Abstract

The volcanoes of the Ethiopian Rift Valley are some of the least studied on Earth. Of the sixty-five currently active volcanoes in the region, forty-nine have no recorded historical eruptions. Accessing these volcanoes can prove a logistical challenge, and poor exposure at the volcano may hinder investigation of past eruption frequency and magnitude. To address this shortfall, we study sediment cores from seven Ethiopian lakes and construct the region’s first Holocene record of volcanism.

Volcanic ash (tephra) preserved in these stratigraphically-resolved lake sequences catalogue explosive eruptions through time. A tephra layer can be traced to its volcanic source and identified at different lake sites based on its geochemistry, allowing the tephra dispersal to be mapped. Lake sediments are also well-suited to radiocarbon dating, and these dates used to build Bayesian age models and understand the timing of past eruptions.

Our first eruption record reveals that Ethiopian volcanoes have erupted frequently and explosively throughout the Holocene, and therefore present a real, previously underestimated risk, to the rapidly developing population. Lake sediment tephra records show significant potential for reconstructing past volcanism throughout East Africa, work essential to clarifying and reducing today’s volcanic hazards.