Some ideas regarding volcanology in my world

[LonewandererD]

Yo, sorry about all of these questions but you smart little monkeys in the guild are a fountain of knowledge, a fountain I need to tap again. I’m planning a small series of maps centred on a palace built in the crater of an extinct volcano and need to run some concepts past you guys. What research I have done and what I what I was actually able to draw from the text I could understand these concepts are at least theoretically possible. However, my knowledge of science while a bit broad is not all that advanced as someone who would study certain areas specifically. Long story short are the concepts below believable, if not what flaws do I need to address.

Concept 1: I know that volcanoes can rise inside other extinct volcanoes, see Mt St. Helens, can a volcano rise on the edge of a volcano i.e. having the side of a caldera pushed up to form a second higher caldera? And if this second volcano collapsed in on itself would it destroy the previous caldera or could you actually have two caldera “rings” interlocked with each other, see picture 1.

Concept 2: While aforementioned volcanoes are extinct they sit on a volcanic hotspot. Underground rivers running into this hotspot become heated and rise through cracks and fissures in the earth into a large cavern underneath the “floor” of the second caldera. Here the water cools and empties out of the cavern causing a waterfall, or several small ones, to run down the side of the caldera and forming a lake in the base of the first caldera which after hundreds of years has formed a river that runs out to the sea, see picture 2. If enough water can be forced into the cavern at the height of the caldera can this system be sustainable?

Concept 3: Aware of the hot springs in the area the locals are able to “tap” one of them, forcing steam and water vapour to rise through a series of pipes set in the walls of the palace. This water either empties out into basins hidden in the walls where it cools or is forced into wall cavities where it heats the walls and therefore the rooms of the palace. The water held in the basins is either used for drinking fountains or to fill up private bathtubs, small fires are lit in chambers under the floor to heat the water back up again to the desired temperature, only a few of these exist to serve the royalty and other high dignitaries, everyone else uses the palaces bathhouse. What steam that can escape is released through vents in the roof of the palace. The steam that cools into water is carried away by pipes where it is either used to wash away waste from privies, creating a simple form of running water waste removal, or forced into siphons to power the palace fountains before being carried away from the palace via underground pipes with the rest of the waste water. These systems are separate from each other to prevent waste water contaminating bathing/drinking/fountain water, the pipes carrying the water is set on a downwards slope and have small ledges in them to prevent water flowing back up unless there is a block of some kind. Small flaps and valves in the walls can be adjusted to redirect the steam and water to certain areas of the palace where they are needed most. Will try to provide a picture if I can.

So, would these ideas work?

-D-