The 1959 Hebgen Lake earthquake (also known as the 1959 Yellowstone earthquake ) occurred on August 17 at 11:37 pm (MST) in southwestern Montana, United States. The earthquake measured 7.2 on the Moment magnitude scale, caused a huge landslide, resulted in over 28 fatalities and left US$11 million (equivalent to $96.48 million in 2019) in damage. The slide blocked the flow of the Madison River, resulting in the creation of Quake Lake. Significant effects of the earthquake were also felt in nearby Idaho