Small Earthquakes in Yellowstone (30 in 48 hours, 4 in last hour)

AP ^ | 12/27/2008

[briarbey b]

Earthquakes
From 1,000 to 3,000 earthquakes typically occur each year within Yellowstone National Park and its immediate surroundings. Although most are too small to be felt, these quakes reflect the active nature of the Yellowstone region, one of the most seismically active areas in the United States. Each year, several quakes of magnitude 3 to 4 are felt by people in the park.

Although some quakes are caused by rising magma and hot-ground-water movement, many emanate from regional faults related to crustal stretching and mountain building. For example, major faults along the Teton, Madison, and Gallatin Ranges pass through the park and likely existed long before the beginning of volcanism there. Movements along many of these faults are capable of producing significant earthquakes. The most notable earthquake in Yellowstone’s recent history occurred in 1959. Centered near Hebgen Lake, just west of the park, it had a magnitude of 7.5. This quake caused $11 million in damage (equivalent to $70 million in 2005 dollars) and killed 28 people, most of them in a landslide that was triggered by the quake.

Geologists conclude that large earthquakes like the Hebgen Lake event are unlikely within the Yellowstone Caldera itself, because subsurface temperatures there are high, weakening the bedrock and making it less able to rupture. However, quakes within the caldera can be as large as magnitude 6.5. A quake of about this size that occurred in 1975 near Norris Geyser Basin was felt throughout the region.

Even distant earthquakes can affect Yellowstone. In November 2002, the magnitude 7.9 Denali Fault earthquake struck central Alaska, 1,900 miles (3,100 km) northwest of Yellowstone. Because this quake’s energy was focused toward the active Yellowstone volcanic and hydrothermal system, it triggered hundreds of small earthquakes there. The region’s hydrothermal system is highly sensitive to quakes and undergoes significant changes in their wake. Earthquakes may have the potential to cause Yellowstone’s hot-water system to destabilize and produce explosive hydrothermal eruptions.

[wolfcreek]

Could be nothing, could be the END or anything in between.

[TriGirl]

I believe there were a few avalanches in Jackson hole, killing a skier in the past few days. Probably related?? Went to college up there, LOVED it.

[Question_Assumptions]

It probably won't take out all of North America (after all, it has erupted several times in the past and North America exists around it) but it would probably mean the end of the United States as we know it. You can find a map of the ash fall zones from previous eruptions here.

[saganite]

You (will) have been a participant in the biggest interdimensional cross rip since the Tunguska blast of 1909!

[saganite]

especially since I own land in Wyoming.

Look on the bright side. If it erupts you’ll own land all over the planet!

[Dick Bachert]

When THIS puppy blows — and it will — it will me HUGE.

Now if we could just get the prevailing winds over Yellowstone to blow from east to west for a few days after it does, it would solve the California and Hollywood “problems” as well. If we could get some of those West Hollywood types to stand outside, face East and suck for a few days, that’d do it.

MEMO TO JIMROB: GO EAST, YOUNG MAN, GO EAST!

[SnarlinCubBear]

If this blows, it’s Obama’s fault.

[EternalVigilance]

Which of course killed folks, and made quite the lake:

Quake Lake (also known as Earthquake Lake) is a lake in southwestern Montana, United States. It was created after a massive earthquake struck on August 17, 1959. Today, Quake Lake is 190 feet (58 m) deep and six miles (10 km) long. US 287 follows the lake and offers glimpses of the effects of the earthquake and landslide and allows access to a visitor center. The lake is mostly within Gallatin National Forest.

The earthquake

Main article: 1959 Yellowstone earthquake

The earthquake measured 7.3 on the Richter scale and caused an 80 million ton landslide which formed a landslide dam on the Madison River. The landslide traveled down the south flank of Sheep Mountain, at an estimated 100 miles per hour (160 km/h), killing 28 people who were camping along the shores of Hebgen Lake and downstream along the Madison River. Upstream the faulting caused by the earthquake forced the waters of Hebgen Lake to shift violently. A seiche, a wave effect of both wind and water, crested over Hebgen Dam, causing cracks and erosion. Besides being the largest known earthquake to have struck the state of Montana in recorded history, it is also the largest earthquake to occur in the Northern Rockies for centuries and is one of the largest earthquakes ever to hit the United States in recorded history.

The earthquake created fault scarps up to 20 feet (6 m) high in the area near Hebgen Lake and the lake bottom itself dropped the same distance. 32,000 acres (130 km²) of the area near Hebgen Lake subsided more than 10 feet (3 m). Several geysers in the northwestern sections in Yellowstone National Park erupted and numerous hot springs became temporarily muddied.

Hebgen Dam and creation of the lake

Hebgen Dam, built in 1914, is a concrete core and rock fill faced structure that sustained severe damage but continued to hold. Repairs were completed on the dam spillway in a few weeks. The landslide, which occurred downstream from the dam, blocked almost all the flow of the Madison River which began to fill in the void upstream from the slide. In less than a month, the waters had created what is now known as Quake Lake. The lack of a reliable water outlet for this new lake forced one of the largest mobilizations of the U.S. Army Corps of Engineers ever commenced in the western U.S. Before the new landslide was breached by the quickly rising waters, a spillway was constructed to ensure erosion and potential failure of the natural dam would be minimized.

Within the immediate vicinity of the earthquake and resultant landslide a few dozen cabins and homes were destroyed. Overall damages to buildings and roads were minor with damage costs placed at 11 million dollars in 1959. Aftershocks up to 6.5 on the Richter scale continued for several months.

[redgolum]

Cool

[navyguy]

LOL! Good point!

[bd476]

Thanks for the ping, Ernest. Even though they're small quakes, that's a lot of earthquake activity there.