A regional InSAR survey of Central Andean Volcanoes found that a 20 km diameter area surrounding Cerro Overo was subsiding between 1992 and 2003 at up to 4 mm/year (Henderson & Pritchard, 2013). Between 2003 and 2005 this subsidence transitioned to uplift, and between 2005 and 2011 the volcano was observed to be uplifting at up to 5 mm/year. Based on the similar spatial extent and magnitude of the subsidence and uplift, the authors suggest that both are controlled by a single reversible mechanism involving fluid accumulation and loss within the crust at approximately 10 km depth (Henderson & Pritchard, 2013).