Geology - Yellowstone National Park (U.S. National Park Service)
violent volcanic activity has most prevalently shaped Yellowstone's Pierce, , Grand Teton Natural History Association The plates of plate tectonics. The caldera is located in the northwest corner of Wyoming, in which the vast majority of the park is What happened during the last eruption of a super volcano? . These tectonic plates move around which are the basis of plate tectonics. These linear chains of volcanoes ran in parallel lines to each other. ridges, but there are a few located in the middle of plates, like Hawaii and Yellowstone.
The previously-held plume model was used to explain the unique Yellowstone hotspot track - the line of volcanoes in Oregon, Idaho, and Wyoming that dots part of the Midwest. So, what caused the track? Zhou intends to find out. The frequent Geyser eruptions at Yellowstone are of course not volcanic eruptions with magna, but due to super-heated water.
The last Yellowstone super eruption was aboutyears ago, according to experts.
Textbook 2.2: Plate Tectonics 1, Yellowstone
Zhou has no predictions on when or if Yellowstone could erupt again. The use of the X-ray-like images for this study is unique in itself.
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Just as humans can see objects in a room when a light is on, Zhou said seismometers can see structures deep within the earth when an earthquake occurs. The vibrations spread out and create waves when they hit rocks. The waves are detected by seismometers and used in what is known as diffraction tomography. Zhou will continue her study of Yellowstone. In addition, the park receives abundant rainfall and snowfall.
The water from rain and melted snow circulates deeply through rocks broken by numerous earthquakes, and the water is heated from below. In some places, the water is heated all the way to steam, which emerges from holes known as fumaroles. In other places, hot water bubbles to the surface in beautiful springs.
If the bubbling action mixes in enough mud, then paint pots, mud pots or mud volcanoes develop.
Sometimes, cold water on top holds hot water down, with the pressure preventing boiling of the hot water in a pressure-cooker effect. Eventually, a little boiling manages to expel a little of the water above, reducing the pressure, allowing more boiling, and a geyser erupts.
Geysers require heat, water, and a tight, tough plumbing system to hold the hot water and withstand the high pressures.
A sinking, melting ancient tectonic plate may fuel Yellowstone’s supervolcano | Science News
The volcanic rocks of Yellowstone are rich in silica, which is dissolved and re-precipitated by the hot waters to seal cracks in the rocks, helping produce geysers.
Yellowstone also is noted for many waterfalls besides those in the Canyon, for a number of other interesting features, and for abundant wildlife, which we'll visit later in the course. Yellowstone itself is centered on the Yellowstone Caldera, a collapse feature related to three great volcanic eruptions, or periods of eruptions. The caldera, roughly 50 x 30 miles 80 x 50 kmincludes Yellowstone Lake but extends well beyond it. No lake in the nation is both higher and larger than Yellowstone Lake, yet it is only a piece of the caldera.
The eruptions occurred roughly 1. Each of these eruptions moved roughly times more material than did the Mt. Helens eruption of that we will discuss soon; thick deposits erupted from Yellowstone are known from the Badlands region of South Dakota.
Yellowstone has many lessons to teach us. Some year, it would be fun to have a course on the geology of Yellowstone alone, and we certainly could fill a semester. The size of the Yellowstone eruptions is of considerable interest, especially considering the likelihood that they will recur. Here, we wish to use Yellowstone to introduce earthquakes.
Colter brought back fantastic tales of the region, which were largely dismissed because they seemed impossible. Other travelers, and especially Jim Bridger in the s, returned with similar tales, which also were discounted, in part because Bridger was a bit of a tall-tale teller. He is credited with stories of petrified birds sitting on petrified trees singing petrified songs an exaggerated description of Specimen Ridgeof rivers that ran so fast they became hot on the bottom the Firehole River, which actually has hot springs on the bottomof trying to shoot an elk and missing because a mountain of glass was in the way Obsidian Cliff, where rapidly-cooled volcanic rocks have made a glass called obsidian, which was mined, shaped, and traded by the native Americansand more.
