Volcanic edifice weakening via decarbonation: A self-limiting process?

The inherent instability of volcanic edifices, and their
resultant propensity for catastrophic collapse, is a constant
source of volcanic risk. Structural instability of volcanic
edifices may be amplified by the presence of carbonate rocks
in the sub-volcanic strata, due to the debilitating response of
carbonates to thermally-induced alteration. Nonetheless,
decarbonation reactions (the primary weakening mechanism),
may stall when the system becomes buffered by rising
levels of a reaction product, carbon dioxide. Such
thermodynamic stalling might be inferred to serve to circumvent
the weakness of volcanic structures. However, the
present study shows that, even when decarbonation is halted,
rock physical properties continue to degrade due to thermal
microcracking. Furthermore, as a result, the pathways for
the escape of carbon dioxide are numerous within a volcanic
edifice. Therefore, in the case of an edifice with a subvolcanic
sedimentary basement, the generation of carbon
dioxide via decarbonation is unlikely to hinder its impact on
instability, and thus potentially devastating flank collapse.