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.

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

The banner and stop light indicate the highest level of alert at present for any of the regions covered by the U.S. Tsunami Warning Centers. It also provides basic earthquake information on the last earthquake that prompted a message to be issued by either center.

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

A list of all the tsunami messages and the associated alert levels, where applicable, is below the map. You may need to scroll down to see this list.

What do the alert colors on the map mean?

The following colors are used on the Alert layer to indicate the present level of alert. No color indicates no tsunami warning, advisory, watch, or threat at this time.

Tsunami Warning—Red
Tsunami Advisory—Orange
Tsunami Watch—Yellow
Tsunami Threat—Purple

Tsunami Message Definitions

What do the various icons on the map mean?

The Messages and Earthquake layers are automatically selected. Icons used in these layers are shown below. Click on the icons on the map for more information.

Location of most recent earthquake
- Icon color represents current advisory level for this earthquake
Tsunami Warning Boundaries
Tsunami Advisory Boundaries
Tsunami Watch Boundaries
Tsunami Threat

Tsunami Message Definitions

Additional information is available on other layers. Icons used in these layers are shown below. Click on the icons on the map for more information.

Previous earthquakes shown when Previous 40 is selected
Previous earthquakes shown on Previous Messages Page
Observations
Forecasts
Water-Level Stations
DART Systems
More Information Available (shown in pop ups)

Tsunami Message Definitions

What do the various messages mean?

Tsunami messages are defined on the Message Definitions page.

What is on the Alert layer?

The Alert layer is automatically selected and displays (at a high level) the coastal areas that are under active tsunami warnings, advisories, and watches (in the United States, Canada, and the U.S. British Virgin Islands) and tsunami threats (international partners). The coasts under an alert or threat are shaded using the corresponding colors: warning—red, advisory—orange, watch—yellow, threat—purple. For continental U.S. and Canadian coasts, the boundaries of the alerts are also marked with similarly colored boundary icons. For U.S. and Canadian coasts, zoom in on the map to get a better view of alert zones. Alert zones are defined by NWS marine and/or public zones (as depicted in the Public Forecast Zone Maps). Entire forecast zones will be 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.

What is on the Observations layer?

If a tsunami is observed on a water-level gauge, it will be shown on the map when the Observations layer check box is checked. Icons will show where the tsunami has been observed. Click on the icons for information about each observation. Information includes location, observed height, and time and date of observation given in the default browser time.

What is on the Forecasts layer?

When The Tsunami Warning Centers issue forecasts for certain sites, they can be displayed by selecting the Forecasts layer check box. Icons will show sites for which forecasts are available. Click on the icons for information about each location’s forecast. Information includes location, forecasted arrival date and time, and forecasted wave height , if available.

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..

What is on the DART System layer?

The DART System 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..

What is on the Travel Time layer?

In major events, a tsunami travel time layer may be available when the Travel Time layer check box is checked. Travel time contours are shown in one hour increments for the entire basin involved.

Why am I unable to select some of the layers?

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

What is on the Observations and Forecasts link?

The Observations and Forecasts page includes information about each 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. Observed and forecast heights in the table that meet the criteria established for tsunami advisories or warnings will be highlighted with the corresponding color. For example, any height greater than 0.3 meters and less than 1.0 meters will be marked in orange (advisory), while any height greater than, or equal to 1.0 meters will be marked in red (warning).

What does the Energy Map show?

The Energy Map shows the maximum tsunami forecast heights throughout the ocean basin when a forecast is available. This information provides information on general directivity of the tsunami energy. See example below.

What does the Travel Time Map show?

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.