the “My Email Addresses” section. This will prompt you for the address and what format messages you want to receive on it. It will then send you a confirmation message. Addresses are confirmed by sending you a random three-digit confirmation number to ensure that the address is working. Enter that number in the form provided. Addresses are not given or sold by the USGS to any outside organization. Note that for a new region, all addresses are selected by default. If there is an address you don't want associated with this region, then uncheck it. Privacy Policy

Affiliation

Please indicate your interest in earthquake notification.

Aftershock Exclusion

Large earthquakes generally will have many aftershocks. You may not wish to receive notification of all of them. This option will reduce the amount of mail you get after a large event. The ENS system will automatically define an aftershock zone and a magnitude threshold below which an earthquake will be considered an aftershock as follows: For events over M5.5 we will define an exclude region. The size of the aftershock zone is calculated according to the formula given by Wells and Coppersmith (1994).

The length is then multiplied by 2 and that number is used as the radius around the epicenter for the aftershock zone. We used a hexagon to approximate a circle. The magnitude limit is M-2 (2 units below the mainshock magnitude) within that region.

The length of time for the exclusion is based on the mainshock magnitude as follows…

M5.5-M6.0: 10 days
M6.0-M6.5: 20 days
M6.5-M7.0: 30 days
M7.0-M8.0: 60 days
M8.0+: 120 days

This option can be turned on or off at any time on the “Account Preferences” tab.

Day Magnitude

This is your magnitude cutoff for daytime hours. You will be notified of any events greater than this magnitude during your specified daytime hours. See also Night Magnitude.

Day Begins/Day Ends

You need to specify hours to be considered 'daytime'. Times are based on a 24-hour clock. The 'end' value must be equal to or greater than the 'begin' value, and both must be in the range of 0-23 hours. If the day and night hours are equal, then all hours will be considered 'daytime' and you will get all notifications for events greater than your specified daytime magnitude. Note that the hours are specified in local standard time in your time zone that you specified when you opened your ENS account. If you need to change your time zone, use the 'Edit your account' function on the main page.

For an email account, start and end times of 00:00 are appropriate. Day and night hours are only really relevant for pagers or cellphones, where you might want to designate a night-time where you would receive fewer notifications.

Defer notifications during night hours

If a notification or an update occurs during your night hours that does not meet the magnitude threshold for nighttime, you will get the message at the start of the next day if you select “Yes”, and you will not get the notification or update if you select “No".

Event Depth

This option can be seen only if you indicate an affiliation of Scientist/Network Operator. Use this if you want to be notified about events in a certain area only within a certain depth range.

Language

Select your language. English and Spanish are currently the only choices.

Message Format

The message format is related to the type of account. The 'HTML' and 'long' formats are suitable for email, while the 'short' format is more appropriate for cell phones, pagers, and PDAs. The 'raw' format is a machine-readable compact format.

Example of Short Format:

  M6.2 21:44 5/29 -30.2 -178.1 105km SSW of Raoul Island, Kermadec Islands US yra7 31b86

The information included is:

magnitude time (UTC) date latitude longitude descriptive location event_id email_id

Example of Long Format:

  == PRELIMINARY EARTHQUAKE REPORT ==
  **This event supersedes event US hsal.

  Region:                     SOUTHERN QUEBEC, CANADA
  Geographic coordinates:     45.026N, 73.881W
  Magnitude:                  3.7 Ml
  Depth:                      12 km
  Universal Time (UTC):       9 Jan 2006 15:35:40
  Time near the Epicenter:    9 Jan 2006 10:35:40
  Local time in your area:    9 Jan 2006 08:35:40

  Location with respect to nearby cities:
    19 km (12 miles) NE (54 degrees) of Chateaugay, NY
    23 km (15 miles) NW (310 degrees) of Altona, NY
    24 km (15 miles) WNW (287 degrees) of Mooers, NY
    60 km (37 miles) SSW (192 degrees) of Laval, Québec, Canada
    60 km (37 miles) SSW (204 degrees) of Montréal, Québec, Canada

  ADDITIONAL EARTHQUAKE PARAMETERS
  __________________________________________________
  event ID                     : LD 2006010900
  version                      : 1
  number of phases             : 24
  rms misfit                   : 0.24 seconds
  horizontal location error    : 0.4 km
  vertical location error      : 1.1 km
  maximum azimuthal gap        : 75 degrees
  distance to nearest station  : 31.3 km

  Flinn-Engdahl Region Number = 447
  This is a computer-generated message and has not yet been reviewed by a seismologist.
  For subsequent updates, maps, and technical information, see:
  https://earthquake.usgs.gov/earthquakes/eventpage/ld2006010900#executive
  or
  https://earthquake.usgs.gov/

  CISN Southern California Management Center
  Caltech Seismological Laboratory
  U.S. Geological Survey
  http://www.cisn.org/scmc.html
  ________________________________

  DISCLAIMER: http://earthquake.usgs.gov/ens/disclaimer.html

  This email was sent to lisa@usgs.gov

  You requested mail for events within the 'East Coast' region
  for M2.5 between 08:00 and 23:00 and M4.0 other times.

  To change your parameters or unsubscribe, go to:

  http://earthquake.usgs.gov/ens  ---

Example of HTML Format:

HTML format

Most of the information is self-explanatory, but the information included in the PARAMETERS section is:

Nph - number of phases
Dmin - distance to nearest station (km)
Rmss - rms misfit (seconds)
Gp - azimuthal gap (degrees)
M-type - magnitude type

Networks

You will only see these if you have indicated an affiliation of Scientist/Network Operator. These are the seismic networks to accept events from. You will only be notified of events declared by these networks. By default, all networks are selected (except AT, which provides preliminary solutions that are always superseded by NEIC or regional network locations within a few minutes). If you know that you want to exclude one or more, then uncheck them. Otherwise, leave them all checked. The choices are:

CI: Southern California
NC: Northern California
NN: Nevada
UU: Utah
UW: Pacific Northwest
AK: Alaska
NM: New Madrid - University of Memphis
HV: Hawaii Volcano Observatory
PR: Puerto Rico Seismic Network
US: NEIC worldwide network
SE: Southeastern U.S.
WY: Yellowstone Seismic Network - Wyoming
AR: Arizona Seismic Network
AT: Alaska Tsunami Warning Center
TX: Texas Seismological Network

Night Magnitude

This is your magnitude cutoff for non-daytime hours. You will be notified of any events greater than this magnitude during these hours. Typically your night magnitude will be larger than your day magnitude so that you're less likely to get notifications while you're sleeping, but there is no reason why night can't be the same as the daytime setting. It all depends you your personal schedule and when you want to receive alerts. This is only really applicable if you are having alerts sent to a pager or cell phone that can wake you up in the middle of the night. If you are having alerts sent to an email account that won't wake you up in the middle of the night, then you will probably want the night magnitude to be the same as the day magnitude. You will NOT receive any notifications that you missed after the Night Magnitude time period is over and the Day Magnitude period begins. See also Day Magnitude.

Region Name

This is an optional field where you can enter a name for your region. The name is used to identify the region on your account display, and also in the footer of any messages sent to you.

Time Zone

Select your time zone, based on your offset from GMT. For areas where daylight saving time is implemented, select your time zone based on the offset for Standard Time. What's my time zone?

Updates and deletions for events

Updates are sent for previous notifications if the magnitude changes by more than 0.4 or the location changes by more than 0.5 degrees of latitude or longitude. Deletion messages are sent if the system previously sent a notification for a nonexistent event. If you do not want to receive any updates or deletions, select “No”.