<P> Active volcanos include Erta Ale, DallaFilla, and Ol Doinyo Lengai, the former of which is a continuously active basaltic shield volcano in the Afar Region of northeastern Ethiopia . When DallaFilla erupted in 2008 it was the largest volcanic eruption in Ethiopia in recorded history . The Ol Doinyo Lengai volcano is currently the only active natrocarbonatite volcano in the world . The magma contains almost no silica, making the flow viscosity extremely low . "Its lava fountains crystallize in midair then shatter like glass" according to the National Geographic . Approximately 50 volcanic structures in Ethiopia alone have documented activity since the onset of the Holocene . </P> <P> The EAR is the largest seismically active rift system on Earth today . The majority of earthquakes occur near the Afar Depression, with the largest earthquakes typically occurring along or near major border faults . Seismic events in the past century are estimated to have reached a maximum moment magnitude of 7.0 . The seismicity trends parallel to the rift system, with a shallow focal depth of 12--15 km (7.5--9.3 mi) beneath the rift axis . Further away from the rift axis, focal depths can reach depths of over 30 km (19 mi). Focal mechanism solutions strike NE and frequently demonstrate normal dip - slip faults, although left - lateral motion is also observed . </P> <P> The Rift Valley in East Africa has been a rich source of hominid fossils that allow the study of human evolution . The rapidly eroding highlands quickly filled the valley with sediments, creating a favorable environment for the preservation of remains . The bones of several hominid ancestors of modern humans have been found here, including those of "Lucy", a partial australopithecine skeleton discovered by anthropologist Donald Johanson dating back over 3 million years . Richard and Mary Leakey have done significant work in this region also . More recently, two other hominid ancestors have been discovered here: a 10 - million - year - old ape called Chororapithecus abyssinicus, found in the Afar rift in eastern Ethiopia, and Nakalipithecus nakayamai, which is also 10 million years old . </P>

There is a divergent plate boundary within the region of east africa