On the morning of October 28, 1983, at 7:06 am, a powerful earthquake struck east- central Idaho between the mountain towns of Challis and Mackay.

The powerful Borah Peak earthquake measured M 7.3 and registered shaking intensities of IX-X on the Modified Mercalli scale (a relative intensity rating from I-XII shown in Roman numerals).

Over 22 miles of surface ruptures occurred along the southwestern flank of the Lost River Range, with maximum vertical displacements measuring 8.8 feet. Two deaths were attributed to falling debris and damage totalled over $12 million.

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