For many, the deadly 2004 tsunami in Thailand – or the movie it inspired – was the first they'd
heard of anything bigger than the dreaded tidal wave. But the U.S. gets tsunamis,
too, including the largest wave on record.
The average disaster movie portrays tsunamis as gigantic walls of ocean water that obliterate
cities and towns in an instant, and rightly so. Tsunamis are indeed massive waves of
ocean water that cause tremendous destruction and death. A naturally occurring phenomenon,
tsunamis aren't influenced by the wind or the moon, as typical ocean water tends to be. Instead,
tsunamis are an after-effect of a major natural disaster.
According to the National Ocean Service, tsunamis — a word that blends the Japanese
words for "harbor" and "wave" — are most often caused by either an underwater volcanic eruption
or earthquake. The depth of the ocean where the tsunami originates determines how fast
it will travel across the water and how high the waves will crest. The deeper the water,
the faster the tsunami moves, sometimes clocking speeds close to jet planes, or 500 miles an hour.
The largest tsunami ever recorded happened in 1958 in Lituya Bay, Alaska. Located in the southeastern
portion of the state, Lituya Bay is actually a fjord — a long narrow body of water generally
located between high cliffs. It was discovered in 1786 by the French explorer Jean-François de
Galaup La Pérouse. Due to its geographical location, the area is naturally prone to
earthquakes and high tides that, when combined, make the perfect recipe for tsunamis to happen.
Given the geographical characteristics of Lituya Bay, the 1958 mega-tsunami was not the first event
of its type in the area. In 1899, an earthquake in Lituya Bay caused a tsunami that killed five
people and destroyed an indigenous village. Nearly 40 years later, in 1936, another tsunami
swallowed the small bay yet again. However, the mother of all tsunamis was yet to come.
On July 9, 1958, a 7.8 earthquake rocked Alaska along the Fairweather Fault. The
earthquake struck after 10 p.m. that night, and it was so intense that the inlet feeding into
the bay moved 20 feet in the opposite direction of the shore. Meanwhile, the earthquake caused
a rockslide that forced over 90 million tons of rock into the water. Vegetation was ripped from
the root at elevations of more than 1,700 feet, and millions of trees were uprooted.
Among the survivors was mountain climber Howard
Ulrich, who witnessed the event with his 8-year-old son from a fishing boat on Lituya Bay.
"What I observed was like an atomic explosion."
Ulrich described the 1,720-foot wave as a "wall
of water." He told The Daily Astorian that it was as if:
"You're looking at death, and this was exactly my first thought."
"He threw me a life preserver and said, "Son, start praying."
Ulrich remembered the moment to The Daily Astorian, recalling his exact words:
"God what an awful sight. [...] Something like the end of the world."
"We were swept over the land and up above the
trees. That's where I assumed that we were going to end up."
The damage to the Lituya Bay area was extensive. But despite all the destruction,
only five people died in the catastrophe. Three were killed when the first wave of
water drove Khantaak Island into the bay, 100 feet below sea level.
Two others died as the massive wave sank their ship, which was stationed in the bay.
"Has there been a first-hand report from any of the boats up there, over."
"If there's any other boats in here,
I don't think they made it. I don't see 'em, and I don't hear 'em."
But two people were miraculously rescued as they clung to a dinghy after their boat sank.
Scientists struggled to determine what could have caused the 1,720-foot monster. It was later
discovered that, during the rock slide, a 300 foot thick slab of rock that measured 2,400 by
3,000 feet crashed into the inlet that fed the bay, triggering the tsunami.
As the giant rock fell thousands of feet into the water, it set off an incredibly destructive chain
of events. The Western States Seismic Policy Council compared the impact to the effect of
a sizable asteroid crash landing. According to the U.S. Tsunami Warning System, tsunamis
which occur near their source happen twice a year, while tsunamis that wreak havoc in other
locations from where they originate happen about twice per decade. All told, in the 20th century,
34 tsunamis killed over 500 people in the U.S. and caused $1.7 billion in damages.