Well, that entirely depends on what kind of volcano central Eastmarch is, really. Since much of Eastmarch is very reminiscent of Yellowstone's volcanic features, the vast plain is very likely a wide, open caldera. I suspect Bonestrewn Crest is a resurgent dome within the larger caldera. If this is the case, then its elevation should be closely monitored by the Jarl as the dome is formed by the increase and decrease in volume of magma beneath the surface.
Given Eastmarch's size, the explosion of a caldera of that size would be nothing short of catastrophic for not only Skyrim, but any of the provinces surrounding the area. This is namely due to the fact that historically, explosive calderas (like Yellowstone, and in this case Eastmarch) tend to cause massive eruptions, expelling more matter than most mountain-shaped volcanoes (indeed, those are actually safer as they have thicker lava that flows more slowly and expel less gas and ash). It would cause greater devastation over a longer period of time than any Vesuvian volcano. The last time Yellowstone erupted (some half a million years ago), ash covered over one-third of the US (where as Mt. St Helen's eruption only covered the breadth of a few miles).
Well, that entirely depends on what kind of volcano central Eastmarch is, really. Since much of Eastmarch is very reminiscent of Yellowstone's volcanic features, the vast plain is very likely a wide, open caldera. I suspect Bonestrewn Crest is a resurgent dome within the larger caldera. If this is the case, then its elevation should be closely monitored by the Jarl as the dome is formed by the increase and decrease in volume of magma beneath the surface.
Given Eastmarch's size, the explosion of a caldera of that size would be nothing short of catastrophic for not only Skyrim, but any of the provinces surrounding the area. This is namely due to the fact that historically, explosive calderas (like Yellowstone, and in this case Eastmarch) tend to cause massive eruptions, expelling more matter than most mountain-shaped volcanoes (indeed, those are actually safer as they have thicker lava that flows more slowly and expel less gas and ash). It would cause greater devastation over a longer period of time than any Vesuvian volcano. The last time Yellowstone erupted (some half a million years ago), ash covered over one-third of the US (where as Mt. St Helen's eruption only covered the breadth of a few miles).
I think that this is an interesting idea, but I don't believe that bonestrewn crest is a volcano. The mineral pools have existed before the red year, I know that they definitely been around since the second era, as they appear in the elder scrolls online in the interactive map of Eastmarch. Also, the word wall at the top of the mountain has been there since the myrethic era. If a volcano existed there and has buried the nearby ruins in ash as you say, then why would a word wall, constructed at the same time as the ruins, still be intact at the top of the mountain. Finally, the Eldergleam sanctuary exists below the hot springs, at the foot of the bonestrewn crest, and going under the mountain, and there is no evidence of any magma or volcanic heat source within the sanctuary.
I think that this is an interesting idea, but I don't believe that bonestrewn crest is a volcano. The mineral pools have existed before the red year, I know that they definitely been around since the second era, as they appear in the elder scrolls online in the interactive map of Eastmarch. Also, the word wall at the top of the mountain has been there since the myrethic era. If a volcano existed there and has buried the nearby ruins in ash as you say, then why would a word wall, constructed at the same time as the ruins, still be intact at the top of the mountain. Finally, the Eldergleam sanctuary exists below the hot springs, at the foot of the bonestrewn crest, and going under the mountain, and there is no evidence of any magma or volcanic heat source within the sanctuary.
Actually, couldn't the eldergleam sanctuary be the result of fertile, ash-enriched soil and high levels of CO2 generated by the burning of things beneath the earth of Eastmarch? I think this explains why the plants and fauna in that area are so healthy. Not the influence of an Aedra ( unless Kynareth is influencing the formation of geo-thermal energy), but Nirn's natural cadence of tectonic activity. I'd love to see a map of the planet's fault lines and tectonic activity over the vast period of it's existence.
Actually, couldn't the eldergleam sanctuary be the result of fertile, ash-enriched soil and high levels of CO2 generated by the burning of things beneath the earth of Eastmarch? I think this explains why the plants and fauna in that area are so healthy. Not the influence of an Aedra ( unless Kynareth is influencing the formation of geo-thermal energy), but Nirn's natural cadence of tectonic activity. I'd love to see a map of the planet's fault lines and tectonic activity over the vast period of it's existence.