Wendy Bohon, PhD 🌏 Profile picture
Apr 4, 2018 17 tweets 5 min read Twitter logo Read on Twitter
So here are my extended thoughts on the #KenyaCrack, or #KenyaGully if you prefer. The narrative that’s going around is that this is a great gash that opened up and is splitting Africa in two. That's incorrect. Africa is being split but very slowly. This is called rifting.
Riting is definitely happening in Africa. This is not really disputed. There is lots of scientific literature on the subject. sp.lyellcollection.org/content/420/1/…
But rifting occurs over a very long period of time, like millions and millions of years.
Rifting progresses through earthquakes and volcanic eruptions and other geologic forces. Here is an animation showing how the crust thins before it splits. (This example is from the US, but the process is similar)
Many things can make a crack that looks like the crack in Kenya. Earthquakes, volcanic events and erosion are the most likely. Earthquakes and volcanic eruptions are active rifting events.
There haven’t been any recent #earthquakes detected in this area that we know of. Seismic networks here are sparse but we would likely have detected any earthquake large enough to disrupt the ground this way.
You can look up recent and historic earthquakes here. Use the control on the right to search by location and time. ds.iris.edu/ieb/
Additionally, there is no up and down motion on either side of the crack, which is what we would expect if this were the result of an earthquake in this area.
I am also not aware of any recent volcanic activity in the area. Here is an example of volcanism associated with active rifting in the Afar region of Africa. Super different. agupubs.onlinelibrary.wiley.com/doi/full/10.10…
However, there has been heavy rainfall and flooding in Kenya. nation.co.ke/news/Heavy-dow…
Heavy rains in other parts of the world sometimes reveal features that look like this. They can be huge. (Image attribution in article) Looks similar, right?azgs.arizona.edu/center-natural…
Most geoscientists agree that the rains caused this feature, not a recent earthquake or recent volcanic activity. What we don’t know is a more subtle thing – why it formed exactly where it did and what lies under it.
It may have formed over an older extensional feature that filled in with soft soil that was easy to wash away. It may have formed over a fault. Both of things are tangentially related to rifting, but neither of those things are active at this moment.
We need more data, evidence and direct observations from scientists on the ground in order to figure out the geologic subtlies of this feature, which are only interesting to geologists.
So is rifting happening in Africa? Yes. Is this direct evidence of it? Not really. There’s plenty of other amazing and phenomenal evidence of active rifting in Africa. Share in the comments!
Sorry about the problems with the previous thread @EricFielding @janinekrippner et al. That's what I get for trying to multitask!
Probably. I should have said probably only interesting to geologists. I’m sure there are others out there interested in arguing about the underlying casual mechanism, whether it be differential soil compaction or a buried fault or whatever.
Here’s some good info about EARS-the East African Rift! geology.com/articles/east-…

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