The Nyiragongo volcano, near Goma, in the eastern Democratic Republic of Congo, no longer seems threatening. Volcanologist Benoît Smets looks back on this eruption that surprised everyone, even though we knew this volcano could erupt one day or another
The lava flow has ceased just before you arrive in the city. Last night, its unexpected outbreak threw the inhabitants of Goma on the roads, the people fled out of the city and even to neighboring Rwanda. Panic movements have caused accidents, several deaths are to be regretted, the official record is consolidated.
Benoît Smets is a researcher at the Royal Museum for Central Africa in Tervuren and a professor at the University of Brussels. For the past fifteen years he has worked with the volcanoes in the area, especially Nyiragongo, in collaboration with the Goma Volcanological Observatory.
There were no warning signs telling us that there would be a big change in Nyiragongo. You should know that these are volcanoes – both Nyiragongo and its neighbor, Nyamuragira – that show clear warning signs, seen in seismicity, in earthquakes, usually a few tens of minutes or a few hours before the event. And then we did not really have any clear signs, which surprised us. We did not expect at all.
And what are these signs that do not appear?
For example, it is characteristic of Nyiragongo that it has a lava lake in its main crater and one would have expected to have extremely violent variations of this lava lake, seismic activity associated with the lava lake and possibly be tectonic earthquakes, therefore brittle earthquakes, with felt sizes, which would come before the outbreak. And there, in fact, this kind of seismicity happened rather afterwards. So it seems like it really was a surface eruption and then a deeper seismic activity with contributions from magma, but that’s not yet confirmed, because we only have automatic results. Detailed analyzes of seismic measurements have not yet been made.
And from what we could see, could it have been worse?
The fact that there were no major predecessors already says that there is probably no major eruption, as we had in January 2002. The configuration of the length of the lava flow. What happened is more like what we had in 1977. It is an outbreak that is a little less violent. I think we were lucky enough to have a lava flow that stopped at Goma’s gates. Although it unfortunately invaded inhabited areas, it was still limited to the northern part of the city and it did not return to the city center, where the damage would have been much greater.
And by the way, what can we expect?
This is a good question, because we only know about two historical volcanic eruptions, 1977 and 2002. We now have a case that seems a little different, so it is difficult to interpret. From what we see now, I do not think we would have any surface activity again. On the other hand, seismic activity continues in depth. So we do not yet know exactly what is happening, we need to analyze this activity in detail. But a priori I would say that the eruption on the surface is over. .
