![]() ![]() Montana sits atop the Intermountain Seismic Belt (ISB), which is a 60 mile wide belt of earthquake-prone geology following the Rocky Mountains from Flathead Lake down all the way into Nevada. The creepy treetops are clues to the lake’s strange and abrupt formation, which began on the night of 17th August, 1959.When we talk about Montana’s earth-shattering history, we mean that very literally. With the tree trunks rising from its waters, Earthquake Lake is eerie-looking. Forest Service placed a plaque on one of the boulders that fell during the quake to honour the people who were killed during the tragic event. One year later, fifty people, including Police Officers and the Red Cross held a memorial service in Madison Canyon for the campers buried underneath the quake-induced landslide. Hebgen Lake rose eight feet, and roads and highways running along the shores of the lake collapsed into the water. The quake caused new geysers and cracks to sprout up in nearby Yellowstone National Park, knocked out telephone communications between Bozeman and Yellowstone, and caused a pendulum clock in Butte to stop at 12.42 a.m. The effects of the earthquake were widespread. Tourists camping in surrounding areas were caught off guard by the quake and landslide, inundating trailers and tents, causing more fatalities. In Madison Canyon, the landslide swept away families, many of whom perished. The landslides caused by the earthquake carried 80 million tonnes of rock, mud and debris down into the valley and created hurricane-force winds strong enough to toss cars and uproot trees. Several aftershocks ranging from 5.8 to 6.3 were reported after the quake. Water pushed by the seiches poured over the dam which hadn’t collapsed. During that time, the surrounding landscape dropped as much as 20 feet (6m) and shockwaves caused numerous seiches (standing waves in an enclosed body of water) to surge across Hebgen Lake for 12 hours. ![]() Weather Bureau reported that the 7.5 magnitude quake lasted 30-40 seconds. The effects of the earthquake were felt in Idaho and Wyoming. It also caused the worst landslides in the history of the Northwestern United States since 1927. The 1959 earthquake was the strongest and deadliest earthquake to hit Montana since the 1935-36 Helena earthquakes left 4 people dead. Tragically, the earthquake buried homes and cabins, destroyed roads and buildings, and killed 28 people who were camping on the shores of Hebgen Lake and the Madison River. What remains today is Quake Lake (officially Earthquake Lake) in Montana, USA. Only the tops of the drowned trees remained to show where forest once covered the canyon floor. Within three weeks the lake was five miles long and had reached a maximum of 190 feet deep. Over the following weeks, the water rose nine feet per day as increased streamflow (triggered by the earthquake) poured down the Madison. By dawn the next day, a brand new lake, churning with muddy water and strewn with broken trees, had risen to engulf the campground near the landslide. ![]() The slide created a rock dam across the Madison River, blocking the river’s swift current. At 11.37pm on 17th August 1959, a 7.5 magnitude earthquake shook southwestern Montana and triggered a colossal landslide across Madison Canyon. ![]()
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