Geodetic Monitoring of the Recent Activity and the Dome Forming Eruption at Nevado del Ruiz (Colombia), 2010-2023

Nevado del Ruiz volcano in Colombia is known for the catastrophic eruption of 1985 that destroyed the villages of Armero and Chinchiná. This was not its first destructive event; similar eruptions occurred in 1595 and 1845. Unfortunately, the sparse geodetic data available in 1985 did not provide a clear warning of an impending eruption. Since 1985, geodetic monitoring has evolved, incorporating tilt, GNSS and InSAR. Combined with seismic, geochemical, and geological monitoring, these techniques have enhanced the understanding of the volcano, improved hazards assessment and mitigated the risk from the eruptions of 1989, 2012, and 2015-2019, as well as the unrest over the last 11 years. Modeling of deformation data over the past 13 years reveals complex interactions between local and regional magma reservoirs. Before February 2012, the volcano deflated, initially thought to be due to gravitational collapse of the edifice, but now attributed to the depressurization of a shallow magma reservoir. This reservoir has been feeding ash emissions, gas release (2012-2023), and the dome forming eruption (2015-2019). The inflation of the volcanic edifice from 2012 to 2023 is linked to a deep pressurization source beneath the Nevado de Santa Isabel volcano, about 9 km southwest of Nevado del Ruiz.