The January 2002 eruption of Nyiragongo volcano (DRC) captured by InSAR

On 17^th January 2002, Nyiragongo erupted along an approximately 20 km long fracture network extending from the volcano to the city of Goma and its airport. The event was captured by InSAR data from the ERS-2 and RADARSAT-1 satellites acquired in three different geometries. These data show complex ground displacements, with several overlapping fringe patterns, associated to a combination of sources of magmatic and tectonics origins. A combination of 3D numerical modeling and inversions is used in order to interpret these displacements. Synthetic tests indicate that with one to three INSAR geometries, the best fit and mean models are within the confidence intervals whether the source of displacements is a single dike, a dike combined with a west dipping normal fault or a dike combined with an ellipsoid. Increasing the number of InSAR geometries makes the confidence intervals smaller and the inversions faster. At this stage of the study, only the area close to the eruptive fissures was analyzed assuming displacements were caused by a single dike. The best-fit dike model obtained with a simultaneous inversion of the three InSAR geometries is subvertical, and has a low overpressure. Both characteristics are consistent with the rift context.