Coppola, D; Cigolini, C (2013). Thermal regimes and effusive trends at Nyamuragira volcano (DRC) from MODIS infrared data. BULLETIN OF VOLCANOLOGY, 75(8), 744.
Nyamuragira volcano is one of the most active African volcanoes. Eruptions have been occurring every 34 years throughout the last century. Here, we analyse satellite infrared data, collected by MODIS sensor to estimate the volcanic radiative power (VRP, in W) and energy (VRE; in J) released during the 2001, 2002, 2004, 2006-2007, 2010 and 2011-2012 eruptions. Based on the statistical distribution of VRP measurements, we found that thermal emissions at Nyamuragira fall into three distinct radiating regimes. The high-radiating regime occurs during the emplacement of poorly insulated lava flows and characterise most of the effusive activity. The moderate-radiating regime is associated with open-vent activity (Strombolian explosions and/or lava lake activity) eventually accompanied by the emplacement of short-lived and well-insulated flows. A third radiating regime (low-radiating regime) occurs during periods, which may last weeks to months, that follow each eruption and are associated with the cooling of the effused lava flows. By applying the radiant density approach to MODIS-derived VRP we also estimated the time-averaged lava discharge rates (TADR; in m(3) s(-1)) and we analysed the effusive trends of the above eruptions. We found that the transition between the effusive and open-vent activity typically takes place when TADR reduces to low values (<5 m(3) s(-1)) and marks a change in the eruptive style of the volcano. Finally, we observed a clear correlation between the volume of erupted lava and its cooling time. This suggests that the average thickness of the analysed lava flows is more variable than previously thought and sheds light on the uncertainty in calculating erupted volumes assuming that lava flow areas have uniform thickness.