1958 Alaska Tsunami: Lituya Bay’s 1,720-Foot Megatsunami

The 1958 Alaska tsunami was a megatsunami in Lituya Bay, on the southeast Alaska coast, triggered when a magnitude 7.8 earthquake shook roughly 40 million cubic yards of rock loose from a mountainside and into the head of the bay. The water surged 1,720 feet up the opposite slope, stripped four square miles of forest down to bedrock, and killed two people on a fishing boat near the bay’s entrance. It remains the tallest tsunami ever recorded.

What Set the Wave Off

The earthquake struck at 10:16 p.m. local time on July 9, 1958, rupturing about 125 miles of the Fairweather Fault from Palma Bay to Icy Bay.¹ It was felt over more than 650,000 square kilometers, from Seattle to Whitehorse in the Yukon Territory.²

Inside Lituya Bay, the shaking dislodged roughly 40 million cubic yards of rock from the steep northeast wall above Gilbert Inlet, an arm at the head of the bay. The rock mass fell from a maximum altitude of about 3,000 feet into the water below. The impact also sheared off 1,300 feet of ice from the front of Lituya Glacier and wiped out a stream delta in the inlet.³¹

How Tall the Wave Really Was

The famous 1,720-foot figure is a splash height, not the height of a wave rolling through the bay. When the rockslide hit the water in Gilbert Inlet, the displaced water surged up the opposite slope to a maximum altitude of 1,740 feet, and stripped the forest to bare rock up to a line at 1,720 feet.³ Around most of the rest of the bay, that destruction line, or trimline, stood at about 700 feet.⁴

The gravity wave that actually traveled through the main body of the bay was estimated at 100 to 150 feet high, moving at 97 to 130 miles per hour. Survivor Howard Ulrich put it plainly: “The wave did not go up 1,800 feet, the water splashed there.”³

Fewer than five minutes passed between the earthquake and the wave reaching the fishing boats anchored in the outer part of the bay. In total, it denuded about four square miles of shoreline, tearing out trees up to four feet in diameter.¹

The People Caught in the Bay

Three fishing boats were anchored in Lituya Bay that evening, each carrying two people. What happened to each crew is one of the strangest sets of survival stories in maritime history.

Howard and Sonny Ulrich on the Edrie

Howard Ulrich and his seven-year-old son Sonny were aboard the trolling boat Edrie. After about a minute of violent shaking, Ulrich heard what he called a “great roar” from the head of the bay, followed by what looked like “an explosion of water” in Gilbert Inlet.¹ He handed Sonny a life preserver, told the boy to pray, let out all his anchor chain when the anchor stuck fast, and motored into the oncoming wave.

The wave broke on the left side of Cenotaph Island, the island in the middle of the bay, but stayed smooth on the right. Ulrich steered into it. The Edrie climbed the face, the anchor chain snapped and whipped around the pilothouse, and the boat slid down the back of the wave with the engine still running. Ulrich later said he looked over the stern and saw treetops far below the boat. He navigated through a chop full of logs and ice and cleared the bay entrance around 11:00 p.m. Both father and son survived. Howard Ulrich died in 2014.⁵

Bill and Vivian Swanson on the Badger

Bill and Vivian Swanson’s boat, the Badger, was picked up by the wave and carried over La Chaussee Spit, the narrow strip of land at the bay’s entrance, and dropped into the open ocean on the other side. Swanson described the Badger lodged bow-first near the crest of the wave, “as if surfing it backwards,” while he looked down at treetops far below. The boat was wrecked on the outside of the spit, but the Swansons escaped in a skiff and were rescued shortly after midnight.¹

Orville and Mickey Wagner on the Sunmore

Orville and Mickey Wagner, a young couple from Idaho Inlet near Juneau, were aboard the 44-foot troller Sunmore.⁶ The wave swamped and sank their boat near the bay entrance. An oil slick was later spotted on the water, but neither the Wagners nor the Sunmore were ever recovered.¹

Deaths and Damage Beyond the Bay

The megatsunami itself was confined to Lituya Bay, but the earthquake caused damage across a wide stretch of southeast Alaska. At Yakutat, the only permanent settlement in the epicentral region, the quake knocked down bridges, damaged docks and oil lines, and toppled a water tower.² On nearby Khantaak Island, an 800-foot stretch of beach slumped into the sea and killed three people.¹ Underwater landslides severed a submarine cable between Haines and Skagway, and slight damage was reported in Juneau, Sitka, and other towns.

