Models of the Formation of the 29 February 2016 New Spatter Cone Inside Mount Nyiragongo

A new and unusual eruptive event occurred on 29 February 2016 within the summit crater of the Mount Nyiragongo volcano. Based on field campaigns performed between July 2015 and September 2017, and building on a previously published buoyancy‐driven bidirectional magma flow model explaining the progression of Mount Nyiragongo lava lake level, we provide the first quantitative estimations of volumes of erupted lava outpouring from the new spatter cone. Besides matching field data of the lava lake level covering the period December 2002 to September 2017, numerical solutions of the model reveal that the most probable dike path is one originating from the shallow magma reservoir, and not from the lava lake or branching from its feeding conduit. According to these simulations, the reservoir and erupted lava volumes are respectively estimated to the order of 10 km3 and 20 M m3. Magma overpressure at the level of the shallow reservoir is estimated in the range 12 to 16 MPa, high enough to potentially initiate new erupting events.