Is any or all of the effects of Earth's Carbuncle resistible with Parma or Might?
I'd say so, yes. The spell doesn't affect the target directly, but (like PoF) works its magic within the area protected by the maga's Parma Magica. Actually, the 4th bullet point under "Magic Resistance" (page 85) is a fairly good analog for how I picture that spell working. Basically, the earth still explodes upward as described, but since they're driven by magic, there's no wounding force behind the blow and thus no possibility of damage.
Of course, the earth and stones thrown up by the spell are coming back down due to natural motion so I suppose there is an argument to be made that the victim still takes damage from the spell, but I'd suggest halving it at the very least...
The question comes in with the Invisible Sling of Vilano (HoH:S 38) as it only give the starting movement to the stone and so is considered as nonmagical attack.
So it comes down if Earth's Carbuncle is just giving the starting force to the projectils or keep them influenced on theyr way up.
Both your responses represent the basic quandary I'm in. An argument could be made for both, I lean towards the Sling of Vilano argument as it's an explosion that expends the magical force immediately.
Juste readed the spell again and this line:
"Causes a 1-pace circle of ground to become jagged stone."
Says your have magical tranformed material what is allways resitsed
By Jove I think you've got it!
If its not aimed, its resisted. Any effect that bypasses resistance must be aimed. That's basically all you need to know about when something is resisted.
Also this is more than just damage. An effect that boxes someone in? Aimed if it traps magi. Destroys the earth beneath them? Aimed.
@Lamech its not that simple as you could transform something via magic to stone and then use Invisible Sling of Vilano on this stone resulting that the target still get his full magic resistance.
Or you use a area effect to initate the collaps of a cave then you don't need to aim but the stones still fall on theyr own so the effect is not aimed but still ignores magic resistance.
Restating this: it uses Muto as a requisite. Only pure Rego spell can bypass MR afaik. Myabe there are exceptions to confirm the rule. 
Wielding the Invisible Sling is i.e a pure Rego spell but the stone is constant moved by the spell and so the spell get resisted.
Doesn't contradict the "If it's not aimed it's resisted".
It can be both aimed and resisted (Amazons have to deal with that problem for everything they do) but it can't be neither/
It doesn't ignore the magic resistance of the cave, and, if you want to collapse specifically the part of the cave over someone's head, you're going to have to aim it.
If you're collapsing the whole cave you're using such a large AoE that the aiming is trivial, but you're still aiming it.
Tugdual didn't say that all Rego spells were unresisted, just that only Rego spells were unresisted.
As it happens, that's not actually quite right (there's an example perdo spell that causes a tree to collapse, with an aiming roll to pick the direction of collapse; and effects like creating a cage around someone are possible through aiming) but it's pretty close to it.
Right, I was thinking of the best way to say that.
Not sure if I'd require a roll of they were trapped in the cave. If the whole place ends up uninhabitable they probably just go straight to being trapped after taking impact damage. But if they have a chance of jumping through the window or dashing for the entrance I would roll aiming and defense. Of course the attacker would have a nice fat +12 to hit, but still.
Oh, right. Thanks for the exceptions. 
The only way I can actually picture that spell circumventing Parma Magica is that it shoots the stone ballistically, meaning it provides the energy to move it up, but natural gravity pulls it back down and thus hits its target with this force regardless of any magic resistance.
Otherwise it's just breaking the rules of how Magic Resistance works as laid out in the core rulebook.
As said, the carbuncle is resisted. However, that does not mean that you cannot create a version (another spell, really) that is Aimed and hence, not resisted. The damage would depend on what ground the target is standing on, since a bunch of mud moving up will cause few damage, while a pile of slate could do significant harm.
Cheers,
Xavi
The Rock is a Transformed substance (Muto Requisite) so it is going to be resisted.
The motive force is also a magical medium so also resisted.
Look at the examples in ARS5 of the magical jet of magical water vs the magical jet of natural water.
When the propelling force is magical, then the propelling force is resisted.
Had this simply launched natural mud at the resisting target rather then sharp rocks then he would become forcelessly covered in mud
A
No. The magically propelled mud stops dead the moment it touches Parma, since the only motive force it has is magical. So no "forcelessly covered in myd at all". Unless the mid comes from above, that is. If it comes horizontally or from below, it does not touch the magus at all.
Xavi
The rules state that magically propelled natural water would get the magi wet but with no force.
Thats exact the problem as the Rego Terram guidlines in HoH:S 38 stretch this a bit.
From how I understand the spells it is ignoring magic resistance if something could work as projectile even when the starting force to get it flying is from magic but constant moving it via magic is a no go.
Edit: Acording to HoH:S 35 there is a errata to the core rules that allows this.
For me the question was answered, i should have noticed the Muto Requisite; almost any Muto spell is resisted entirely as the Muto keeps it magical for the entirety of the spell.
The aimed part is also a good point about resistable spells. Now one last little quirk about this epll. Its target is Part, aren't most Target Part spells aimed? This doesn't change anything for Earth's Carbuncle being resisted though.