To separate fact from fancy, the Washburn expedition from Montana Washburn was surveyor-general of the Montana Territory visited the region inand first developed the idea of a national park.
The government-sponsored Hayden expedition of provided scientific documentation of the wonders of Yellowstone, supported by the artwork of Thomas Moran and photography by W. Jackson, which convinced Congress to found the park in Breaks in recent stream and glacier deposits showed the geologists of the party that faulting had occurred recently, and motion on faults produces earthquakes. Since then, modern monitoring equipment has detected numerous quakes in the area. On August 17,a Richter-magnitude 7.
Many of the geysers were changed, and a new one Seismic Geyser suddenly began to erupt. The ground over the quake at the epicenter—the place above the center of the quake was broken, with one side dropped roughly 6 feet 2 meters relative to the other side, and with a little twisting and turning causing even larger drops in some places.
A large landslide was triggered, burying a campground, damming the Madison River to form Quake Lake, and burying many highways. Some survivors had their clothes literally torn off by the immense blast of wind pushed out of the way by the huge landslide. The Old Faithful Inn was evacuated, and the west entrance to Yellowstone closed. Every one in the place dashed for the door.
Much effort has been devoted to detecting underground nuclear tests by the earthquake waves produced. Mining cave-ins, conventional explosions, and other events can cause earthquakes.
The deepest earthquakes, which are very rare but often among the biggest ones, may have a phase-change or "implosion" origin, which we'll discuss later. However, most earthquakes are produced by elastic rebound. We will see that other motions occur as well, with one group of rocks moving past another. Where rocks are warm and soft, they flow.
Yellowstone Super Volcano
Where cold and hard, they cannot flow. Consider, for example, two large pieces of rock, such as southwestern California and the rest of the state. The southwestern part of the state, from Los Angeles to San Francisco, and the adjacent ocean floor are moving northwest relative to the rest of the state. The break separating the different parts is called the San Andreas Fault.
Both sides are moving westward, but the southwest side has an additional bit of northwesterly movement relative to the northeast side.
Faults may go east-west, or north-south, or any other direction, may be vertical or angled, and the rocks may move vertically or horizontally or in-between across the fault.
The forces that move the rocks are huge and applied over large areas, so that far from the fault the motion is smooth. But at the fault, rough patches can get stuck against each other and become locked for a while. The rocks then bend.
This bending is elastic—it can spring back. The springing back is very rapid, in the same way as for a spring or a rubber band. Displacements of several feet more than a meter or more are possible in much less than a second.
A building sitting on the rocks near the fault can be subjected to very large accelerations, and may fall apart. Storage of energy in rocks causes an earthquake. Alley Such an earthquake will shake rocks beyond a fault. This is achieved through seismic waves—one piece of rock pushes another next to it, which pushes one next to it, and so on.
Two major types of seismic waves are P or push, and S or shear.
The P-wave is the ordinary sound wave. It represents a push-pull in the direction the wave is moving. A P-wave moving to the north will shake a mineral grain north-south-north-south. An S-wave moves slower than the corresponding P-wave. When an S-wave moves to the north, the mineral grains are shaken east-west-east-west or up-down-up-down or some combination. A shear wave is similar to the wave you generate by shaking a rope. A piece of the rope moves up and down or back and forth, but the wave moves along the rope.
A P-wave may start a building shaking in one way, and then the S-wave hits the building and starts shaking it a different way, making the building more likely to break and fall down.
Earthquakes also make surface waves, which move more slowly than shear waves and go along the surface of the Earth like wind-driven waves on the ocean, rather than going through the Earth the way P- and S-waves do. The surface waves can also contribute to breaking buildings.
P and S waves traveling through Earth. Wiggle one piece of liquid to the side, and the moving piece slides freely past the next piece rather than wiggling it. Recall that earlier we claimed that the outer core of the Earth is liquid.