Natural Hazards

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 years ago at Toba Volcano on the island of Sumatra...

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 days to weeks before an actual eruption...

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 (1.8 inches) per year. However, if shorter time intervals are analyzed, the plate can be inferred to have moved about 6.1...

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) and steam vents reported as high as 135°C (275°F)...

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 drilling through hot, mushy rock, drilling is unlikely...

Geothermal energy (heat energy from the Earth's interior) is used to generate electricity in a variety of places throughout the world. Although Yellowstone National Park 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 other geothermal features (like geysers...

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 impacts from such large eruptions. The 1991 eruption of...

USGS earthquake information mechanisms are all triggered by the same system, so they all receive the information at the same time. The time it takes for the system to receive the information primarily depends on the size and location of the earthquake: An earthquake in California is processed and posted to the system in 2.5 minutes (on average). This is because our seismic network is very...

The USGS Earthquake Hazards Program has helicorders (seismogram displays) available for several areas in the United States and the World. Our research partner IRIS (Incorporated Research Institutions for Seismology) has two applications, the Station Monitor and the Global Seismogram Viewer , for viewing seismograms. IRIS also supplies software that allows users to collect and view seismic data...

Ten kilometers is a "fixed depth". Sometimes data are too poor to compute a reliable depth for an earthquake. In such cases, the depth is assigned to be 10 km. Why that number? In many areas around the world, reliable depths tend to average 10 km or close to it. For example, if we made a histogram of the reliable depths in such an area, we'd expect to see a peak around 10 km. So if we don't know...

Magnitude estimates for a given earthquake can vary between reporting agencies due to differences in methodology, data availability, and inherent uncertainties in seismic data. Individual agencies use magnitude estimation procedures designed to meet the agency's specific needs and monitoring capabilities. Even for well-recorded events, differences in magnitude of 0.2 or 0.3 units are common and...

The USGS often updates an earthquake's magnitude in the hours and sometimes days following the event. Updates occur as more data become available for analysis and more time-intensive analysis is performed. Additional updates are possible as part of the standard procedure of assembling a final earthquake catalog. There are physical and operational constraints on how quickly seismic data are...