Natural Hazards
How do volcanoes erupt?
Can you predict earthquakes?
What is the difference between a tsunami and a tidal wave?
What is a landslide and what causes one?
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.
How many active volcanoes are there on Earth?
There are about 1,350 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 1,350 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 States, volcanoes in the Cascade Range and Alaska...
What is the relationship between volcanism and the geysers and hot springs in Yellowstone?
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 temperature of boiling at the surface. If it rises...