Frequently Asked Questions
Natural Hazards
The USGS monitors and conducts research on a wide range of natural hazards to help decision-makers prepare for and respond to hazard events that threaten life and property.
Yellowstone Volcano is monitored for signs of volcanic activity. The Yellowstone Volcano Observatory (YVO), is a partnership between the U.S. Geological Survey (USGS), Yellowstone National Park, the University of Utah, the University of Wyoming, UNAVCO, the Montana Bureau of Mines and Geology, the Idaho Geological Survey, and the Wyoming State...
Since the most recent giant (caldera-forming) eruption 631,000 years ago, approximately 80 relatively nonexplosive eruptions have occurred. Of these eruptions, at least 27 were rhyolite lava flows in the caldera, 13 were rhyolite lava flows outside the caldera, and 40 were basalt vents outside the caldera. The most recent volcanic eruption at...
Yellowstone is underlain by two magma bodies. The shallower one is composed of rhyolite (a high-silica rock type) and stretches from 5 km to about 17 km (3 to 10 mi) beneath the surface and is about 90 km (55 mi) long and about 40 km (25 mi) wide. The chamber is mostly solid, with only about 5-15% melt. The deeper reservoir is composed of basalt (...
Yellowstone is a plateau high in the Rocky Mountains, and is snowbound for over six months per year. The mean annual temperature is 2.2°C (36°F), barely above the freezing point of water. However, Yellowstone is also an active geothermal area with hot springs emerging at ~92°C (~198°F) (the boiling point of water at Yellowstone's mean altitude)...
Actually, the source of the hotspot is more or less stationary at depth within the Earth, and the North America plate moves southwest across it. The average rate of movement of the plate in the Yellowstone area for the last 16.5 million years has been about 4.6 centimeters annually. However, if shorter time intervals are analyzed, the plate can be...
The science of forecasting a volcanic eruption has significantly advanced over the past 25 years. Most scientists think that the buildup preceding a catastrophic eruption would be detectable for weeks and perhaps months to years. Precursors to volcanic eruptions include strong earthquake swarms and rapid ground deformation and typically take place...
The diagram below shows that the three largest Yellowstone eruptions emitted much more material than the eruptions of Mount St. Helens (1980), Mount Pinatubo in the Philippines (1991), Krakatau in Indonesia (1883, incorrectly known as Krakatoa), and Tambora in Indonesia (1815).
The largest eruption in the last two million years was about 74,000...
If another catastrophic, caldera-forming Yellowstone eruption were to occur, it would probably alter global weather patterns and have enormous impacts on human activity (especially agricultural production) for many years. At this time, however, scientists do not have the ability to predict specific consequences or durations of possible global...
In some cases, limited scientific drilling for research can help us understand magmatic and hydrothermal (hot water) systems; however, drilling to mitigate a volcanic threat is a much different subject with unknown consequences, high costs, and severe environmental impacts. In addition to the enormous expense and technological difficulties in...
Geothermal energy (heat energy from the Earth's interior), is used to generate electricity in a variety of places throughout the world. Although Yellowstone and its surroundings are a significant geothermal resource, the Park itself is off limits to development. Geothermal developments often cause a decrease in the flow of nearby hot springs and...
An advisory is a general statement about the potential of landslide activity in a given region relative to developing rainfall predictions. An advisory may include general statements about rainfall conditions that can lead to debris-flow activity, and list precautions to be taken in the event of heavy rainfall.
A watch means that landslide-...
An average of 25-50 people are killed by landslides each year in the United States. The worldwide death toll per year due to landslides is in the thousands. Most landslide fatalities are from rock falls, debris-flows, or volcanic debris flows (called lahars).
Twenty three people were killed, at least 167 injured, and more than 400 homes were...