🌊 Lesson 12: Recognizing the Warning Signs of a Tsunami 

1️⃣ What is a Tsunami?

✅ Definition

A tsunami is a series of large and powerful ocean waves caused by sudden movement of water, usually from:

• strong undersea earthquakes

• volcanic eruptions

• underwater landslides

• meteor impacts (rare)
  
  

📌 A tsunami is not a normal “big wave.”
It carries massive energy and can flood far inland.

2️⃣ What Causes a Tsunami?

Main cause: Underwater Earthquakes

When a fault under the sea suddenly moves, it pushes the seafloor up or down, displacing huge amounts of water.
That displaced water becomes fast-moving waves.

✅ Key fact:
If the earthquake is strong and long, and you are near the coast, a tsunami may follow.

3️⃣ Natural Warning Signs of an Impending Tsunami

Sometimes, nature gives warnings before official alerts arrive.
You must know these signs to protect yourself.

🚨 Sign 1: Strong or Long Earthquake Near the Coast

If you feel:

• a strong ground shaking, OR

• shaking that lasts 20 seconds or more,
  
  

👉 assume a tsunami is possible.

What to do immediately:
✅ Evacuate to higher ground once shaking stops.
Do not wait for an announcement.

🌊 Sign 2: Unusual Sea Behavior

This includes:

• the sea water suddenly pulling back far away from the shore (sea retreat)

• the shoreline “disappearing”

• fish or sea creatures left exposed on the beach
  
  

👉 This is a giant warning.

Meaning:
The retreating ocean may be gathering energy for a huge wave.

What to do immediately:
✅ Run to higher ground at once.

🌬️ Sign 3: Loud Roaring Sound from the Ocean

You may hear:

• a strong roaring, like a jet or thunder

• coming from the sea
  
  

This may mean a tsunami wave is approaching.

What to do immediately:
✅ Evacuate fast and warn others.

4️⃣ Why Early Warning and Quick Response Matter

Tsunamis can arrive within minutes after an earthquake.
Waiting too long means losing the chance to escape.

✅ Early response helps:

• reduce deaths and injuries

• prevent panic

• guide safer evacuation

• protect families and communities
  
  

First minutes matter most.

5️⃣ Basic Safety Actions During a Tsunami Alert

✅ If you are near the coast and feel strong shaking:

1. Duck, Cover, Hold during the quake

2. When shaking stops:
   ✅ Evacuate to higher ground immediately
   ✅ Move inland away from shore

3. Avoid bridges and coastal roads

4. Bring your Go Bag (if it’s nearby — don’t delay)
   
   

✅ If you hear a tsunami warning siren or official alert:

• follow evacuation routes

• do not return until declared safe

• expect multiple waves (the first may not be the biggest)
  
  

✅ If you see sea retreat or hear roaring waves:

• don’t take pictures

• don’t go near the shore

• RUN to higher ground

🧠 Summary / Takeaways

• A tsunami is a series of destructive waves, often caused by undersea earthquakes.
  
  

• Natural tsunami warning signs:
  ✅ strong/long earthquake near coast
  ✅ sudden sea retreat or unusual sea level
  ✅ loud roaring sound from ocean
  
  

• Quick evacuation saves lives.

• Always prioritize safety over waiting for official alerts.