10 Critical Tsunami Facts Hawai‘i Must Know After Japan’s Megaquake Alert

As Japan braces for a potential catastrophic earthquake and tsunami, Hawai‘i faces its own risks from these deadly natural disasters. Here’s what island residents need to know to stay safe.

1. Tsunamis Travel Faster Than You Think

A tsunami can race across the ocean at speeds exceeding 500 mph – as fast as a jet plane. From Japan, waves could reach Hawai‘i in as little as 5-7 hours.

2. The First Wave Isn’t Always the Biggest

Danger often comes in multiple waves, with later surges sometimes being more powerful than the initial impact. Never assume the danger has passed after one wave.

3. Hawai‘i’s Warning System Has Limits

• Tsunami sirens are only meant for outdoor alerts
• Cell phone alerts may be delayed during high traffic
• Radio and TV remain the most reliable warning sources

4. Evacuation Zones Aren’t Just for Beachfront Properties

Many inland areas in Hawai‘i are still at risk due to wave run-up and flooding potential. Know your zone before disaster strikes.

5. “Blue Zone” Doesn’t Mean Safe Zone

Areas marked in blue on tsunami maps indicate potential inundation areas, but actual flooding can extend beyond these boundaries in extreme events.

6. Boats Need Special Precautions

Mariners should head to deep water (>100 fathoms) during tsunami warnings as waves are less dangerous offshore than near the coast.

7. Tsunami Survivors Report Strange Ocean Behavior

1. Sudden water recession exposing seafloor
2. Unusual waves breaking in patterns
3. Loud roaring sounds from the ocean

8. Preparation Goes Beyond Evacuation Routes

Every household should have:

• 72-hour emergency kit
• Important documents in waterproof container
• Communication plan for separated family members

9. Historical Patterns Show Hawai‘i’s Vulnerability

The islands have experienced devastating tsunamis in 1946, 1952, 1957, 1960, and 1964, with the 1946 event causing 159 deaths.

10. Climate Change Is Making Tsunamis More Dangerous

Rising sea levels mean future tsunamis could penetrate farther inland than current maps predict, putting more areas at risk.

What do you think?

• Should Hawai‘i invest more in tsunami barriers like Japan has?
• Are current evacuation zones properly marked in your community?
• Would you risk staying behind to protect your property if a tsunami warning sounded?
• Is the state doing enough to prepare for a mega-tsunami event?
• Should beachfront development be banned in high-risk tsunami zones?