The remarkable M7.9 quake that ruptured 330+ km of land
Scientists recorded a surface rupture measuring more than 330 km long in the earthquake’s wake
An intense and exceptionally shallow earthquake struck interior Alaska during the afternoon hours of Nov. 3, 2002.
No significant damage or fatalities occurred as a result of the epicentre’s remoteness. The rare event allowed scientists to study the physical effects of a large earthquake up close.
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One of the largest onshore earthquakes ever recorded in the United States began just past 1:12 p.m. local time around 150 km south of Fairbanks, Alaska.
The magnitude 7.9 began at a depth of just 4 km beneath the surface, a remarkably shallow depth for such a powerful earthquake. Due to that shallowness, folks as far away as Louisiana reported bodies of water and swimming pools sloshing back and forth.
Strong shaking triggered landslides and rockslides throughout the region, though the epicentre was far enough from populated areas that only pipelines and roadways suffered significant damage.
Much of that infrastructure damage occurred due to the ground movement itself. Large earthquakes on strike-slip faults are notorious for producing very long surface ruptures, or significant cracks that appear in the ground along the fault line itself.
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Strike-slip faults, such as the one running beneath the Alaska Range, feature tectonic plates rubbing against one another. When one plate slips and moves during an earthquake, the ground beneath your feet moves right along with it.
Scientists measured a surface rupture more than 330 km long along the fault line that triggered the Nov. 2002 earthquake in the Denali region. Some areas experienced sideways ground movement of around 9 metres, according to the Alaska Earthquake Center. The entire event reportedly unfolded in just 90 seconds.
Alaska’s highly active geology makes it one of the most earthquake-prone regions in North America.
This event remains one of the strongest onshore earthquakes ever recorded in the United States. Before the 2002 earthquake, the most powerful shaking centred directly on U.S. soil struck between San Francisco and Los Angeles in Jan. 1857.