The impact of 63.5 million cubic meters of rock hitting the fjord was so large that it was recorded globally. The seismic waves that hit the entire planet were recorded by sensor stations around the world and their energy was equivalent to a magnitude 5.4 earthquake. The slow waters within the fjord set off a 66-second-long seiche, a standing wave that echoed back and forth for 36 hours.
“This could easily turn into a catastrophic disaster,” Fathian says. This may be because Tracy Arm is a highly frequented tourist destination.
a close call
During the summer, more than 20 boats visit the Tracy and Endicott arms each day, including six large cruise ships. Had the landslide occurred a few hours later, in the middle of a tourist day, the outcome could have been tragic. But even at 5:26 in the morning, the tsunami was strong enough to scare the few people present nearby.
On Harbor Island, about 55 kilometers away, a group of kayakers saw water flowing over their tent 20 minutes after the landslide. The rising tide took away some of their belongings and a kayak. Nearby in No Name Bay, observers on a motor ship reported a 2–2.5 meter cresting wave coming along the beach from the direction of Tracy Arm, followed by a second wave of 1 metre.
The crew of a small cruise boat anchored at Fjords Terror, 85 kilometers from the source, observed flooding of water on a nearby sandbar; This physically lifted their ship three meters despite the falling tide. He said the surge continued until 11 a.m., but a few minutes later, when the water receded, his small boat ran aground on dry land.
At the mouth of the fjord, a National Geographic Venture cruise ship carrying about 150 people was anchored in dense fog. The captain observed currents, white water, and large amounts of ice and debris near the edges of the fjord. Because the shallow, shallow seabed near the mouth of the fjord acted as a breakwater that absorbed the wave’s energy, those on the cruise ship came out unharmed. Fethian claims, “It was our good fortune that no one was hurt.”
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