Montana 1959, M7.3
Earthquake — On August 17, 1959, Hebgen Lake, Montana was shaken with a
M7.3 quake, the largest earthquake to hit Montana. This earthquake
caused 28 fatalities and about $11 million in damage to highways and
timber. It is characterized by extensive fault scarps, subsidence and
uplift, a massive landslide, and a seiche in Hebgen Lake.
most spectacular and disastrous effect of the earthquake was the huge
avalanche of rock, soil and trees that cascaded from the steep south
wall of the Madison River Canyon. This slide formed a barrier that
blocked the gorge and stopped the flow of the Madison River and, within a
few weeks, created a lake almost 53 meters deep.
houses in the Hebgen Lake area were damaged: houses and cabins shifted
off their foundations, chimneys fell, and pipelines broke. In this photo
we see the main residence of Hilgard Lodge that is almost wholly
submerged in Hebgen Lake. Learn more at: on.doi.gov/Montana1959