Yellowstone Caldera facts for kids
Quick facts for kids Yellowstone Caldera |
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The northeastern part of the Yellowstone Caldera, with the Yellowstone River flowing through Hayden Valley and the caldera rim in the distance
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| Highest point | |
| Elevation | 9,203 ft (2,805 m) |
| Geography | |
| Location | Yellowstone National Park, Wyoming, United States |
| Parent range | Rocky Mountains |
| Topo map | USGS Yellowstone National Park |
| Geology | |
| Age of rock | 2,150,000–70,000 years |
| Volcanic field | Yellowstone Plateau Volcanic Field |
| Last eruption | 70,000 years ago |
| Climbing | |
| Easiest route | Hike/auto/bus |
The Yellowstone Caldera is a huge volcanic area. It covers parts of Wyoming, Idaho, and Montana. Most of it is inside Yellowstone National Park. This area is powered by a "hotspot" deep within the Earth. Think of it like a giant, hot plume of rock rising from below.
Over millions of years, this hotspot caused several massive eruptions. These eruptions created huge bowl-shaped depressions called calderas. The Yellowstone area has four of these overlapping calderas. It also has many lava domes and crater lakes.
The first big eruption happened about 2.15 million years ago. The most recent "supereruption" was about 630,000 years ago. This event formed the caldera we see today. The last time lava flowed was about 70,000 years ago.
Scientists at the Yellowstone Volcano Observatory watch the area closely. They say there is no sign of a big eruption happening soon. They know there's a lot of melted rock (magma) underground. But it's not ready to erupt.
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How Yellowstone's Volcano Formed
Yellowstone sits at the end of the Snake River Plain. This area has a long history of volcanic activity. Millions of years ago, huge volcanoes formed the Absaroka Range. Mountains like Mount Washburn are what's left of them.
But Yellowstone's current volcanism is different. It's caused by a "hotspot." This hotspot is a super-hot column of rock. It rises from deep inside the Earth. As the North American Plate slowly moves over this hotspot, new volcanic areas form. This creates a trail of ancient volcanoes. You can see this trail stretching across the Snake River Plain.
Scientists have different ideas about what causes this hotspot. One idea is that it's a giant plume of hot rock. This plume comes from very deep within the Earth. It's like a slow-motion lava lamp. This plume melts rock closer to the surface. This melted rock then becomes magma. This magma is what feeds Yellowstone's volcanoes.
Exploring Yellowstone's Calderas
A caldera is a large, bowl-shaped hollow. It forms when a volcano erupts and its magma chamber empties. The ground above then collapses. Yellowstone has several of these giant calderas. They are stacked on top of each other.
The first major caldera is called the Island Park Caldera. It formed about 2.08 million years ago. Much of it is now hidden under newer rock.
The second caldera is the Henry's Fork Caldera. It is about 19 km (12 mi) wide. It formed after another big eruption.
The caldera we see today is the most recent one. It formed about 630,000 years ago. Scientists believe it's actually two calderas that overlap. They are centered around areas called Mallard Lake and Sour Creek. The edges of this caldera can be seen in places like Purple Mountain.
Even a part of Yellowstone Lake is a caldera! The West Thumb Basin is a smaller caldera. It formed from a later eruption.
Yellowstone's Eruption History
Yellowstone has had three main periods of volcanic activity. These happened between 2.15 million and 70,000 years ago. Each period lasted about 750,000 years. Each cycle included a huge eruption that caused a caldera to collapse. Smaller lava flows and ash eruptions happened before and after these big events.
First Major Eruption Cycle
The first cycle began about 2.15 million years ago. It lasted for about 200,000 years. The biggest event was the Huckleberry Ridge Tuff eruption. This happened about 2.08 million years ago. It created the Island Park Caldera.
This eruption was incredibly powerful. It sent huge amounts of ash high into the air. This ash fell across much of North America. Some ash even reached the Pacific Ocean. After this massive eruption, some smaller lava flows occurred.
Second Major Eruption Cycle
After a quiet period of about 500,000 years, a new volcanic system formed. This led to the second major eruption cycle.
