ENS Documentation

Table of Contents


Introduction

The U.S. Geological Survey Earthquake Hazards Program Earthquake Notification Service (ENS) is a customizable system provided free to everyone. New accounts receive, by default, all earthquakes with magnitude 6.0 or greater; you can subsequently customize these settings to better fit your needs. You can receive earthquake notifications for any earthquakes located by the ANSS/NEIC (Advanced National Seismic System/National Earthquake Information Center) in the U.S. and around the World. Information for earthquakes in the U.S. is generally available within 5 minutes; information for earthquakes elsewhere in the World is generally available within 30 minutes. Within the U.S. we locate earthquakes down to about M2.0, and about M4.0 for the rest of the world. Please read the DISCLAIMER at the bottom of this document.

Customizable Options:


Subscribe

Subscribe Step 1 - Send Sample Email

ENS offers a quick way to preview an event message by allowing you to send yourself a sample email. The sample email is in the standard ENS HTML format.

Included in the sample email is a link that allows you to quickly sign up for ENS. Clicking this link confirms that you own this email address, which allows you to skip step 3 of the subscription process.

To send a sample email, click the Try ENS or Subscribe button on the ENS homepage. This will bring up a dialog box like the following:

Picture of send sample email page

Enter your email ENS will send the sample email to this address. If you choose to sign up via the sample email, this email address will become the primary address associated with your account.

Enter the word shown in the image above Copy the 5 letters from the image into the text box below. The letters are not case sensitive.

The image is called a CAPTCHA, which contain pseudo-randomly generated letters. The CAPTCHA prevents automated programs from filling out the form and sending unsolicited ENS emails.

If you cannot read the letters in the image, click Get New Code to generate 5 new letters. If you require assistance, please email the ENS Administrator: ensadmin@ens.usgs.gov



Subscribe Step 2 - Set up Account

Register page

A Spanish version of the form is available via a link at the top of the page.

Email This email address will be the primary address associated with your account. If you reached the Set up Account page via a sample ENS email, the email field will be filled in for you. If you clicked directly on the Sign Up for ENS link, you must enter an email. After clicking Subscribe, you will need to check your email to receive your confirmation code. You will have an opportunity to enter additional email addresses using the My Email Addresses tab once you register.

Username This can be any username you want to use. If it is already taken, a red X will appear next to the field, along with a message notifying you of the error. If you ignore the error, you will see a message when you submit the form, and will be given the opportunity to choose another username.

If you are signing up via a sample email, ENS will attempt to create a username for you based on the first part of your email address.

Password/Confirm Enter a password twice, once in each box. This will allow you to login and manage your account.

Subscribe Please read the Disclaimer in the box below the Subscribe button. Clicking Subscribe will create your account then either log you in to ENS, or display a message instructing you to check your email for a confirmation code.

In order to send event notifications at the proper hours, the system will attempt to guess your time zone. After registering, you can check if it is correct by going to the Account Preferences tab. What's my time zone?

ENS will remember the language (English or Spanish) you used when filling out the form, and present content in this language whenever possible. Your language preference, along with many other account settings, can be changed in the Account Preferences tab.

 

Subscribe Step 3 - Confirm Email (Only for users that did not request a sample email)

Confirmation email message

After subscribing, you need to confirm that you own the email address you used to sign up. ENS will send you an email with a 3 digit confirmation code, which you have to enter after logging in.

Confirming your email:

 

At this point your ENS account is set up and ready to receive event notifications.


Navigating the ENS Webpages

ENS tabbed navigation

The yellow tabs at the top of the ENS user page allow you to manage your profiles, see recent events sent to you, manage your email addresses, edit your account information, use a text-based version of ENS, and obtain ENS documentation. The Logout link can be found in the upper-right corner of every page.

Note that Javascript is required to use the map functionality of ENS. If you don't know what this means, you can most likely ignore this fact because over 95% of browsers already have Javascript enabled.

It is highly recommended that you use a modern browser such as Internet Explorer 7+, Firefox 2+, or Safari 3.1+.


Managing Your ENS Profiles

The ENS homepage uses a Leaflet Maps based interface to display all your profiles in one convenient place. The map allows you to manipulate existing profiles, add new profiles, change profile settings, and delete profiles.

