Tsunami 101 | National Geographic

Summary

Tsunamis are powerful, destructive waves caused by underwater earthquakes, resulting from the shifting of tectonic plates. These waves travel rapidly in deep water, but as they reach shallow coasts, their speed decreases, and their height increases, leading to massive destruction. Unlike regular waves, tsunami waves strike as an unbroken wall of water, flooding areas far inland. The deadliest tsunami recorded occurred in 2004, killing over 200,000 people. Modern warning systems like the Pacific Tsunami Warning Center aim to prevent similar disasters by monitoring seismic activity and advising affected regions to evacuate to higher ground.

Takeaways

• 😀 Tsunamis are caused by underwater earthquakes, triggered when tectonic plates shift and displace large amounts of water.
• 🌊 In deep water, tsunami waves travel at speeds up to 500 miles per hour, but their height is minimal.
• 🏖️ When tsunami waves approach shallow waters, friction with the ocean floor causes them to slow down and increase in height.
• 🌊 Tsunami waves do not break like ordinary waves but come in as a massive wall of water, flooding coastal areas.
• ⚠️ Tsunamis can reach as far as a mile inland, causing significant damage to buildings and infrastructure.
• 🌊 The receding water of a tsunami can cause additional destruction, pulling debris back into the ocean.
• ⏱️ Tsunamis typically consist of multiple waves that strike at intervals of 10 to 60 minutes, often catching survivors off guard.
• 🌀 The 2004 tsunami, triggered by an earthquake near Indonesia, killed over 200,000 people and devastated coastal cities across the Indian Ocean.
• 📡 The Pacific Tsunami Warning Center in Honolulu monitors global seismic activity to predict and warn coastal areas of potential tsunamis.
• 🚨 In the event of a tsunami warning, the advice is to move to higher ground, wait for confirmation that the tsunami has passed, and prepare for the aftermath.

Q & A

What causes a tsunami?

A tsunami is caused by an earthquake, particularly when two tectonic plates push together. The resulting earthquake sends a burst of energy through the ocean, displacing a large amount of water and generating waves.

How fast do tsunami waves travel in deep water?

In deep water, tsunami waves can travel at speeds up to 500 miles per hour, though their height is only a few feet, which makes them hard to detect from a ship.

What happens when tsunami waves enter shallow waters?

As tsunami waves enter shallow waters, the friction with the ocean floor slows them down and causes their height to increase dramatically, making them more dangerous when they reach the coast.

What is the impact of a tsunami wave on the coastline?

A tsunami wave crashes onto the coastline as a massive wall of water, advancing with destructive force and potentially reaching up to a mile inland, causing significant damage.

How does a tsunami cause additional damage after the initial wave?

In addition to the initial wave, a tsunami causes more damage when the water recedes, dragging everything in its path back underwater, which can destroy buildings, infrastructure, and more.

How many waves typically make up a tsunami?

Most tsunamis consist of multiple waves, which can arrive anywhere from 10 to 60 minutes after the first wave, leading to additional destruction when survivors think the danger has passed.

What was the deadliest tsunami ever recorded?

The deadliest tsunami ever recorded occurred in December 2004, triggered by an earthquake off the coast of Indonesia. It surged across the Indian Ocean, reaching as far as the coast of Africa and causing over 200,000 deaths.

How do scientists monitor and warn about potential tsunamis?

Scientists at the Pacific Tsunami Warning Center in Honolulu monitor seismic activity and earthquakes around the world. If a large earthquake occurs, they issue alerts to coastal areas that may be affected by a tsunami.

What should people do in case of a tsunami warning?

If a tsunami warning is issued, people should move to higher ground, wait for confirmation that the tsunami has passed, and be prepared to deal with the aftermath, including any destruction left by the waves.

Why is Japan particularly vulnerable to tsunamis?

Japan is particularly vulnerable to tsunamis due to its location across the edges of four tectonic plates, where most earthquakes, the primary cause of tsunamis, occur.