For most of its lifetime, though, Yellowstone has engaged in two far more benign forms of eruptive activity: lava flows, and hydrothermal blasts. The former have always been isolated to the area around what is now the national park; the latter – which happens when water gets mixed up with superheated rock or magma/lava, causing an explosive release of heat – also abides by the same rules.
The earthquake that devastated San Francisco in 1906 may still be able to help us better understand future quakes. Over a century later, the marks it left on the coastal and offshore landscape of northern California may offer some clues about what might happen when the fault ruptures again.
Germany's Laacher See Volcano (LSV): Around 12,900 years ago, a cataclysmic eruption, one that coated plenty of Europe in ash, was responsible for creating the crater-like edifice that we can see there today.