The main event was the Mesa Falls Tuff eruption. This happened about 1.3 million years ago. It formed the Henry's Fork Caldera. This eruption also spread ash far and wide. Ash from this event reached places like Nebraska and Colorado.
After the caldera formed, several smaller lava domes erupted. These domes are now part of the landscape.
Third Major Eruption Cycle
The third cycle began with various lava flows. These flows happened along the edges of what would become the newest caldera.
The most recent "supereruption" was the Lava Creek Tuff eruption. This occurred about 626,000 years ago. It created the large Yellowstone Caldera we see today. This eruption released about 1,000 km3 (240 cu mi) of ash and rock. This ash covered an area of over 3,000,000 km2 (1,200,000 sq mi). It reached as far as the Gulf of Mexico.
Post-Caldera Lava Flows
After the last supereruption, lava continued to flow. These flows formed many of the features inside the caldera. The most recent lava flow happened about 70,000 years ago.
Smaller explosive eruptions also occurred. One such event created the West Thumb of Yellowstone Lake 174,000 years ago. Another explosion 13,800 years ago formed a 5 km (3.1 mi) wide crater at Mary Bay. Today, Yellowstone's volcanic activity shows up as hot springs and geysers. The ground also swells, showing magma is still moving below.
What are the Hazards at Yellowstone?
Earthquakes in Yellowstone
Yellowstone experiences many earthquakes every year. Between 1,000 and 2,000 earthquakes happen annually. Most of these are small, usually magnitude 3 or less.
Sometimes, many earthquakes happen close together. This is called an earthquake swarm. In 1985, over 3,000 earthquakes occurred over several months. Scientists believe these swarms are caused by faults slipping. They are not usually caused by magma moving.
In December 2008, a swarm of over 500 earthquakes happened. Another large swarm occurred in January 2010. The biggest earthquake recorded since 1980 was a magnitude 4.8 in March 2014. These events are normal for the Yellowstone area.
Volcano Activity
The last major eruption of the Yellowstone Caldera was 640,000 years ago. It sent a huge amount of ash and rock into the air. This was Yellowstone's third and most recent caldera-forming eruption.
Geologists carefully watch the ground elevation at Yellowstone. The ground has been rising in some areas. This can show changes in the pressure of the magma chamber below.
Between 2004 and 2008, the caldera floor rose significantly. This was more than had been seen since measurements began in 1923. However, this uplift slowed down after 2010. Scientists at the Yellowstone Volcano Observatory say there is no sign of a supereruption happening soon. They believe these events are not regular or predictable.
In 2013, scientists found that the magma chamber is much larger than thought. It is about 80 km (50 mi) long and 20 km (12 mi) wide. However, only a small part of it is molten rock. This amount is too low for another supereruption.
In 2017, research showed that magma surged into the chamber before the last supereruption. This suggests that the magma reservoir could reach eruptive capacity quickly. But scientists continue to monitor the area closely.
Hydrothermal Explosions
Yellowstone's geothermal activity is due to the magma chamber below. This magma contains dissolved gases under great pressure. If this pressure drops, the gases can expand. This can cause an explosive eruption.
Studies show that a greater hazard comes from hydrothermal activity. This happens independently of volcanic activity. Over 20 large craters have formed in the last 14,000 years. These include Mary Bay and Turbid Lake.
For example, a 2003 report suggested an earthquake may have caused huge waves in Yellowstone Lake. These waves could have opened a sealed geothermal system. This led to the hydrothermal explosion that formed Mary Bay. Even distant earthquakes can affect Yellowstone's geysers and hot springs.
Cultural Significance
IUGS Geological Heritage Site
The International Union of Geological Sciences (IUGS) recognized Yellowstone. They included "The Yellowstone volcanic and hydrothermal system" in their list of 100 geological heritage sites. This was published in October 2022.
They chose Yellowstone for its amazing volcanic eruptions and lava flows. They also recognized its world-class hydrothermal system. An IUGS Geological Heritage Site is a key place. It has geological features important for science.
See also
In Spanish: Caldera de Yellowstone para niños
 | Audre Lorde |
 | John Berry Meachum |
 | Ferdinand Lee Barnett |
