Nyiragongo volcano (DR Congo): fracture opens new vent inside crater - precursor of possible flank eruption?
Tuesday Mar 08, 2016 13:20 PM | BY: T
View of the crater of Nyiragongo on 1 or 2 March with the lava lake and the new vent at the NE margin of the crater floor (image: OVG)
Some very unusual and alarming events have been taking place at the volcano recently: A new eruptive vent opened at the northeastern end of the lowest crater terrace, outside the active lava lake (which had been in place since 2002) and just beneath the near vertical crater walls..
The new vent on the NE end of the crater floor on 1 or 2 March (OVG)
According to a preliminary report of the Goma Volcano Observatory (GVO) who visited the volcano during 1-2 March, the new vent is now forming a second lava lake. Images from a visit of GVO staff show a spatter cone erupting fresh lava flows that pooled onto the crater floor.
GVO reported that since the end of February, activity at the volcano has been more intense than usual. In particular, starting from 04 am on 29 February, local inhabitants began to hear frequent rumblings coming from the volcano almost every minute. Likely, these were caused by the opening of the new dike (fracture occupied as pathway for the new magma) and associated rockfalls inside the crater (the vent is directly located near almost vertical walls). It is important to note as GVO's report mentions, that the location of the new vent is on the east-trending fracture zone that connects the summit vent of Nyiragongo with the prominent flank cone Baruta to the northeast of the main edifice, near the village of Kibumba.
This rift zone (along with the southern rift zone extending towards Goma town) is one of the most prone locations of the volcano's dangerous flank eruptions.
When these occur, the volcano's edifice is ruptured laterally, allowing magma to drain outside. Such eruptions have been occurring at intervals of few decades typically. They usually drain very large volumes of very fluid, and hence, unusually fast flowing lava from the lake in short time. The results of the past two such eruptions in 1977 and 2002 were catastrophic: they killed more than 1000 people, destroyed dozends of villages and a large part of Goma town (in 2002).
Whether or not the current developments are precursor of a new eruption from Nyiragongo's flanks is difficult to say, but the appearance of the new vent tells that an extensional movement has taken place on this fracture zone, something that is certainly alarming.
Links / Sources:
Links / Sources:
- RAPPORT PRELIMINAIRE DES OBSERVATIONS DE L’ACTIVITE DU VOLCAN NYIRAGONGO DU 29 FEVRIER AU 2 MARS 2016 (OVG report)
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