Caldera subsidence in extensional tectonics

Abstract

We consider here the effect of extensional tectonics on the dynamics of large calderas. Active calderas are generally characterised by different periods of uplift and subsidence, in some cases spaced out by eruptions. Understanding of mechanisms which produces caldera uplift/subsidence is one of the main topics of volcanological research but is still a matter of debate. Using a simple conceptual model, we show analytically that the tectonic extension and its rate can produce the condition for the subsidence, in early stage, which in turn can also yield the magma migration (uplift) and, eventually, eruption. This work provides a possible hypothesis for caldera dynamic, which initiates due to chamber depressurisation and evolves towards potential conditions for magma re-mobilization as a consequence of tectonic loading. The conceptual model is also applied to the Campi Flegrei caldera (Italy), showing that the observed subsidence may be a result of extensional processes.