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Abstract The East African Rift is one of Earth’s largest continental landforms. It is recognized as a critical region for understanding hominin evolution yet has also undergone important transformation through ongoing tectonic and volcanic activity. An understanding of the interplay of rift kinematics, magma genesis and geomorphic evolution requires firm geochronology but this has been lacking for much of the East African Rift. Here we present detailed stratigraphic observations and high-precision 40Ar/39Ar ages for major volcanic units in the Central Main Ethiopian Rift. Our new data identify a volumetrically major episode of explosive volcanism between circa 3.85–3.42 million years ago, after aproximately 5-million years-long quiescence. Four other pulses followed but with intensity and magnitude declining over time. We suggest that the observed temporal clustering and the pulsatory volcanic activity may have influenced environmental conditions in the area, with possible implications for hominin evolution.

Abstract Mediterranean climates are characterized by warm, dry summers and mild, rainy winters. Previous studies suggest that over the last 1.36 Myr, Mediterranean winter rainfalls were in phase with the African monsoon. Here we present a high-resolution terrestrial and marine dataset for the Marine Isotope Stage 17 interglacial (Middle Pleistocene) from Southern Italy, showing that precipitation rates and regimes in the central Mediterranean varied independently of the monsoon system. Specifically, events of extreme summer precipitation were promoted by increased regional insolation rates and/or extratropical cyclones, and their magnitude was further enhanced by the advection of cool and humid North Atlantic air during stadials. Our findings provide new information on the short- to mid-term natural hydroclimatic variability of the Mediterranean basin, and offer new critical insights on land–ocean interactions at the regional scale by complementing previous analyses on the displacement of storm tracks toward southern Europe.

Continuous continental rift zones evolve from enigmatic interactions between individual propagating rift segments. Here, the authors document progressive focusing of tectonic and magmatic activity caused by interactions between the Kenyan and Ethiopian rift segments of the East African Rift.