Editing Yellowstone Caldera (section)

===Hydrothermal explosions===
{{Further|Hydrothermal explosion}}
[[Image:HotspotsSRP update2013.JPG|thumb|upright=1.4|Path of the Yellowstone hotspot over the past 16 million years]]

The volcanic eruptions, as well as the continuing geothermal activity, are a result of a great [[mantle plume|plume]] of magma located below the caldera's surface. The magma in this plume contains gases that are kept dissolved by the immense pressure under which the magma is contained. If the pressure is released to a sufficient degree by some geological shift, then some of the gases bubble out and cause the magma to expand. This can cause a chain reaction. If the expansion results in further relief of pressure, for example, by blowing crust material off the top of the chamber, the result is a very large gas explosion.{{Citation needed|date=September 2021}}

Studies and analysis may indicate that the greater hazard comes from hydrothermal activity which occurs independently of volcanic activity.{{citation needed|date=September 2021}} Over 20 large craters have been produced in the past 14,000 years, resulting in such features as Mary Bay, [[Turbid Lake]], and Indian Pond, which was created in an eruption about 1300 BC.{{citation needed|date=September 2021}}

In a 2003 report, USGS researchers proposed that an earthquake may have displaced more than {{convert|77|Mcuft|m3 gal|abbr=}} of water in Yellowstone Lake, creating colossal waves that unsealed a capped geothermal system and led to the hydrothermal explosion that formed Mary Bay.<ref>{{cite web| title = Frequently asked questions about recent findings at Yellowstone Lake| work = Yellowstone Volcano Observatory| publisher = United States Geological Survey| date = September 11, 2008| url = http://volcanoes.usgs.gov/yvo/publications/2003/LakeQA.php| access-date = December 31, 2008}}</ref><ref>{{cite news| title = Tsunami linked to Yellowstone crater| newspaper = [[USA Today]]| date = January 14, 2008| url = https://www.usatoday.com/tech/science/2008-01-14-tsunami-yellowstone_N.htm| access-date = December 31, 2008}}</ref>

Further research shows that very distant earthquakes reach and have effects upon the activities at Yellowstone, such as the 1992 7.3 magnitude [[1992 Landers earthquake|Landers earthquake]] in [[California]]'s [[Mojave Desert]] that triggered a swarm of quakes from more than {{convert|800|mi|km}} away, and the 2002 7.9 magnitude [[2002 Denali earthquake|Denali fault earthquake]] {{convert|2000|mi|km}} away in [[Alaska]] that altered the activity of many geysers and hot springs for several months afterward.<ref>{{cite news| title = Quake in Alaska Changed Yellowstone Geysers| publisher = [[University of Utah]]| date = May 27, 2004| url = http://unews.utah.edu/p/?r=030306-10| access-date = December 31, 2008}}</ref>

In 2016, the USGS announced plans to map the subterranean systems responsible for feeding the area's hydrothermal activity. According to the researchers, these maps could help predict when another eruption occurs.<ref>{{cite web|title=We're About to Find Out What's Rumbling Below The Yellowstone Supervolcano|url=http://www.sciencealert.com/we-re-about-to-find-out-what-s-rumbling-below-the-yellowstone-supervolcano|website=Science Alert|date=November 16, 2016 |access-date=May 22, 2017}}</ref>