It is the weight of the edifice exceeding its material strength, with the additional stresses of the magma inflating the internal regions of the edifice, that can generate the initial cracking around a developing volcanic summit. Additionally, tectonic activity such as normal faulting is also commonly associated with formation of rifts along volcanic flanks.
It is the weight of the structure surpassing its material capacity, combined with the extra stresses from magma expanding within the internal regions of the structure, that can initiate cracking around a developing volcanic peak. Furthermore, tectonic activity such as normal faulting is also frequently linked to the formation of rifts along volcanic flanks.