Researchers Think Melting Glaciers Contributed To The Massive Alaskan Earthquake In 1958
One of the largest earthquakes ever recorded within the United States happened in 1958 in Alaska. The quake was a magnitude 7.8 and triggered a massive rockslide the Southeast Alaskan Lituya Bay, creating a tsunami that reached 1700 feet up the side of a mountain before heading out to sea. Researchers from the University of Alaska Fairbanks Geophysical Institute published a paper recently linking widespread loss of glacier ice with that earthquake.Scientists say ice loss near Glacier Bank National Park has influenced the timing and location of earthquakes with a magnitude of 5.0 greater in the area during the past century. Researchers have known that melting glaciers cause earthquakes in other tectonically stable regions, including in Canada and Scandinavia. This activity was more difficult to detect in Alaska as earthquakes are more common in the southern part of the state.
Alaska is home to some of the largest glaciers in the entire world, with ice thousands of feet thick in some areas covering hundreds of square miles. The massive weight of the ice forces the land beneath it down, and when the glacier melts, the ground can spring back up in a sponge-like manner. This is known as the "elastic effect," causing the earth to spring back up after an ice mass is removed.
Researchers have linked the mantle's expanding movement with large earthquakes across Southeast Alaska, where the glaciers have been melting for over 200 years. So far, more than 1200 cubic miles of ice have been lost. Southern Alaska sits on a boundary between the North American tectonic plate and the Pacific Plate, which grind by each other at about two inches per year which is about twice as fast as the famous San Andreas Fault in California.
The disappearance of ice has caused the land in Southeast Alaska to rise about 1.5 inches per year. According to the researchers, models of earth movement and ice loss since 1770 have found an unmistakable correlation between earthquakes and earth rebound. They found most quakes in the area correlated with stress from long-term earth rebound. Interestingly, the greatest amount of stress from ice loss occurred near the exact epicenter of the 1958 quake in Lituya Bay.