All five confirmed deaths from the earthquake happened in the water: the two Wagners in Lituya Bay and the three people on Khantaak Island.¹

Why This Bay Keeps Producing Giant Waves

Lituya Bay is a narrow, T-shaped fjord about seven miles long. Its steep, glacially carved walls, deep water, and position directly on the active Fairweather Fault make it uniquely prone to landslide-generated waves. The 1958 event was not the first. It was the largest.

USGS geologist Don J. Miller had been studying the bay’s hazards for years before 1958, and by dating vegetation trimlines along the shore he identified at least four earlier giant waves:

1853 or 1854: a wave reaching 395 feet, likely from a slide off the south wall of the bay at Mudslide Creek.³
About 1874: a wave reaching about 80 feet.³
1899: a wave reaching about 200 feet, possibly caused by a slide or fault movement during one of the great earthquakes of that September. A separate account says it destroyed a native village on Cenotaph Island and killed five people.³⁴
1936: a wave reaching 490 feet, generated in Crillon Inlet, with eyewitnesses describing three waves in close succession traveling about 22 miles per hour.³

Even before the USGS documented these, French explorer Jean-François de La Pérouse noticed a distinct trimline in the bay’s forest when his expedition arrived in July 1786. That same month, three of his small boats were caught in a violent tidal bore at the treacherous bay entrance, and 21 men drowned. The expedition erected a monument on the bay’s only island in their memory, and the island has been called Cenotaph Island, from the word for an empty tomb, ever since.⁷

Miller concluded that the bay’s repeated production of giant waves came from its combination of recently glaciated steep slopes, heavily fractured rock, deep water in an active fault zone, heavy rainfall, and frequent freeze-thaw cycles. He wrote that such waves were “likely to occur again.”³ Scientific analysis suggests a giant wave hits the bay roughly once every 25 years.⁴

Why the Record Still Stands

The 1,720-foot runup at Lituya Bay remains the highest tsunami ever recorded. The USGS classifies it as a “tsunamigenic landslide,” distinct from the ocean-wide tsunamis caused by seafloor earthquakes.⁸ The enclosed, steep-walled fjord let the water rise to a height it never could have reached in the open ocean; the same volume of rock falling into deep, open water would not have produced anything close to that runup.

Wave height and death toll are different things. The 2004 Indian Ocean tsunami, generated by a magnitude 9.3 earthquake, produced waves roughly one-tenth the height of the Lituya Bay wave, yet killed about 230,000 people across 17 countries and caused more than $10 billion in damage.⁹ The Lituya Bay wave killed five people because it struck an essentially uninhabited coastline.

Whether It Could Happen Again

Lituya Bay now lies within Glacier Bay National Park and Preserve, which draws more than 700,000 visitors a year, most arriving by water.¹⁰ The geological conditions that produced the 1958 event have not changed. The Alaska Earthquake Center notes that landslide-generated tsunamis are “especially difficult disasters to prepare for” because technology-based warning systems cannot alert people just a few miles from the source in time.¹ The main defense is education: teaching people in coastal communities to recognize the signs of a landslide and get to higher ground immediately.

Southeast Alaska keeps producing these events. On October 17, 2015, about 180 million tons of rock collapsed into Taan Fiord, an arm of Icy Bay roughly 80 miles from Lituya Bay, generating a tsunami with a peak runup of 633 feet, the fourth-highest ever recorded. No one was killed because the area was uninhabited. Scientists attributed the slide to a century of rapid glacial retreat, decades of ground cracking, heavy rainfall, and minor shaking from a distant earthquake.¹¹ Glaciologist Chris Larsen said that as climate change drives further glacial retreat, the ice that buttresses steep mountain slopes disappears, leaving rock faces increasingly prone to collapse.¹²

1
Alaska Earthquake Center. 60 Years Ago: The 1958 Earthquake and Lituya Bay Megatsunami
2
NOAA National Centers for Environmental Information. Significant Earthquake Information
3
USGS. Giant Waves in Lituya Bay, Alaska (Professional Paper 354-C)
4
NASA Earth Observatory. Lituya Bay’s Apocalyptic Wave
5
Alaska’s News Source. Fault Facts: The World’s Largest Tsunami Was in Our Backyard
6
ExploreNorth. Lituya Bay Tsunami
7
Musée La Pérouse. Lituya Bay or Port des Français
8
Geology.com. Biggest Tsunami Ever Recorded
9
UNDRR. The Tallest Tsunami Wave Ever Wasn’t the Deadliest
10
NOAA. Rainier in Lituya Bay
11
National Park Service. The 2015 Taan Fiord Landslide and Tsunami
12
University of Alaska Fairbanks Geophysical Institute. Giant Wave in Icy Bay