World’s Tallest Tsunami Hit An Alaskan Bay In 1958 And It Was Not The First Of Its Kind
July 9, 1958 a magnitude 7.7-8.3 earthquake triggered a landslide in a remote bay along the southern coast of Alaska. The Lituya Bay was a popular meeting spot for local fishermen and that day three fishing boats were anchoring there. The seven miles long and two miles narrow bay was protected from waves by two promontories, separating it from the open sea. Seen from above, the bay resembles a T-shape, this particular shape is caused by the Fairweather Fault, crossing the end of the bay from southwest to northeast.
The quake was generated along this fault. During the rockfall, 40 million cubic yards of material plunged from the mountain slope down into the sea, a jump of approximately 3,000 feet. Part of the rockfall hit the Lituya Glacier. Ice and water from the glacier contributed to the tsunami generated by the sudden impact of the rockfall on the sea. It is also quite possible that movements of the ground pushed the wave even further up the slopes along the inlet. Trees washed away be the wave along the slopes of the Gilbert-Inlet, on the opposite shore where the rockfall hit the sea, suggests a maximum wave height of 1,720 feet! Along the Lituya bay, the wave was still 100 feet high. In the bay the wave was 50 to 75 feet high, as Howard Ulrich, one of the surviving fishermen, later estimated. Of the three boats anchored that day in the bay, one was damaged and later sunk, but all passengers could be saved. Unfortunately, another boat and two persons vanished without a trace, carried by the tsunami out into the open sea.
The quake was powerful enough to generate a series of landslides, both in the sea as on land, in a distance of 155 miles from the quake epicenter. Smaller tsunami, with a maximal wave height of 20 feet, occurred on that day in the Yakutat Bay, Disenchantment Bay, Dry Bay, Glacier Bay, Inian Island, Skagway, and Dixon Harbor.
It’s interesting to note that historic documents and even myths suggest that megatsunami are quite common in the Lituya Bay.
Since 1853 at least four or five similar events are documented. Tree-rings records suggest that in 1853 or 1854 a giant wave damaged many trees along the bay.
Photographs of trimlines taken from 1894 to 1929 show that at least one 400 feet high or possibly two waves occurred between 1853 and 1916. In October 1936 a 490 feet high wave swept over the bay. The 1958 tsunami was, however, the largest wave yet, destroying every evidence of previous events. French explorer Jean-François de La Pérouse (1741-1788), who is credited with the discovery of the Bay in 1786, noted that the shores of the bay ‘had been cut cleanly like with a razor blade’, suggesting that a tsunami occurred also shortly before his arrival. Local legends suggest even older events, predating modern explorers and scientists. A tale told by the native Tlingit Indians locates a mysterious cave deep below Lituya Bay. This cave is inhabited by the evil spirit ‘qa-htu-‘a’, similar in appearance to a great toad or frog. It will sleep for centuries there, only if someone dares to disturb the tranquillity of the bay (and presumably the slumbering spirit), it will violently shake the land and the sea. With gigantic waves it will catch the intruder, transforming it into a bear, common animals in the Alaskan wilderness. A unique artifact, in the form of a pipe made of wood and brass, by a Tlingit artist depicts this moment. The waves across the bay are symbolized by small, triangular pieces of brass, inserted into a wooden framework, so they can even move and simulate the movement of the water. The cursed bears will be on the watch for other intruders, hiding in the Fairweather Mountains, so that qa-htu-‘a will be ready to send another deadly tsunami at any time.