Giant Waves in Lituya Bay, Alaska; USGS PP 354-C

Wave of July 9, 1958

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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The Giant Waves

Evidence

Two kinds of evidence testify to the occurrence of at least four giant waves in Lituya Bay: (a) direct observation of the waves, including the published, written, or oral accounts of eyewitnesses and possibly tidal gage records from elsewhere in the Gulf of Alaska; (b) effects that remain for later observation, mainly the destruction and transportation of vegetation, but also the erosion and transportation of unconsolidated deposits, destruction of marine life, and the destruction of works of man. The wave on July 9, 1958, and the waves on October 27, 1936, are documented beyond any doubt by both types of evidence. At least 1 and possibly 2 waves between 1854 and 1916 are indicated by trimlines shown on photographs taken from 1894 to 1929. These trimlines were largely destroyed by the 1936 wave, and were entirely gone after the 1958 wave. An oral report placing one of these waves in 1899 has not been substantiated. A wave in 1853 or 1854 is recorded in a trimline and a band of even-aged trees that was examined and mapped on the ground and dated by tree ring counts in 1952 'and 1953. Possible references to the 1853-54 wave in Indian legends have not been confirmed.

Wave On July 9, 1958

Setting And Sources Of Information

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 (fig. 15; pl. 3B). 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 of 06h15m51s G.c.t., July 10 (Tocher and Miller, 1959), between 10:16 and 10: 19 p. m. 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 (U. S. Coast and Geodetic Survey, 1957) or less than a foot above mean tide stage in the bay. The following eyewitness accounts are abstracted from articles published in newspapers and a magazine (Daily Alaska Empire, 1958a; Ulrich, 1958; Alaska Sportsman, 1958), from a personal interview with W. A. Swanson (oral communication, July 16, 1958) and correspondence with H. G. Ulrich (written communication, Oct. 24, 1958).

Figure 15. Map of Lituya Bay showing setting and effects of 1958 giant wave.

Eyewitness Accounts

Account Of Howard G. Ulrich

Mr. Ulrich and his 7-year-old son, on the Edrie, entered Lituya Bay about 8:00 p.m. and anchored in about 5 fathoms of water in a small cove on the south shore (fig. 15). 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 21/2 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 1,800 feet, the water splashed there.

Ulrich continued to watch the progress of the wave until it reached his boat about 21/2 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 Edrie 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 p.m. on what seemed to be a normal ebb flow.

Account of William A. Swanson

Mr. and Mrs. Swanson on the Badger entered Lituya Bay about 9:00 p.m., 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 (fig. 15). Mr. Swanson was wakened 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 the 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 21/2 minutes after it was first sighted, and reached the Badger about 11/2 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 2 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.

Other Observations on July 9

So far as is known to the writer, no other persons were near enough to Lituya Bay to see the wave, and no photographs were taken. A party of eight mountain climbers was camped in tents on the shore of Anchorage Cove, at the base of La Chaussee Spit, until about 8:00 p.m. on July 9, when they left in an amphibious airplane only a little more than 2 hours before the wave washed over their campsite. They did not notice any unusual noises or disturbance of the water in the bay, nor any foreshocks of the earthquake up to the time they left (Paddy Sherman, written communication, Oct. 20, 1958). At least one foreshock of the earthquake was felt on the morning of July 9 on boats between Lituya Bay and Cape Spencer (William Swanson, oral communication, July 16, 1958), and on land as far away as Juneau (E. L. Keithahn, written communication, Apr. 3, 1959).

Minor anomalous waves which may have been a direct result of the giant wave in Lituya Bay were recorded on the U.S. Coast and Geodetic Survey tide gage at Sitka, on Sitka Sound, 137 miles southeast of the entrance of Lituya Bay. The waves began at 11: 25 p.m., July 9, with a height of about 0.1 foot, and continued for many hours. The maximum wave height of about 0.3 foot occurred at about 2:40 a.m., July 10 (H. A. Karo, written communication, May 20, 1959). The first wave arrived at Sitka approximately 65 minutes after the giant wave washed over the entrance of Lituya Bay into the sea; the indicated average speed of about 126 miles per hour, assuming a nearly straight line route of travel through Salisbury Sound and the narrow waterways east of Kruzof Island, is comparable to the observed velocities of tsunamis. It is possible that the waves at Sitka were generated by fault displacement or some effect of the resulting earthquake at a point of origin other than Lituya Bay. Such waves were observed within a few minutes after the earthquake at Dixon Harbor 45 miles southeast of Lituya Bay (William Brammer, oral communication, July 10, 1958) and at Yakutat 99 miles northwest (Brazee and Jordan, 1958, p. 38), as well as on inland waters in Glacier Bay 60 miles to the east (observed by the writer).

