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My limited understanding is that volcanoes in Hawaii are the exception rather than the rule. The rule is that they happen where plates converge: https://www.br

by glial 6y ago

My limited understanding is that volcanoes in Hawaii are the exception rather than the rule. The rule is that they happen where plates converge: https://www.britannica.com/place/Ring-of-Fire https://www.britannica.com/place/Ring-of-Fire

thaumasiotes 6y ago
Yes, that is also what I was taught. But that suggests the following model to me: 1. Volcanoes are caused by Circumstances X, Y, Z, whatever. 2. Collision of two tectonic plates causes Circumstances X. That is, I want the model of "volcanoes" to account for all volcanoes, not just most volcanoes. If we describe circumstances that are necessary and sufficient to create a volcano, we're done; the fact that the interaction of tectonic plates often creates those circumstances -- and even more often doesn't -- isn't really part of the model at all.
- dredmorbius 6y ago
  "Whatever" turns out to be a reasonably limited set of exceptions to tectonic boundary models. Plate tectonics describes and explains the overwhelming majority of known current volcanos and volcanic regions. Mantle plumes, which themselves drive tectonic activity, much the rest. The overall structure of the Earth, with a thin crust, plastic mantle, and hot core with temperatures resulting from both latent heat of gravitational formation and ongoing radioactive decay itself explains much and is entirely consistent with plate tectonics. The principle further exceptions might be simply thin crust, or penetrations by impactors --- the universe is complex, volcanos result from escape or exposure of interior magma to the surface by some mechanism. Gods hurling thunderbolts or smithing armour for other gods, for example, has scant evidence. I'm unaware of any specific terrestrial volcanoes not explained by tectonic or plume mechanisms. There are minor craters (e.g., Ubehebe crater in Death Valley) resulting from steam rather than magmatic bursts, but still driven by geothermal processes. https://en.wikipedia.org/wiki/Ubehebe_Crater https://en.wikipedia.org/wiki/Ubehebe_Crater Further we've now had evidence of similar mechanisms (or their lack) on other bodies, including the Moon (little tectonic activity, some faulting for other reasons, possibly validating Tethys impact formation hypothesis, possible recent volcanism https://coolinterestingstuff.com/volcanoes-erupted-on-the-moon-recently https://coolinterestingstuff.com/volcanoes-erupted-on-the-mo...), Mars (extinct volcanos, former tectonics), Venus (active volcanism, possible tectonics), Mercury (mixed, some faulting thought due to cooling and contraction), and Io (tidal-force induced volcanism), as well as other moons of Jupiter and Saturn.

by glial 6y ago

thaumasiotes 6y ago

Yes, that is also what I was taught. But that suggests the following model to me: 1. Volcanoes are caused by Circumstances X, Y, Z, whatever. 2. Collision of two tectonic plates causes Circumstances X. That is, I want the model of "volcanoes" to account for all volcanoes, not just most volcanoes. If we describe circumstances that are necessary and sufficient to create a volcano, we're done; the fact that the interaction of tectonic plates often creates those circumstances -- and even more often doesn't -- isn't really part of the model at all.

dredmorbius 6y ago
"Whatever" turns out to be a reasonably limited set of exceptions to tectonic boundary models. Plate tectonics describes and explains the overwhelming majority of known current volcanos and volcanic regions. Mantle plumes, which themselves drive tectonic activity, much the rest. The overall structure of the Earth, with a thin crust, plastic mantle, and hot core with temperatures resulting from both latent heat of gravitational formation and ongoing radioactive decay itself explains much and is entirely consistent with plate tectonics. The principle further exceptions might be simply thin crust, or penetrations by impactors --- the universe is complex, volcanos result from escape or exposure of interior magma to the surface by some mechanism. Gods hurling thunderbolts or smithing armour for other gods, for example, has scant evidence. I'm unaware of any specific terrestrial volcanoes not explained by tectonic or plume mechanisms. There are minor craters (e.g., Ubehebe crater in Death Valley) resulting from steam rather than magmatic bursts, but still driven by geothermal processes. https://en.wikipedia.org/wiki/Ubehebe_Crater https://en.wikipedia.org/wiki/Ubehebe_Crater Further we've now had evidence of similar mechanisms (or their lack) on other bodies, including the Moon (little tectonic activity, some faulting for other reasons, possibly validating Tethys impact formation hypothesis, possible recent volcanism https://coolinterestingstuff.com/volcanoes-erupted-on-the-moon-recently https://coolinterestingstuff.com/volcanoes-erupted-on-the-mo...), Mars (extinct volcanos, former tectonics), Venus (active volcanism, possible tectonics), Mercury (mixed, some faulting thought due to cooling and contraction), and Io (tidal-force induced volcanism), as well as other moons of Jupiter and Saturn.