The Leaning Puy de Dôme (Auvergne, France) tilted by shallow intrusions

Abstract

Monogenetic lava domes are a special type of volcanic structure, prone to mass wasting and explosive eruptions. The iconic Puy de Dôme (Chaîne des Puys, Auvergne)—which gave its name to ‘dome’ landforms—is asymmetric, with one side steeper than the other. The Puy de Dôme grew rapidly in one simple pulse from a bulging shallow intrusion, the Petit Puy de Dôme, and then solidified in situ. Using mapping and paleomagnetism we find that it was subsequently tilted by ~17° to the southwest by further surface-bulging inflation of the Petit Puy de Dôme intrusion. During the tilting, there were landslides and a final small phreatomagmatic eruption. The dome’s history verges on polygenetic, spanning several hundred years of intrusion and eruption, extending hazard periods for such activity. We find other intrusive uplifts with paired domes and tilted cones both in the Chaîne des Puys and in other monogenetic and polygenetic systems.