Notable Earthquake of the Week
Hebgen Lake, Montana M 7.5 Earthquake

It is one of the largest earthquakes ever recorded in the Rocky Mountains. Located just outside the northwestern boundary of Yellow-stone National Park, the Hebgen Lake M 7.5 earthquake occurred at 11:37 pm, August 17, 1959, and registered shaking intensities of X on the Modified Mercalli scale (a relative intensity rating from 1-12 shown in Roman numerals).

The quake caused several landslides and rock falls, including one enormous slide that temporarily blocked the Madison River Canyon, creating a lake nearly 175 feet deep.

Spectacular fault offsets occurred along the north shore of Lake Hebgen with maximum displacements of 21 vertical feet.

Most of the 28 people killed were due to landslides and rock falls within the mountainous areas.


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