1958 Lituya Bay Tsunami
Description
On July 10, 1958, a magnitude 7.7 earthquake occurred on the Fairweather Fault in southeast
Alaska. It caused significant geologic changes in the region, including areas that experienced uplift
and subsidence. It also caused a rockfall in Lituya Bay that generated a wave with a maximum
height of 1,720 feet – the world’s largest recorded tsunami.
Impact
A total of five people were killed in the
event: three people died on Khantaak
Island at the mouth of Yakutat Bay when
the beach they were standing on subsided
100 feet below sea level; the other two died
when their boat was sunk by the tsunami at
Lituya Bay. Two other boats also were
anchored in the bay that night; those four
people managed to ride out the wave. Two
were rescued from a dinghy after their boat
sank, the others managed to pilot out of the
bay on their own power, but at great risk, as
the water continued to swirl unpredictably,
and was littered with millions of tree trunks
that had been ripped from the banks. Don
Above: A total of 4 ½ square miles of
dense forest was ripped out by the
tsunami. Credit: Colorado College
Left: Decades after the tsunami,
damage to the edges of the bay (the
light green areas) can clearly be seen
on this Landsat image. Credit:
Geology.com/NASA Landsat
Miller, a USGS geologist, had already documented a total of three other major tsunamis at this
location; he flew out to the site the next day, and although he was able to take photos from the air,
it was another three weeks before it was safe enough to land to document the destruction. He
found that all evidence of previous tsunamis had been destroyed by this one.
Scientists were puzzled for some time by the sheer size of the wave, because they could not identify
a mechanism that could have created such a massive reaction. Ultimately, it was discovered that a
piece of rock, 2,400 feet by 3,000 feet, and 300 feet thick, had dislodged from the face of the
northern wall of the inlet, and fallen 2,000 feet into the bay. In some respects, it created a similar
reaction to that which would have occurred if an asteroid had fallen into the water.
Lessons Learned
Unfortunately, there was nothing anyone could have done to prevent any of the five deaths. The
earthquake was so strong, and the tsunami came so quickly, that there was not time to get to a safe
place. It does, however, highlight the importance of documenting such events for posterity, and to
consider such extreme events when making development decisions for coastal areas in areas with
high seismicity or vulnerability to tsunamis.
References and Additional Resources
USC Tsunami Research Group: 1958 Lituya Bay Tsunami
http://www.usc.edu/dept/tsunamis/alaska/1958/webpages/index.html
Colorado College: “The Unfathomable Wave”
http://coloradocollege.edu/Dept/GY/Facultywebpages/Lituya Bay story.html
Disaster Pages of Dr. George PC: “The Mega-Tsunami of July 9, 1958 in Lituya Bay, Alaska”
http://www.drgeorgepc.com/Tsunami1958LituyaB.html
The Giant Waves of Lituya Bay
http://www.gi.alaska.edu/AlaskaScienceForum/article/giant-waves-lituya-bay
BBC Nature: Mega Tsunami – Alaskan Super Wave – Amazing Survival
http://www.youtube.com/watch?v=yN6EgMMrhdI