The relatively young volcanoes like Mole Hill are thus the result of magma that seeped up through the cracks in the overlying rock, in essence further weakening pre-existing faults on the way up. (scientificamerican.com)
Arenal Volcano is considered a very young volcano that first erupted in 1968. (caravan.com)
Katmai's volatile young volcano, Novarupta, erupted in such a manner in 1912, and it left behind compelling proof of its explosive might. (nps.gov)