Default map

The first time you log in, you will see a map with two default Predefined profiles for the World and the United States. The United States profile appears as a group of 3 blue polygons, while the default World appears as the green shaded rectangle. You may edit or delete one or both of these.

In Leaflet maps, you can change the view by clicking and dragging to pan, and by using the control on the left. The map automatically wraps horizontally, so, depending on your zoom level, you may see more than the entire world.

Profile list

The My ENS Profiles box on the right side of the map shows a list of all of your profiles. The colors on the list correspond to the colors of the profile on the map. Click the name of a profile to edit that profile. Read more about editing profiles.

 

Profile Information Panel

Below the map is a blue bar, which expands when a profile is clicked or added. This is the Profile Information Panel.

Profile information panel

The Profile Information Panel allows you to set the following options:

Profile Name You may give this profile a name. This is to help you keep track of your profiles.

Send emails to: All email addresses associated with your account will be listed here. Place a check mark next to all addresses you would like to use to receive event notifications for this profile.

Magnitude These values are the minimum magnitudes for which you want to receive notifications. Read about Daytime Magnitude and Night Magnitude.

Active Should this profile send event notifications? Check 'Yes' to allow notifications. Check 'No' to suspend/disable notifications.

 

Add New Profile

Add New Region control

To add a new ENS profile, you must use the control in the top right corner of the screen. The two types of profiles are (from left to right) Predefined, and Custom.

Adding a Predefined profile

Clicking on the predefined profile button Predefined region button will hide all your existing profiles and show a blank map of the world. The Add New Region control will expand and display a list of the available predefined regions.

Add new region control expanded

Picking a region from the drop down menu will add the region to the map.

When the predefined region is added to the map, the Profile Information Panel below the map was expanded.

Add new region control expanded

Note that the default magnitude threshold for new profiles is M6.0. Earthquakes this large happen somewhere in the world about once every three days on average, although it's not uncommon to go for a week or more without having one. If you are setting up a notification profile for any place other than the most active parts of the world, you will probably want to set the threshold lower than M6.0. Appropriate values are generally something like M4.0-M4.5, or M1.5-M2.0 for less-active areas like Europe or the eastern U.S.

The new profile will not be saved until you click Save in the Profile Information Panel.

Add new region control expanded

Adding a Custom profile

Click the Custom profile button Polygon region button to start drawing a custom region. The toolbar on the left below the zoom buttons controls drawing. The three buttons are for drawing polygons, rectangles, and circles. To begin drawing, click on the one of the three draw buttons. Note that all other profiles are hidden until you finish drawing.

Drawing a custom region

Drawing a polygon

Click the 'draw a polygon' button on the toolbar:

Drawing a polygon

Click the map to draw the polygon. Click the last point to close the polygon.

Drawing a polygon

The new profile will not be saved until you click Save in the Profile Information Panel.

Adding a Rectangular profile

Click the 'draw a rectangle' button:

Drawing a polygon

Click the map to start drawing a rectangle. Note that all other profiles are hidden until you finish drawing. A rectangular profile is defined by clicking one corner and then dragging the pointer to the opposite corner.

Drawing a rectangular region

The new profile will not be saved until you click Save in the Profile Information Panel.

Adding a Circular profile

Click the circular profile button:

Circular region button

Click the map to start drawing a circle. Note that all other profiles are hidden until you finish drawing. First, click the point you want to be the center of the circle. Then drag the pointer to define the radius.

Circles will become distorted near the poles. This is because Leaflet maps uses a mercator projection. In general, circles work best for defining relatively small areas. A circle with a radius over a 250 miles or 400km will be distorted by the curvature of the Earth.

Drawing a circular region

The new profile will not be saved until you click Save in the Profile Information Panel.

Editing A Profile

Parameters for any ENS profile, including the two default profiles, can be modified. On custom profiles that you created, you can also change the profile's coverage area. You cannot change the coverage area of pre-defined profiles.

Click the profile on the map or the profile name in the My ENS Profiles list to edit the profile.

You will notice that the Profile Information Panel expands below the map. Here you can set any of the parameters discussed above.

All other profiles will be hidden when editing a profile.

Custom profiles have a control button on the map, indicating that the custom region is editable.

