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Prepping for a tsunami (Part 2): The warning signs

By The SHTF App Team

The ocean itself gives you a warning, if you know how to read it. The sudden recession of the sea, a loud roar from offshore, or a strong earthquake near the coast are all signals that a tsunami may be minutes away.

⚠️ The “Official Warning” trap. In a local tsunami, the official warning may not arrive in time. The earthquake IS the warning. If you feel strong shaking near the coast, do not wait for a siren, move to high ground immediately.

Disclaimer: The information provided in this article is for general informational and educational purposes only. It is not intended as, and should not be considered, professional or emergency-response advice. Always follow the instructions of local authorities and tsunami warning centers.

The Readiness Audit

Would you recognize a tsunami warning if you saw one?

  • 🟢 Green: You know the three natural warning signs, receding water, strong shaking, and a loud roar, and you’d act on any of them immediately.
  • 🟡 Yellow: You’d wait for an official siren or alert before doing anything.
  • 🔴 Red: You’d walk down to the beach to look at the receding water.

If you are Yellow or Red, execute Phase 1 immediately.

Phase 1: The Receding Sea (The Classic Sign)

Goal: Recognize the most famous, and most deadly, warning sign.

When a tsunami approaches, the trough of the wave often arrives first, pulling the water dramatically away from the shore.

  • The Sign: The ocean suddenly recedes, exposing the seafloor, stranded fish, and rocks that are normally underwater.
  • The Trap: This is fascinating, and people walk down to look. This is exactly how people die. The water that receded is about to come back as a wall.
  • The Action: If you see the water pull back dramatically, a tsunami is coming. You have minutes. Run to high ground immediately.

The Takeaway: Receding water is not a curiosity. It is a countdown. When you see it, you run.

Phase 2: The Earthquake (The First Warning)

Goal: Understand that the shaking is the warning.

In a local tsunami, the earthquake that triggers the wave is your first and most reliable warning.

  • The Sign: Strong ground shaking near the coast, shaking that makes it hard to stand, lasting 20 seconds or more.
  • The Action: Drop, cover, and hold on during the shaking. The moment it stops, move to high ground on foot. Do not wait for an official alert.
  • The Reason: The tsunami may arrive in minutes. The official warning may not come in time. The earthquake is the warning.

The Takeaway: If you feel strong shaking near the coast, the clock has already started. Move to high ground the moment the shaking stops.

Phase 3: The Roar (The Audible Sign)

Goal: Recognize the sound of an approaching tsunami.

A tsunami makes a distinctive sound as it approaches, a sound survivors consistently describe.

  • The Sign: A loud roar, like a freight train or a jet engine, coming from offshore.
  • The Action: If you hear it, the wave is close. Move to high ground immediately. There is no time to investigate.
  • The Reason: By the time you can hear the roar, the wave is nearly on top of you.

The Takeaway: A roar from the ocean is not the wind. It is the wave. Run.

Phase 4: The Official Warning (The Backup)

Goal: Understand the role of official alerts.

Official tsunami warnings are valuable, but they are a backup, not a primary defense.

  • The System: Tsunami warning centers monitor earthquakes and issue alerts via sirens, radio, TV, and Wireless Emergency Alerts.
  • The Limit: In a local tsunami, the official warning may arrive after the wave. The natural signs are faster.
  • The Rule: Treat official warnings as confirmation, not as your only trigger. The natural signs, shaking, receding water, the roar, are your primary triggers.

The Takeaway: Official warnings are a safety net. The natural signs are your first line of defense.

The Essential Kit Checklist

  • The Knowledge: Teach every family member the three natural warning signs.
  • The Drill: Practice the response, “if the ground shakes, we move to high ground.”
  • The Route: Confirm your evacuation route and walk it once this season.
  • The Alerts: Enable Wireless Emergency Alerts on your phone.

Scenario Planner (Contingencies)

“The water receded and everyone is walking out to look.” The trap: following the crowd toward the danger. The fix: be the one who runs the other way. Receding water is a countdown, not a spectacle. Move to high ground and warn others as you go.

“I felt shaking, but it was mild, so I stayed put.” The trap: underestimating a mild quake. The fix: even moderate shaking can trigger a tsunami if it’s offshore and long-duration. If you’re near the coast and feel shaking that lasts 20 seconds or more, evacuate. It’s better to be wrong on high ground than right at sea level.