The Yellowstone Caldera was formed by a high-pressure mantle plume that originated from a hot spot deep beneath the Earth’s crust under Yellowstone. The massive mantle plume, stretching 400 miles below the surface of the Earth, is a column of molten rock that is less dense than surrounding material and has forced its way to the surface. The presence of a hotspot beneath Yellowstone led to the formation of a super volcano in the center of the North American plate despite being far from any plate boundaries.  

Scientists employ several methods to study volcanic activity and predict future eruptions or other volcanic activity that may occur. One of these tools is the seismometer. At Yellowstone, more than 150 seisometers form the seismic network over 100,000 mi2.  There is a new technique being used by scientists that utilizes muons, a special form of light that comes from cosmic rays from distant explosions in space after they collide with Earth’s atmosphere. Muons can penetrate through entire mountains and provide a graphic of the structure within unlike any method seen before. Using cosmic rays, scientists, such as the study of Vesuvius and Mount Asama, can obtain and image of the interior of a volcano and use the data collected to predict volcanic activity. Finally, scientists utilize acoustic flow monitors. In the city of Orting near Mt. Rainier, acoustic flow monitors are installed in the valleys around the volcano. Acoustic flow monitors detect ground vibration which are a characteristic of lahars. With this early warning system in place, alarms will activate if a lahar is coming and give people a better chance at reaching higher ground. 
 
Geologists and researchers have found signs leading them to believe that the massive supervolcano Naples is situated on is waking from its slumber. Since the 1970s, Naples and the neighboring region has risen by 10 feet. Naples sits upon Campi Flegrei, a supervolcano only a few miles below the surface. Scientists aren’t certain about the cause, and it could be either a buildup of water and hot gas or magma filling up the chamber of the supervolcano. If it is magma causing the changes to elevation in Naples, the likelihood of an eruption increases. In the marketplace built 2,000 years ago in Naples, ancient pillars reveal ancient bore holes 10 feet above the ground made by marine mollusks that only live underwater. The pillars are now above sea level, leading scientists to believe that at some point in the last 2,000 years Naples was underwater.  
 
An increase in sulfur content in the atmosphere can be a warning sign of an impending volcanic eruption, and sulfur is what is looked for in ice cores for this reason. One of the deadliest gases that is a warning sign of a volcanic eruption is sulfur dioxide. Another of the most common volcanic gases is carbon dioxide. Since CO2 is present almost everywhere, scientists must get close to the volcano to take accurate measurements. Alessandro Aiuppa, a researcher looking at the volcano off the coast of Italy, has found evidence that an increase in CO2 which comes from high pressure areas deep below the volcano always precedes major volcanic activity. Aiuppa compares the effect of the rising gases to a bottle of soda, where the gases rapidly decompress as soon as you open the lid. Like soda, CO2 is dissolved in magma and rises to the top when an eruption is imminent. 
