Long-term monitoring of long-period seismicity and space-based SO2 observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)

Magma ascent that may lead to an eruption is commonly accompanied by variations of long-period seismic activity and SO2 degassing. Space-based measurements of SO2 emission rates represent a rapidly emerging and highly convenient approach for volcano monitoring; however, combining these long-term remote sensing observations with seismic data is still rare and, in particular, the potential of such a multidisciplinary approach as volcano monitoring tool remains largely unexplored. Here shallow magmatic activity and magma migration patterns at the two closely located African volcanoes Nyiragongo and Nyamulagira are inferred from a nearly 3 years long SO2 emissions record and seismic observations between April 2014 and February 2017. The discrimination of magma movements into shallow plumbing systems allows for signs of volcanic unrest to be deciphered on a daily time scale, even with limited instrumentation on site.