Sulphuric Bubble?

Yesterday, a huge and tremendously powerful earthquake struck Korth. Some buildings were damaged, and mountains had fissures open up in them. Since then, the buildings have been repaired and the fissures closed. This earthquake was too violent to be natural, and on the day Seran was blasting away some rock in search of ores. These two events may be linked, as Seran may have accidentally ignited some sort of flammable ore or material in the rock, which would have acted like a fuse, which would lead to a sulfuric bubble, which would explode, since sulfur is highly explosive. This bubble would have needed to be incredibly large, however, due to the pure power of this earthquake. This has lead me to believe that Korth may have (Or quite possibly still does) reside atop a giant bubble of sulfur, which I have named the underground Korthic Gas Lake. Of coarse, there is no proof to suggest this is definite at this time, but it is one theory that seems highly possible. Some elves however may believe this is the wrath of some sort of 'God of Earth.' I am a prolixian, so i do not believe this, however it might be possible. I request that you do not deny or attempt to disprove any theories on what caused this earthquake, as it is currently unknown what did. We require theories to see what it might be, then we can go out, test these theories, and find out which is true.

It has been known since the Dragon Wars that there are vast underground tunnels in Korth, the dragon armies would reside there. No doubt there are caverns as well. I only knew of one entrance ; it is in Tir'an not far from the orc's village.

Stayjit, you continue to surprise me in how you can forget the most important details. How would these tunnels and caverns be connected to the earthquakes?

Underground caverns collapse, or they fill with magma. Tunells provide vents for magma flow, They cause localized earthquakes.