The Aug. 17, 1959, M7.3 Hebgen Lake earthquake caused ... the cost of spillway construction and related activities at $18.2 million in 2024 dollars. The 1959 Madison Slide changed the landscape ...

According to eyewitnesses, the Madison Slide occurred from just a few seconds to perhaps half a minute after the strongest shaking of the Hebgen Lake earthquake had subsided. Tragically ...