The impact of 63.5 million cubic meters of rock hitting the fjord released forces large enough to be recorded globally. The seismic waves that cascaded across the planet were recorded by sensor stations around the world and were equivalent in energy to a magnitude 5.4 earthquake. The splashing of water within the fjord created a 66-second long-period seiche, a standing wave, that reverberated back and forth for 36 hours.
“It could easily become a catastrophic disaster,” says Fathian. It could, because Tracy Arm is a popular tourist destination.
A close call
During the summer, more than 20 boats sail through the Tracy and Endicott Arms every day, including up to six large cruise ships. If the landslide had occurred a few hours later, in the middle of the tourist day, the outcome could have been tragic. But even at 5:26 in the morning, the tsunami was enough to terrify the few people present in the vicinity.
About 55 kilometers away, on Harbor Island, a group of kayakers saw water rush past their tents 20 minutes after the landslide. The rising tide took away some of their equipment and one of the kayaks. Near No Name Bay, observers aboard a motor boat reported a 2 to 2.5 meter crested wave coming along the beach from the direction of Tracy Arm, followed by a 1 meter secondary wave.
Farther away, 85 kilometers from the source, the crew of the small cruise ship anchored at Fords Terror saw a surge of water falling onto a nearby sandbank; He then physically lifted his boat three meters despite the falling tide. The surge, they reported, lasted until 11 a.m., only to leave their small boat stranded on dry land a few minutes later when the water receded.
At the mouth of the fjord, a National Geographic Venture cruise ship carrying about 150 people was anchored in dense fog. The captain noted currents, whitewater, and a significant amount of ice and debris near the edges of the fjord. Because the shallow, uneven seafloor near the mouth of the fjord acted as an obstacle that sapped the wave’s energy, the people aboard the cruise ship emerged from the event unscathed. “We were miraculously lucky that no one was hurt,” says Fathian.
