There are several hypotheses touted as to why EARS began, with the most popular being that a superheated plume – or several smaller plumes – of mantle material is rising up into the crust beneath that very spot. Although one 2014 review paper said that “its deep origins remain poorly understood,” a single, massive plume is the most probable cause.
Either way, there are consequences to having an active rift zone.
Some parts of the region have subsided over the past few million years; others have been uplifted. The splitting has fragmented the region so acutely that it’s thought to have created tectonic microplates, like the Victoria and Rovuma plates, in its wake. The geochemistry beneath the EARS is also spectacularly bizarre, creating a range of otherworldly volcanoes.
Another consequence, perhaps, is the surficial activity noted in these reports.
Back in 2005, for example, an 8-meter (26-foot) gap opened across a 60-kilometer (37-mile) stretch in just 10 days. This crevasse was created when magma heading to Ethiopia’s Dabbahu volcano was diverted underground, which cooled, froze, and was forced up to the surface, causing a crack. It continued to grow because the EARS just keeps on rifting.
When it comes to the cracks in this part of Kenya, then, either a similar magmatic diversion event has occurred – after all, it does happen to be surrounded by several volcanoes – or there has been a sudden, probably brief jump in the local spreading rate. Or, as aforementioned, it's an erosional feature.
Until more details emerge, however, this remains somewhat speculative.
Update: Dr James Hammond, a geophysicist at Birkbeck, University of London, told IFLScience that it's unclear what this phenomenon represents.
"I don’t think this is related to magma injection, it’s not the same as Dabbahu. In Dabbahu, it was not a simple crack, but a whole series of faults that moved," he said. "Equally, I’m not sure a local increase in spreading rate is right."
"I am not sure what has caused this," he added. "Were any earthquakes felt? If not then it seems unlikely to be tectonic or volcanic."