Map FAQ


This page focuses on how to read the tsunami.gov map page. Answers to other tsunami questions are on the Tsunami Frequently Asked Questions page.

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What does the banner at the top of the page show?

The information in the banner corresponds to the message that communicates the greatest estimated danger posed by a currently active event in any of the regions covered by the U.S. Tsunami Warning Centers. If there is not currently an active event, the banner provides basic earthquake information about the last earthquake that prompted a message to be issued by either center.

Banner colors are associated with message type (alerts and threat) as shown below.

 Tsunami Warning—Red

 Tsunami Advisory—Orange

 Tsunami Watch—Yellow

 Tsunami Information Statement—Green

 Tsunami Threat—Purple

There may be other important messages associated with an active event. See the next two questions to learn more.

Tsunami Message Definitions


Where can I see all of the tsunami messages for an event?

For the United States, Canada, and the British Virgin Islands, all the active tsunami alerts associated with an event are listed below the map. You may need to scroll down to see them. Alert icons precede text that states where the alerts/threats are in effect and the time and date of issuance (default browser time).

Tsunami Message Definitions

The Previous 40 Tsunami Messages table beneath the list of active alerts contains the last 40 tsunami messages issued by the U.S. Tsunami Warning Centers, including tsunami threat messages for international partners. A plus sign (+) in the Origin Time column means that there are multiple messages. Click on the plus sign (+) to see all the messages.


What is on the Alert/Threats layer?

The Alerts/Threats layer is automatically selected and provides information about currently active messages.

  • If an actionable alert (warning, advisory, watch) is issued for the United States or Canada, the coastlines under alert are highlighted in the corresponding color. For continental U.S. and Canadian coasts, the alert boundaries are also marked with similarly colored pin icons. Zoom in on the map to get a better view of the areas under alert. For U.S. coasts, these “forecast zones” are defined by NWS marine and/or public zones as depicted in the Public Forecast Zone Maps. Entire forecast zones are colored rather than expected inundation zones. Forecast zones extend well-inland from the expected inundation zone. This means that some inland areas may appear to be included in an alert, but that does NOT mean that local authorities are suggesting evacuation from those areas. If in doubt, check with your local emergency management agency, NWS Weather Forecast Office, or police.
  • If a tsunami threat is issued for international partners, the countries under the threat will be marked with a purple pin icon. National authorities will determine the appropriate level of alert for each country and may issue additional or more refined information and instructions.

Click on the icons on the map for more information.

Message Type Coastal Extent Alert Boundaries Threat Location
Tsunami Warning—Redn/a
Tsunami Advisory—Orangen/a
Tsunami Threat—Purplen/an/a
Tsunami Watch—Yellown/a

Tsunami Message Definitions


What do the various messages mean?

Tsunami messages are defined on the Tsunami Message Definitions page.


What is on the Earthquakes layer?

The Earthquakes layer is automatically selected and provides information about recent earthquakes for which a message(s) has been issued. If an earthquake occurs that meets certain criteria (Atlantic, Pacific), its location is shown with an earthquake icon. The icon color corresponds with the type of alert/threat (or the greatest level of alert associated with an event). If there are no active messages, the Earthquakes layer provides information about the most recent events of each product type issued in each basin for the last 10 days.

Click on the icons on the map for more information, and to learn even more about an earthquake, visit the U.S. Geological Survey’s website.

Tsunami Warning—Red
Tsunami Advisory—Orange
Tsunami Watch—Yellow
Information Statement OR Event Has Ended—Green
Tsunami Threat—Purple

Tsunami Message Definitions


What is on the Previous 40 Messages layer?

The Previous 40 Messages layer uses the icon shown below to display the earthquakes associated with the 40 most recent messages issued by one of the U.S. Tsunami Warning Centers. Click on the icon for more information about the earthquake’s location and magnitude and links to associated messages.

Source Location for Previous Message

What is on the Observations layer?

If a tsunami is observed on water-level gauges (DART systems and coastal water-level stations), icons on the Observations layer show the locations of the observations. Click on the icons for information about each observation. Information includes location, maximum observed height, and time and date of observation (default browser time). For more comprehensive observations information, click on the Observations and Forecasts link below the map.

Observation

What is on the Forecasts layer?

When the U.S. Tsunami Warning Centers issue forecasts for U.S. coasts, Canada, and the British Virgin Islands, icons on the Forecasts layer show where forecasts are available. Click on the icons for information about each location’s forecast. Information includes location, forecasted arrival date and time (default browser time), and forecasted wave height, if available. For more comprehensive forecast information, click on the Observations and Forecasts link below the map.

Forecast

What is on the Water-Level Stations layer?

The Water-Level Stations layer includes icons for coastal water-level stations around the world (not just those associated with a particular event). Click on the icons for information about each coastal water-level station’s location and, for U.S. stations, links to water-level data. To learn more about coastal water-level stations, see the Tsunami Frequently Asked Questions page.

Water-Level Stations

What is on the DART System layer?

The DART Systems layer includes icons for many of the available Deep-ocean Assessment and Reporting of Tsunami (DART) systems worldwide. Click on the icons for information about each DART system’s location and links to water-level data, when available. To learn more about DART systems, see the Tsunami Frequently Asked Questions page.

DART Systems

What is on the Travel Time layer?

In major events, a tsunami Travel Time layer may be available that displays travel time contours in one-hour increments for the entire basin involved.


Why am I unable to select some of the layers?

Most earthquakes do not generate tsunamis, thus the Observations, Forecasts, and Travel Time layers may not be populated with information. In these instances, you are not able to select these layers. When a tsunami is occurring, these layers are activated as soon as information becomes available.


What is on the Observations and Forecasts link?

The Observations and Forecasts link goes to a page that includes information about an event, including source location, magnitude, depth, origin time, and message issue time. Observations (observed time and height) and forecasts (predicted height and arrival times) are provided in the table when available.


What does the Energy Map show?

When a forecast is available, an Energy Map shows the maximum tsunami forecast heights throughout the ocean basin and provides information on general directivity of the tsunami energy. See example below.


What does the Travel Time Map show?

When a tsunami is expected, the Travel Time Map shows expected travel time (in hours) from the tsunami’s source to locations throughout the ocean basin, when available. Contours on the map represent 30-minute intervals. Each change in color shade of a contour line is a one-hour mark. See example below.


What is a CAP File?

The CAP (Common Alerting Protocol) file provides information on the tsunami message in a format intended for use by those involved with emergency message transmission.


What is a TEX File?

The TEX (Tsunami Event XML) file is intended for those who need to automate tsunami information dissemination.


How can I get information about previous messages that are no longer displayed on the home page?

The Previous Tsunami Messages page provides access to a searchable database of previous messages. A search results in a page with a map and a table of previous messages that meet the search parameters. Associated earthquakes are shown on the map with the icon below. A plus sign (+) in the table’s Origin Time column means that there are multiple messages available. Click on the plus sign (+) to see all the messages.

Source Location for Previous Message