- TrueReels
- Series
- Lituya Bay
- Episode 7
Lituya Bay: One Wave. 1,720 Feet. Survivors.Episode 71:39
The Air Cavity Inside the Megatsunami
A laboratory bay reveals the hidden pocket of air that helped turn a local landslide into a record-setting splash.
Watch it in the appThis episode needs All Access, from $4.99 a week.
Transcript
Water surged 1,740 feet up the opposite wall of Gilbert Inlet. The moment hangs beneath spray, shadow, and silence.
Lituya Bay is an ice-scoured tidal inlet in Alaska, 720 feet deep inside, with a 33-foot entrance sill.
The captain's anchor became hopelessly stuck.
About 40 million cubic yards of rock plunged into Gilbert Inlet.
The gravity wave moved at a speed probably between 97 and 130 miles per hour.
Landslide tsunamis hit locally with shorter wavelengths and larger amplitudes than earthquake tsunamis.
In a physical model, the impossible wave became something researchers could watch.
A laboratory model reproduced the exceptional Lituya Bay run-up.
Researchers found a large air cavity forming during the landslide impact.
The model showed trapped air could displace more water than the rock alone.
The maximum splash reached about 1,719 feet (524 meters) up the opposite hill.
Howard G. Ulrich later recalled the sound that followed: After about a minute of shaking, I heard a roar.
The real 1958 event did not penetrate into the ocean.
A wave can stay local, yet still erase the boundary between water and mountain.
Miller linked frequent giant waves to steep slopes, deep water, rainfall, and freeze-thaw.
Where it leaves off
The large air cavity solved how the megatsunami climbed the mountain—but Miller's final conclusion was that Lituya Bay was already preparing to do it again…
Sources
- ALASKA STATE LIBRARYdggs.alaska.govprimary
- 60 years ago: The 1958 earthquake and Lituya Bay megatsunami | Alaska Earthquake Centerearthquake.alaska.edusecondary
- LANDSLIDE TSUNAMISnctr.pmel.noaa.govsecondary
The whole series is in the app.
Download on the App StoreAll Access is $4.99 a week, $14.99 a month or $39.99 a year. The annual plan starts with three days free.