Editing a polygon region

To edit a custom polygon, click on the edit control button. Then, each corner of the polygon will have a small white box, and each line segment of the polygon also has a transparent white box at its middle. Dragging these transparent boxes allows you to add new points to the polygon. To remove a point, double-click on the box at the vertex you want to remove.

Editing a polygon region

You can click the Cancel button before saving to undo all changes to the current profile. When you are done editing your polygon, click the OK button to finish editing. Changes will be saved when you click the Save Changes button at the bottom of the profile form.

Click Save Changes when you are finished editing.

Rectangular profiles show four boxes at the corners, and one at the center when the rectangle is editable.

Editing a rectangular region

Drag the corner icons to reshape the rectangle. Click and drag the center icon to move the rectangle without changing its shape. Clicking Cancel or Discard Changes will undo all modifications to the current profile.

Click Save Changes when you are finished editing.

Circular profiles show an icon at the center and an icon on the radius when the circle is editable.

Editing a circular region

Drag the center icon to relocate the circle without changing its size.

Drag the icon on the circle's radius to resize the circle.

Click Save Changes when you are finished editing.

 

Notes:


Managing Your Email Addresses

ENS allows you to associate up to 15 email addresses with your account. Click on the My Email Addresses tab to show a list of the addresses you currently have registered with ENS.

Email address list

Each email address has several options you can customize:

Message Format ENS messages are available in four different formats. The standard HTML format displays the event message in a nice webpage-like format, with an image of the globe with the event location marked. Most users will want to choose HTML format. For information on the other formats, see Message Format details below.

Day Begins and Day Ends Day and night time windows are associated with each individual email address. 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. For an email account, set the start and end times both to 00:00 in order to have your daytime magnitude limit in place 24 hours.

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 Account Preferences tab on the main page.

The purpose of having your time zone in the system is so that messages sent to you can include the time the earthquake occurred in your time zone. If the time is off by one hour, it is probably because your time zone observes Daylight Saving or Summer Time. The time zone setting in your account is based on how far east or west you are from the Prime Meridian in Greenwich, England. The adoption of Summer Time is a politically determined thing. Since our system does not know your address or even what country you are in, it has no way of knowing whether or not your area observes Summer Time. If your area observes Summer Time, you can compensate for this by changing your time zone one hour to the east during Summer Time.

Using this list, you can change the options for the address. You must click Save after making changes.

To remove an address from your account, simply click the Delete button. You will be presented with a dialog box asking you if you really want to delete the address.

Register a new address

To associate another email address with your ENS account, click the Add Another Email Address button located below the list of addresses. You will be presented with a popup message like the following:

Register new address dialog box

Replaces This option is only necessary if you want to replace an existing address.

The options in this dialog box are explained above under the Managing Your Email Addresses header.

Click Register Address to submit the form. You will need to check your email to receive your confirmation number.

Confirm new address box

This number needs to be entered in the box on the main page. You may need to refresh the page to see the confirmation box. If you cannot get this box to appear, you can confirm the email with this confirmation page.

 


Managing Your Account

Account preferences panel

ENS allows you to customize several settings related to your account. Click on the Account Preferences tab to see the list of settings. They are described below:

Your Name First and last name.

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?

Preferred Language English or Spanish.

Your Affiliation Please indicate your interest in earthquake notification. If it isn't listed, write it into the “Other” box.

Aftershock Exclusion 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…

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

NOTE: Aftershock exclusion is turned on by default for new ENS accounts. If you do not want to use this feature, you must turn it off.

Receive updates for events?

event updates

Occasionally ENS will send messages with an incorrect magnitude. In cases where the magnitude changes by more than 0.4 or the location changes by more than 0.5 degrees of latitude or longitude, the system will send out an update or deletion message to all users who received the original message. If you don't want to receive these updates, choose "No". If an event is deleted you will always receive the delete notification if the original magnitude meets your other setting thresholds.

Defer notifications during night hours?

event updates

Each profile has an associated day and night magnitude threshold. If an earthquake happens at night above the 'night' threshold, a message will be sent to you. If the magnitude is above the 'day' threshold, but below the 'night' level, having this option set will cause the system to generate a message to you, which will be held until the following morning. This setting also applies to event updates. Select "Yes" to delay notifications.

