Big crack is evidence that East Africa could be splitting in two

Lucia Perez Diaz is a Postdoctoral Researcher at Fault Dynamics Research Group, Royal Holloway. The views expressed in this commentary are solely those of the writers. CNN is showcasing the work of The Conversation, a collaboration between journalists and academics to provide news analysis and commentary. The content is produced solely by The Conversation.

(CNN)A large crack, stretching several kilometres, made a sudden appearance recently in south-western Kenya.

The tear, which continues to grow, caused part of the Nairobi-Narok highway to collapse and was accompanied by seismic activity in the area.
The Earth is an ever-changing planet, even though in some respects change might be almost unnoticeable to us. Plate tectonics is a good example of this. But every now and again something dramatic happens and leads to renewed questions about the African continent splitting in two.
    The Earth's lithosphere (formed by the crust and the upper part of the mantle) is broken up into a number of tectonic plates.
      These plates are not static, but move relative to each other at varying speeds, "gliding" over a viscous asthenosphere.
      Exactly what mechanism or mechanisms are behind their movement is still debated, but are likely to include convection currents within the asthenosphere and the forces generated at the boundaries between plates.
      These forces do not simply move the plates around, they can also cause plates to rupture, forming a rift and potentially leading to the creation of new plate boundaries. The East African Rift system is an example of where this is currently happening.
      The East African Rift Valley stretc