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.

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Screenshot of Volcanoes and Current Activity Alerts
There are about 1,500 potentially active volcanoes worldwide, aside from the continuous belts of volcanoes on the ocean floor at spreading centers like the Mid-Atlantic Ridge. About 500 of those 1,500 volcanoes have erupted in historical time. Many of those are located along the Pacific Rim in what is known as the "Ring of Fire." In the United...
Image: Northeastern Vent of the Kamoamoa Eruption
Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic...
Ash and plume lightning over the Sakurajima volcano, southern Japan eruption in February of 2013
Yes, volcanoes can affect weather and the Earth's climate. Following the 1991 eruption of Mount Pinatubo in the Philippines, cooler than normal temperatures were recorded worldwide and brilliant sunsets and sunrises were attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that drifted...
Ash cloud rising from volcano
There is no definitive evidence that an eruption at one volcano can trigger an eruption at a volcano that’s hundreds of kilometers/miles away or on a different continent.   There are a few historic examples of  simultaneous eruptions from volcanoes (or volcanic vents) located within about 10 kilometers (6 miles) of each other, but it's difficult...
Scientist sampling water at Azure Hot Spring, Yellowstone National Park
Heat and volcanic gases from slowly cooling magma rise and warm the dense salty water that occupies fractured rocks above the Yellowstone magma chamber. That brine, in turn, transfers its heat to overlying fresh groundwater, which is recharged by rainfall and snowmelt from the surface. Water boiling at depth below the surface is hotter than the...