10 October 2016
Meru Volcano, Tanzania
Meru is a 4565 m high volcano located on the East African Rift in Tanzania. In a paper just published online in Landslides, Delcamp et al (2016) examine an enormous debris avalanche deposit, known as Momella, that was formed when the the eastern flank of the volcano collapsed about 9000 years ago. The horseshoe-shaped scar of this collapse event is very evident on Google Earth:
The collapse event was truly epic. The paper attempts to determine the volume of the debris flow deposit, and concludes that it was about 20 cubic kilometres – that is 20 billion cubic metres or about 55 billion tonnes of rock. To put that in perspective, if the debris were piled onto a plot the size of an average city block (about 10,000 square metres), the pile would be 2000 kilometres high! The deposit covers an area of about 1250 square kilometres, as shown in this map from the paper. I have put a Google Earth image alongside for comparison:
As the map shows, the enormous Momella landslide deposit is not the only one in the vicinity of Meru volcano – indeed there are at least two others, although these are smaller. According to Delcamp et al (2016), the Momella landslide had a fall height of 3.4 km and a runout distance of 49 kilometres, giving it exceptional mobility. Interestingly, the paper suggests that the presence of water probably played a key role in the exceptional mobility of the landslide.
This is another example of these most enormous and catastrophic of all landslides. Such events are exceptionally difficult to study because of the huge area that they cover, and the difficulty of obtaining good outcrops of the deposit. I think this particular example is probably not widely known, so this new, impressive, paper is most welcome.
Delcamp, A., Kervyn, M., Benbakkar, M., Kwelwa, S. and Peter, D. 2016. Large volcanic landslide and debris avalanche deposit at Meru, Tanzania. Landslides (2016). doi:10.1007/s10346-016-0757-8
Other posts that may be of interest
- Rockfalls shaking a volcanic lava dome apart (including a dramatic video)
- Geological evidence for a large landslide in Tenerife
- Volcanic landslide in the Democratic Republic of Congo
- The Casita landslide revisited
- Volcanic flank collapse and tsunamis