For 10 points, identify these geological events in which bodies like Mount St. Helens eject molten rock through the Earth's surface.
In the 1970s, analysis of unique SOFAR spikes suggested a large number of previously undetected instances of this kind of phenomenon. Products of these events can be analyzed by using TAS diagrams or examining hydration rinds, and marine instances are associated with hyaloclastite. Materials often become tuffaceous as a result of these phenomena, the subject of the Dense (*) Rock Equivalent metric. Mofettes result from periodic degassing following these phenomena, while maar formation characterizes phreatic ones that interact with the water table. Mass asphyxiation results from a distinct event known as their "limnic" type, and they can trigger destructive lahars as a result of tephra-rich pyroclastic flow. Pumice, basalt, and obsidian from from the major material associated with these events; that material is often in the form of 'A'a or Pahoehoe. For 10 points, identify these geological events in which bodies like Mount St. Helens eject molten rock through the Earth's surface.
In the 1970s, analysis of unique SOFAR spikes suggested a large number of previously undetected instances of this kind of phenomenon.
Volcanic Eruptions [accept reasonable equivalents including anything mentioning Volcanoes, etc.]