Surf's Up

A little slice of history for you kids, on a slowish day / week of stories...

The tallest wave ever recorded — splashing nearly 500 feet taller than the Empire State Building — exploded down Lituya Bay in the Gulf of Alaska on this date in 1958, and proves that Sarah Palin is not the only disaster to hit the state from seamingly out of the blue.

Lituya Bay is a T-shaped fjord on the coast of the Alaskan Panhandle, west of Glacier Bay and about 120 miles west-northwest of Juneau. It measures 7 miles long by 2 miles at its widest point and has a narrow mouth (roughly 1,600 feet wide) that makes navigation difficult during high tides. Once inside, however, vessels (mostly fishing boats) find a snug anchorage among the coves lining the shore. Water from three glaciers empties into Lituya Bay, which is over 700 feet deep in places.

This topography was a major ingredient in the formation of the tsunami. (Or, more informally, megatsunami, a word used to describe a wave in excess of 328 feet). The trigger, however, was a massive landslide at the head of Lituya Bay, caused by an earthquake that may have been as powerful as the one that helped destroy San Francisco in 1906. About 40 million cubic yards of rock — some of it falling from a height of 3,000 feet — plunged down the face of Lituya Glacier into Gilbert Inlet at the northern end of the bay.

Sudden water displacement created a wave that shot seaward from the land, and that was certainly a factor in what followed. But similar occurrences in Norway, where fjords are plentiful, never produced a wave remotely close to the size of this one.

The wave generated at Lituya Bay that night measured an astounding 1,720 feet tall. How a wave could have reached such a height remains speculative, but scientists studying the aftermath observed that a subglacial lake behind Lituya Glacier had dropped 100 feet in depth. The likeliest explanation for that is the missing water broke through fissures caused by the quake and reached the fjord, adding to the pressure. But even with this factor accounted for, geologists don’t believe that alone would have been enough to create such an enormous wave. A precise explanation has never been offered.

Incredibly, several eyewitnesses on the bay at the time the tsunami struck, lived to tell the tale. (Two did not. They were killed when the wave sank their fishing boat near the mouth of the bay.) The wave’s force leveled all the trees and stripped the vegetation along both shorelines — up to 1,720 feet above sea level near the glacier at the head of the fjord (middle left in the photo). At the mouth , La Chaussee Spit and Harbor Point were completely denuded by the raging tsunami. Nevertheless, the wave quickly ran out of steam as it entered the Gulf of Alaska and soon dissipated, causing no further problems.

The 1958 wave was by far the largest to devastate Lituya Bay, but it was only the latest to be documented there by the U.S. Geological Survey. Previous monster waves struck the fjord in 1853, 1874, 1899 and 1936. If Palin gives her farewell address there later this month, the epic crash of her carrer may churn up waves...