Quake Lake

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Quake Lake

• The Story of the 1959 Hebgen Lake Earthquake

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Hebgen Lake, Montana
In 1959, a 7.5 magnitude earthquake struck the
area known as Hebgen Lake, Montana, just west of
Yellowstone National Park.
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Hebgen Lake, Montana
Epicenter
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Fault Scarp - A fault scarp is a feature on the
Earths surface that looks like a step or scar.
It is created by slip along a fault during an
earthquake.
Several new fault scarps formed during the Hebgen
Lake earthquake. The largest was the Red Canyon
scarp located north of Hebgen Lake. It is 14
miles long with a maximum height of 21 feet.
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Dead End
Evacuating after the Hebgen Quake was not easy! A
splay of the Red Canyon fault scarp lifted a
10-foot wall across the road, blocking escape in
that direction.
Road Bed
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Hebgen Fault Scarp
The north shore of Hebgen Lake was submerged when
the rock on which it rests dropped down adjacent
to the new Hebgen fault scarp. The main residence
at Hilgard Lodge dropped off its foundation into
the lake and floated to this location.
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Tilted Lake
The sudden down-dropping movement along the new
Hebgen fault scarp tilted the lakebed, causing
the water in the lake to shift towards the north
shore (left). The shift created a sloshing motion
in the lake called a seiche wave. Notice the
newly-formed Hebgen fault scarp to the far left
and the small landslide (upper third of photo)
that dropped part of Highway 287 into Hebgen
Lake.
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Seiche Waves
Driftwood was thrown up onto the road by the
seiche waves (oscillatory waves) in Hebgen Lake.
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High and Dry
Northward tilting of Hebgen Lake submerged the
north shore and left these boat docks high and
dry along the south shore. This down-dropping of
the lakebed caused the waves that overtopped the
dam 4 times and continued oscillating 11 1/2
hours.
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These seiche waves were caused by the sudden
down-dropping and tilting of the lake bottom
during the earthquake According to eye-witnesses,
seiche waves overtopped the dam 4 times and
continued oscillating in the lake for 11 1/2
hours after the actual quake.
The Hebgen Lake Dam is a man-made, earth-fill,
concrete core dam that was built on the Madison
River in 1914. The dam survived the intense
vibrations of the earthquake as well as the
repeated seiche waves which overflowed from
Hebgen Lake.
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Seiche Wave
George Hungerford, dam caretaker, observed 3-4
foot surges of water overtopping the dam. Each
surge of water flowed an estimated 10 minutes
before withdrawing. The earthquake also caused
the earth-fill to crumble away, leaving the
concrete core wall exposed. Its sod covering
remained in place. The earthquake and seiche wave
also created several cracks in the dam. The
largest of the 16 cracks in the wall was 3 1/2
inches wide. Despite all of this the dam held.
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U.S. Forest Service smoke jumpers were first into
the area between Hebgen Dam and the landslide to
check on campers, administer first aid, and relay
rescue needs to the outside world.
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Landslide
The earthquake also triggered a large landslide
downstream from Hebgen Lake along the Madison
River Canyon. The Madison Canyon landslide, six
miles below Hebgen Dam, was the most devastating
result of this earthquake. Nearly half of a
mountain fell to the canyon bottom,
Credit MHS Photograph Archives, Helena
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The Madison Canyon landslide, six miles below
Hebgen Dam, was the most devastating result of
this earthquake. Nearly half of a mountain fell
to the canyon bottom, covered part of Rock Creek
campground, blocked State Highway 287, and dammed
the Madison River, causing Earthquake Lake to
form. Twenty six people were killed by this
landslide, but only seven bodies were found. The
remaining 19 are presumed buried under the
landslide. This photo was taken the day after the
earthquake.
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Before and After
These photos by the USGS show the Madison River
Canyon near Rock Creek campground before the
slide (left), and after (right). When the south
mountainside collapsed, it formed a natural dam
that blocked the flow of the Madison River,
forming Earthquake Lake.
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Trapped
The dropping of the lake-bed and four small
landslides destroyed portions of Highway 287
above the man-made dam. Thus, for people in the
Madison Canyon below the man-made dam but above
the landslide when the quake hit, all exit routes
were blocked.
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Rescue and Recovery Efforts
Because of the blocked roads, rescue crews had to
hike into the canyon. Divers were brought in to
look for bodies in the newly formed quake lake
while other search and rescue volunteers combed
the canyon, looking for potential survivors.
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Restoring the River
Once Hwy 287 was cleared and rebuilt, bulldozers
were brought in to create a spillway though the
landslide was blocking the flow of the Madison
River through Madison Canyon. However, most of
the landslide was left in place, and Quake Lake
can still be visited today.
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Damage in Yellowstone National Park
The earthquake caused rockfalls and landslides
throughout the northwest section of Yellowstone
National Park. This rockfall blocked the road at
Golden Gate Canyon. A later slide just missed
five park workers. New geysers erupted, and
massive slumping caused large cracks in the
ground from which steam emitted. Many hot springs
became muddy.
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Other Damage
Two people died at Cliff Lake Campground, 15
miles southwest of the Madison Canyon landslide,
when a large boulder bounced over the picnic
table and landed on their tent. Their three sons,
sleeping a few feet away, were not injured.
Picnic Table
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Hebgen Lake, Montana
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Hebgen Lake, Montana, Earthquake August 1959.
Fault scarp at Cabin Creek. 1959.
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Hebgen Lake, Montana, Earthquake August 1959.
Scarp area at the head of the Kirkwood earthflow,
showing maximum distension of the surface,
toppled trees, soil destroyed, and much subsoil.
View is east from the east edge of the flow.
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The Red Canyon fault scarp cuts through the old
Culligan barn at the Blarneystone Ranch. The
barn was actually part of the servants'
quarters of Blarneystone Ranch. The barn sits
mainly on the down thrown block. The fault scarp
here is 10 to 12 feet high.
A small collapsed shed (green roof) was on the
upthrown block. It was completely destroyed. The
fault scarp ends in the small grove of aspen
which shows just beyond the barn.
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Hebgen Lake, Montana, Earthquake August 1959.
Landslide into Hebgen Lake. August 1959.
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Red Canyon fault scarp as exposed along the south
flank of Kirkwood Ridge near the head of Kirkwood
Creek. The fault scarp here is wholly in
colluvial debris. Part of the slickensides have
been chopped away to show the general texture of
the material. The slickensides dip downslope,
reflecting direction of the movement of the
colluvium. August 1959.