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Guide

Tsunami: what to do on the Gulf

Checked September 28, 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, Texas A&M University at Galveston’s Tsunami Research Group, the Texas Division of Emergency Management, TxDOT and the county and city 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. Texas A&M University at Galveston’s 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. It adds that 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 lists only a handful of entries for the Texas coast, and they are small. The largest is from May 2, 1922: a train of three waves with an amplitude of 0.64 metres — about two feet — on the Galveston tide gauge. Its cause is uncertain; NOAA’s notes say it was probably a source in the Gulf itself, and that a landslide or slow earthquake off Galveston “would not have been felt.” That is the lesson worth keeping: here, the sea may be the only warning.

The maps

The Tsunami Research Group has drawn tsunami inundation maps for South Padre Island, Port Aransas, Corpus Christi, Galveston, Jamaica Beach, San Luis Pass and Freeport. Each shows the combined maximum flooding from seven modelled underwater landslides, and each says what it is for: it portrays “the worst case scenario”, gives no estimate of how often such an event happens, and is for local evacuation planning only — “not intended for site-specific or land-use purposes.” Read one as the outer edge of what is possible, not as a forecast.

What the alert levels mean

In the warning centre’s own definitions and recommended actions:

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 and city systems, and those you have to register for.

The sign-ups that could be confirmed for the counties on these boards, south to north (read September 28, 2026):

For Willacy, Kleberg, San Patricio, Refugio, Jackson, Matagorda and Brazoria counties no public sign-up page could be confirmed, so none is listed; ask the county’s office of emergency management.

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.

Two things are worth doing before a storm. TxDOT publishes hurricane evacuation routes for the whole coast, Beaumont to Brownsville. And the Texas Division of Emergency Management runs the State of Texas Emergency Assistance Registry (STEAR), a free registry that tells local planners who may need help, such as transport, to evacuate; the division is clear that registering does not guarantee a service.

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