Giant Wave in Lituya Bay, Alaska
July 9th, 1958
Lituya Bay, on the northeast shore of the Gulf of Alaska, is an ice-scoured tidal inlet with a maximum depth of 720 feet and a sill depth, at the narrow entrance, of only 33 feet. The northeast-trending stem of the T-shaped bay, 7 miles long and as much as 2 miles wide, transects the narrow coastal lowland and foothills belt flanking the Fairweather Range of the St. Elias Mountains. The two arms at the head of the bay, Gilbert and Crillon Inlets, are part of a great trench along the Fairweather fault. Gentle slopes border the outer part of the bay, but the walls of the inner, fiordlike part rise steeply to altitudes of 2200 feet to more than 6000 feet.
In 1958 about 40 million cubic yards of rock, loosened either by displacement along the Fairweather fault or by the accompanying shaking, plunged into Gilbert Inlet from a maximum altitude of about 3000 feet on the steep northeast wall. This rockslide caused water to surge over the opposite wall of the inlet to a maximum altitude of 1740 feet, and generated a gravity wave that moved out the bay to the mouth at a speed probably between 97 and 130 miles per hour. Two of three fishing boats in the outer part of the bay were sunk, and two persons killed. ... Water was primarily responsible for destruction of the forest over a total area of 4 square miles, extending to a maximum altitude of 1720 feet and as much as 3600 feet in from the high-tide shoreline.
Three trolling boats, each about 40 feet long and with two persons aboard, were anchored in the outer part of Lituya Bay at the time of the wave on July 9. The Edrie rode out the wave inside the bay; the Badger was carried across La Chaussee Spit and wrecked on the outside; the Sunmore, under way near the entrance, was swamped by the wave and went down with her occupants. The wave reportedly was first sighted within 3 minutes after the earthquake was first felt, or, using the instrumentally determined origin time for the earthquake ..., between 10:16 and 10:19 pm on July 9, local time. This is about sunset at this latitude and time of year; the weather was clear, with high scattered clouds, and the head of the bay was clearly visible from boat level at the outer part of the bay. The tide was ebbing and at about plus 5 feet or less than a foot above mean tide stage in the bay.
Eyewitness Account of Howard G. Ulrich
Mr. Ulrich and his 7-year-old son, on the Edrie, entered Lituya Bay about 8:00 pm and anchorage in about 5 fathoms of water in a small cove on the south shore. Ulrich was awakened by the violent rocking of the boat, noted the time, and went on deck to watch the effects of the earthquake--described as violent shaking and heaving, followed by avalanching--in the mountains at the head of the bay. An estimated 2½ minutes after the earthquake was first felt, a deafening crash was heard at the head of the bay. According to Ulrich,
The wave definitely started in Gilbert Inlet, just before the end of the quake. It was not a wave at first. It was like an explosion, or a glacier sluff. The wave came out of the lower part, and looked like the smallest part of the whole thing. The wave did not go up 1800 feet, the water splashed there.
Ulrich continued to watch the progress of the wave until it reached his boat about 2½ to 3 minutes after it was first sighted. Being unable to get the anchor loose, he let out all of the chain (about 40 fathoms) and started the engine. Midway between the head of the bay and Cenotaph Island the wave appeared to be a straight wall of water possibly 100 feet high, extending from shore to shore. The wave was breaking as it came around the north side of the island, but on the south side it had a smooth, even crest. As it approached the Edri the wave front appeared very steep, and 50 to 75 feet high. No lowering or other disturbance of the water around the boat, other than vibration due to the earthquake, was noticed before the wave arrived. The anchor chain snapped as the boat rose with the wave. The boat was carried toward and probably over the south shore, and then, in the backwash, toward the center of the bay. The wave crest seemed to be only 25 to 50 feet wide, and the back slope less steep than the front.
After the giant wave passed the water surface returned to about normal level, but was very turbulent, with much sloshing back and forth from shore to shore and with steep, sharp waves up to 20 feet high. These waves, however, did not show any definite movement either toward the head or the mouth of the bay. After 25 to 30 minutes the bay became calm, although floating logs covered the water near the shores and were moving out toward the center and the entrance. After the first giant wave passed, Ulrich managed to keep the boat under control and went out the entrance at 11:00 pm on what seemed to be a normal ebb flow.
Eyewitness Account of William A. Swanson
Mr. and Mrs. Swanson on the Badger entered Lituya Bay about 9:00 pm, first going in as far as Cenotaph Island and then returning to Anchorage Cove on the north shore near the entrance, to anchor in about 4 fathoms of water near the Sunmore. Mr. Swanson was awakened by violent vibration of the boat, and noted the time on the clock in the pilot house. A little more than a minute after the shaking was first felt, but probably before the end of the earthquake, Swanson looked toward the head of the bay, past the north end of Cenotaph Island, and saw what he thought to be Lituya Glacier which had "risen in the air and moved forward so it was in sight. * * * It seemed to be solid, but was jumping and shaking. * * * Big cakes of ice were falling off the face of it and down into the water." After a little while "the glacier dropped back out of sight and there was a big wall of water going over the point" (the spur southwest of Gilbert Inlet). Swanson next noticed the wave climb up on the south shore near Mudslide Creek. As the wave passed Cenotaph Island it seemed to be about 50 feet high near the center of the bay and to slope up toward the sides. It passed the island about 2½ minutes after it was first sighted, and reached the Badger about 1½ minutes later. No lowering or other disturbance of the water around the boat was noticed before the wave arrived.
The Badger, still at anchor, was lifted up by the wave and carried across La Chaussee Spit, riding stern first just below the crest of the wave, like a surfboard. Swanson looked down on the trees growing on the spit, and believes that he was about two boat lengths (more than 80 feet) above their tops. The wave crest broke just outside the spit and the boat hit bottom and foundered some distance from the shore. Looking back 3 to 4 minutes after the boat hit bottom, Swanson saw water pouring over the spit, carrying logs and other debris. He does not know whether this was a continuation of the wave that carried the boat over the spit or a second wave. Mr. and Mrs. Swanson abandoned their boat in a small skiff, and were picked up by another fishing boat about 2 hours later.
-- USGS Prof Paper 354-C