Observations of the Writer on July 10

About 1-1/2 hours were spent over Lituya Bay in a small airplane on the morning of July 10, beginning about 12 hours after the wave had passed through the bay. Observations made at this time on the more ephemeral phenomena associated with the earthquake and wave are described separately here because they bear particularly on the interpretation of the eyewitness accounts and on the nature and sequence of events in Lituya Bay on the day of the wave. The observations were recorded on a map, and by means of notes, still photographs, and movies. Kenneth Loken, pilot of the airplane, had flown over Lituya Bay on July 7 and was able to make an on-the-spot comparison of conditions before and after the July 9 earthquake and wave.

On the morning of July 10 Gilbert and Crillon Inlets and the upper part of the main trunk of Lituya Bay for a distance of 2-1/2 miles from the head were covered by an almost solid sheet of floating ice blocks. Many of the blocks were much larger than are normally seen in the bay, with exposed dimensions, as estimated from oblique photographs, of as much as 50 by 100 feet. Nearly all of the larger blocks had flat upper surfaces and were heavily debris laden, and many had scattered, loose, large rounded boulders on their exposed surfaces. Only scattered small pieces of ice, in normal abundance, were floating in the outer part of the bay beyond Cenotaph Island. Only on the northeast shore of Gilbert and Crillon Inlets and on the large delta at the southeast end of Crillon Inlet was any great amount of ice left stranded on the beach above the high-tide line. The absence of stranded ice blocks on the spur southwest of Gilbert Inlet is especially significant as an indication that the glaciers were not involved in the generation of the initial splash or surge of water at the head of the bay.

The front of Lituya Glacier on July 10 was a nearly straight, vertical wall almost normal to the trend of the valley. Comparison of oblique photographs taken by the writer on July 10 and by Edward Berdusco on July 7 indicate that during the earthquake and wave as much as 1,300 feet of ice had been sheared off of the glacier front, but that the southwest margin had changed very little (fig. 16). The delta on the northeast side of Gilbert Inlet had completely disappeared, and the delta on the southwest side was much smaller. It is possible that ice projected beyond the subaerial part of the glacier front, beneath the inner parts of these deltas and that these projections are the source of the large debris-laden blocks of ice floating in the bay on July 10. The glacier surface for several hundred feet from the front was severely crevassed, probably more so than normal; beyond this terminal zone, however, the glacier as far up as the partly subglacial lake near the sharp bend in Lituya Glacier (pl. 2) showed no evidence of any unusual movement. The level of the lake, according to Loken, may have lowered as much as 100 feet since he had seen it 2 days earlier.

Figure 16. Detailed map of head of Lituya Bay, showing slides, changes in the shoreline and glacier fronts, and trimlines resulting from the 1958 earthquake and giant wave.

The front of North Crillon Glacier and the adjoining large delta showed no indications of any significant forward movement of the glacier or of any other disturbance except effects of washing by the component of the wave that had moved southeastward into Crillon Inlet. The front and lower part of Cascade Glacier similarly showed no effects other than of washing by the wave, which had exposed a narrow tongue of nearly clear ice extending to the shoreline.

The most striking change at the head of Lituya Bay, aside from the new trimline, was the fresh scar on the northeast wall of Gilbert Inlet, marking the recent position of a large mass of rock that had plunged down the steep slope into the water (fig. 16; pl. 4A). Loose rock debris on the fresh scar was still moving at some places, and small masses of rock still were falling from the nearly vertical rock cliffs at the head of the scar. The fresh scar is not present on an oblique photograph taken by Edward Berdusco on July 7. This evidence, as well as Ulrich's account, indicates almost certainly that the rockslide was triggered by the earthquake on July 9. The rockslide is described in greater detail on page 65.

Floating logs and other vegetation formed a nearly continuous raft as much as 1,200 feet wide along the outer 3 miles of the north shore of the bay. Small rafts of logs and individual logs were evenly distributed throughout the rest of the bay, beyond the limits of the ice, and over a fan-shaped area of the sea as much as 5 miles from the entrance of the bay.

Water was still dripping from the wave-washed slopes around the shore of the bay as high as the new trimline on the morning of July 10. The volume of water in streams flowing from Fish Lake and other lakes reached by the wave on both the north and south shores was much larger than normal.


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