The 1959 Hebgen Lake earthquake[2] also known as the 1959 Yellowstone earthquake[2] occurred on August 17[2] at 11:37 pm (MST)[3] in southwestern Montana, United States. The earthquake measured 7.3 – 7.5[4] on the Richter magnitude scale,[5] and caused a huge landslide that caused over 28 fatalities and left $11 million (1959 US$, $88.7 million 2014 US$) in damage. The slide blocked the flow of the Madison River resulting in the creation of Quake Lake. Effects of the earthquake were also felt in Idaho and Wyoming.[6]