NOTE: This option is intended for profiles that generate messages sent to phones or pagers.

Password/Retype Password To change your password, enter a new password twice, once in each box.

Click Save Changes to store your new settings. A success message should appear below the button when your changes have been saved.

Note that you cannot change your Username.

Vacation Option

Vacation options

ENS allows you to disable event notifications for a period of time. This feature is a simple way to suspend notifications for all profiles and all addresses associated with your account. Note that ENS does not save messages for you during your vacation, so you will not receive a backlog of notifications when your vacation ends.

Unsubscribe

You can Unsubscribe at any time from the Account Preferences page. Additionally, you can unsubscribe individual email addresses by replying to an earthquake message with a one-line, plain-text message containing the word 'STOP'. The system will automatically remove that address from the system. If your message contains extra text, or is a non-plain-text character encoding, the administrator will have to remmove it by hand, which may take several days.

Unsubscribe button

If you click the “Unsubscribe” button, the following message will appear:

Confirm unsubscribe

If you click “Yes, unsubscribe”, you will get the following confirmation message:

confirm unsubscribe message

Click OK to return to the ENS homepage.

If you are having trouble unsubscribing, please contact the ENS administrator: ensadmin@ens.usgs.gov

NOTE: All ENS earthquake messages contain a numeric identifier code associated with the email address they are being sent to. Long-form messages have an identifier code at the end of the subject like:

2010-03-17 17:01:01 (M3.9) BAJA CALIFORNIA, MEXICO 32.3 -115.3 (31b86)

Short-form ENS messages have an identifier code at the end, like this:

M6.2 21:44 5/29 -30.2 -178.1 105km SSW of Raoul Island, Kermadec Islands US c000yra7 31b86

The '31b86' is the identifier code.

If you need assistance from the ENS administrator, please forward one of these identifier codes so that the administrator can find your account in the system.


ENS Glossary of Terms

Active

Use this to mark this profile 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 profile, all addresses are selected by default. If there is an address you don't want associated with this profile, 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…

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 1017309
	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:
	http://earthquake.usgs.gov/recenteqsUS/Quakes/ld1017309.htm
	or
	http://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 superceded 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:

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.

Profile Name

This is an optional field where you can enter a name for your profile. The name is used to identify the profile 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”.


DISCLAIMER

The earthquake information delivered through the Earthquake Notification Service (ENS) is preliminary. Subsequent review usually results in some revision to the data, and all users are advised to check the USGS earthquake program pages at http://earthquake.usgs.gov for updates. Data users are cautioned to consider carefully the provisional nature of the information before using it for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Earthquakes are a common occurrence, and many are either not large enough to cause damage or not located sufficiently close to populations centers to produce damage. E-mail alerts sent through ENS do not imply an impending threat.

ENS is an informational tool and NOT a robust earthquake or tsunami warning system. The USGS does not produce tsunami warnings. For the information about tsunamis, please refer to the information given in the NOAA website http://tsunami.gov/.

On a global basis, earthquakes of magnitude 5.0 or greater are generally reviewed and distributed by ENS within 2 hours or their occurrence. Some events of magnitude 5.0 to 6.0 in remote parts of the world, especially on mid-ocean ridges in parts of the Southern Hemisphere, may not be distributed until 24 hours after their occurrence. Within the US, widely felt earthquakes are generally distributed within 5 minutes. Additionally, processing and sending the messages typically takes 30 minutes. The USGS cannot guarantee the receipt or timeliness of an e-mail message after it has been sent.

If numerous bounced messages are received from your account, the automated system will not remove your address from the ENS mailing list. If that should happen, your mail profiles will be marked 'inactive' and the system will stop sending you mail. If you fix your address and you still want to receive e-mails, just log in and mark your profiles active.

The events which have been located by the USGS and contributing agencies should not be considered to be a complete list of ALL events M2.5+ in the US and adjacent areas and especially should not be considered to be complete lists of ALL events M4.0+ in the World. The World Data Center for Seismology, Denver (a part of the USGS National Earthquake Information Center) continues to receive data from observatories throughout the world for several months after the events occurred, and using those data, adds new events and revises existing events in later publications. For a description of these later publications and the data available, see Scientific Data.

Please address unresolved mailing list issues to: ensadmin@ens.usgs.gov.