Guide
Tsunami: what to do on the Gulf
Checked September 29, 2026 against the National Tsunami Warning Center, the National Weather Service, the National Hurricane Center, NOAA’s National Centers for Environmental Information, the U.S. Geological Survey, the TAMUG Tsunami Research Group, and the Hancock, Harrison and Jackson county alert pages linked below.
The Tsunami tile repeats what the National Tsunami Warning Center has said. A tsunami on this coast is rare, and this page says plainly what is and is not known about one, what each alert level means, how to get your county’s alerts, and why the water that usually does the harm here comes from a hurricane instead.
If the Gulf does something strange, go to high ground or inland now. The National Weather Service’s natural warnings: a strong or long earthquake; the sea rising like “a fast-rising flood or a wall of water”, or draining away to show the bottom; or a loud roar from the water. Any of those means a tsunami “could arrive within minutes.” Do not wait for an official warning, a phone alert or this website.
Who warns this coast
The National Tsunami Warning Center in Palmer, Alaska, issues tsunami messages for this coast. NOAA gives its area as “coastlines along the continental United States, Alaska, and Canada”, and that includes the Gulf. Its first messages are built from the earthquake’s location, depth and magnitude, often before any wave has been measured, and they are updated, upgraded or cancelled as more information comes in.
What is actually known about the Gulf
The U.S. Geological Survey’s summary is short: tsunamis on the Atlantic and Gulf coasts “are rare, but the risks associated with these natural hazards are high.” The source studied most is not an earthquake fault but an underwater landslide on the steep continental slope far offshore. The TAMUG Tsunami Research Group, which maps the Gulf’s hazard for NOAA’s National Tsunami Hazard Mitigation Program, writes that assessments by the USGS and the programme “identified underwater landslides as the primary potential source”, that the probability of a massive one is “quite low”, and that the large ancient slides were probably active more than 7,000 years ago. Its preliminary modelling of sources outside the Gulf, such as earthquakes along the Caribbean plate boundary, has indicated “a very low threat”.
The record agrees. NOAA’s historical tsunami database, searched for Mississippi, lists no entries: no tsunami and no reading of one anywhere on this coast. Nothing in that record is a warning to wait for, which is why the sea’s own signs above come first.
The map
The Tsunami Research Group has drawn tsunami inundation maps for a series of Gulf towns, each showing the worst case its modelled landslides could produce. None of them is on the Mississippi coast, so there is no tsunami inundation map for these three counties to point you to.
What the alert levels mean
In the warning centre’s own definitions and recommended actions:
- Warning. Issued when “a tsunami with the potential to generate widespread inundation is imminent, expected, or occurring.” Move to high ground or inland. The centre says the danger may continue for several hours after the first arrival.
- Advisory. A tsunami that can bring “strong currents or waves dangerous to those in or very near the water.” Stay out of the water and away from beaches and waterways. Officials may close beaches and clear harbours and marinas.
- Watch. Issued when “a tsunami may later impact the watch area.” Stay tuned and be prepared to act.
- Information statement. An earthquake or tsunami “has occurred of interest”, with no threat or none yet determined. No action is suggested.
Getting an official alert
Wireless Emergency Alerts come to a capable phone with nothing to sign up for — the weather service’s words are “No signup is required!” — and it sends them for tsunami warnings, hurricanes and storm surge. They are short. The longer local messages come from county systems, and those you have to register for.
The county sign-ups, west to east (read September 29, 2026):
- Hancock: CodeRED, on the county Emergency Management and Fire Department page, which says it “will notify you in the event of an emergency situation or critical community alert through a phone call, text message, email, or mobile app notification.”
- Harrison: the county’s Code Red Emergency Alert program, registered for on its E-Notify page.
- Jackson: the Regroup Notification System, on the county’s Emergency Notifications page, for email, text or voice alerts.
If you are not sure which system covers your address, ask your county’s emergency management office.
The water that usually does the harm here
On this coast the dangerous rise in the sea is almost always storm surge from a tropical storm or hurricane. The National Hurricane Center calls storm surge “currently the leading cause of fatalities from hurricanes” and says all locations on the Gulf coast are vulnerable to it. That is the Weather tile’s job and the weather service’s storm surge and hurricane warnings’, not this tile’s. Before a storm, the county emergency management office is the one that orders evacuations and names the routes and shelters.
Sources
- National Tsunami Warning Center, message definitions — the four alert levels and their actions
- NOAA Tsunami Program, forecast and warning — the warning centres’ areas of responsibility
- National Weather Service, during a tsunami — the natural warnings
- U.S. Geological Survey, Atlantic and Gulf submarine landslides and tsunami hazards project
- TAMUG Tsunami Research Group, National Tsunami Hazard Mitigation Program in the Gulf — the sources, the probability, and the list of inundation maps
- NOAA National Centers for Environmental Information, global historical tsunami database — searched for Mississippi: no entries
- National Weather Service, Wireless Emergency Alerts
- National Hurricane Center, storm surge overview
- County alert pages: as linked above