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-

[waldronate]

Take a look at the Yellowstone caldera system. It's a series of overlapping calderas with a great deal of geothermal activity.

From your diagram, I'm not sure what the vertical extent is, but what you've proposed is generally plausible. The river would probably not be a single channel, but rather a set of smaller channels rising through fractures in the rock. How large the total river might be is, of course, a matter of preference.

Depending on the particulars of the mountain, you might also have a glacier at the top whose melt supplies a large portion of the total water flow.

With regards to the palace, it is probably easier to work with hot water than with steam. Steam implies pressure and volcanic gasses tend to be pretty corrosive, which would lead to lots of nasty pipe bursts.

I gather from the descriptions that one of the important parts here is the presence of lots of steam and fumes that will wreath the architecture. Depending on how far away from the volcano the palace resides, you might be able to channel a hot aqueduct and a cold aqueduct into the palace area. Heating with steam can be a problem because the steam can quite hot, heating the rooms hotter than intended. Having a separate cold system will allow for quicker adjustment of temperature and provides a good heat sink for condensing the steam.

[Hungry Donner]

Off hand I'm not aware of any hot springs/water falls on the side of a volcano like that, but I don't see any reason it couldn't work.

Overlapping calderas aren't common in traditional volcanoes (at least not on Earth) but they work as well. In fact I believe the Azores have a set up like this (if not they're still gorgeous to look at).

[7thDirection]

For Concept 1: Mount St Helens is a good resource, however, I've always been tickled by the Maug Islands archipelago. The islands form the north, west and east edges of a caldera volcano. If you look at the Maug Islands inset on NOAA Chart 81092, you can see the bathymetry in the lagoon. You can see at one point, the volcano was still active for a little while because of the shoaler depths in the middle. Here's a video of taken of the islands: Maug Islands.

Concept 2: I can't think of any place that has geological makeup like this... Yellowstone has overlapping calderas, but they are large and not very noticeable. I'm thinking that the formation of the second caldera would destroy the first, or at least, blow out the nearest wall. I'm not sure how you would get the cross section diagram you have attached with your post considering caves are formed in sedimentary rock, not volcanic rock - unless the cave is an empty Magma Reservoir, which, I would think would be in the Earth's crust (not in the volcano itself). I did a search for geothermal caverns and the first place I came up with is Acquasanta Terme in central Italy (and even that doesn't seem to fit your description well).

For Concept 3: I would definitely look at maps of the Yellowstone Park region. The geysers, hot springs, mudpots and fumaroles are all because of the volcanism below.


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