Refining Late Holocene explosive eruption histories of the Main Ethiopian Rift with lake sediment tephra records

The Main Ethiopian Rift (MER) hosts a rapidly growing population exposed to eruption hazards from ∼60 active Holocene volcanoes. The geological record preserves significant information about the nature and frequency of past explosive volcanism in the rift, but the Holocene eruption record remains incomplete and its implications for contemporary volcanic hazards are yet to be fully understood. Here we use lake sediments preserved at four sites: Babogaya (MER), Haro Kori and Wergoba (southeastern Ethiopian plateau), and Dendi (western Ethiopian plateau) to constrain the Late Holocene tephrostratigraphic record. We focus on Lake Babogaya in the Bishoftu Volcanic Field which preserves 5 visible and 2 cryptotephra layers dating between 0.4 and 4.5 ka. Distal ash in this record is chemically correlated by major element composition to at least three eruptions of the Boset Volcanic Complex and two eruptions of the Corbetti Volcanic System in the last 5 ka, providing the first absolute age control for recent explosive activity of Boset. Ashfall originating from the 1.3–1.9 ka VEI 5 Wendo Koshe Younger Pumice eruption of Corbetti is identified in three records allowing re-estimation of total erupted volume for this event with improved distal constraints. The total erupted volume is >1.3 times larger than previous estimates, dispersing ∼4.0 km 3 (2.75–6.75 km 3 ) of tephra over ∼90,000 km 2 , and predicts ashfall within range of Addis Ababa. An additional visible tephra preserved at Haro Kori, dating to 2.3 ka BP, indicates another large-magnitude eruption of Corbetti occurred within the last 2.5 ka. These findings demonstrate the value of distal lake records for improving the regional eruption record of the MER, providing crucial controls on the timing and magnitude of recent rift volcanism. Ash dispersal from central rift volcanism is capable of inundating populous areas across central Ethiopia; our work supports more informed preparation for future volcanic ash hazards in a region undergoing rapid development. • Seven crypto/tephra layers are preserved in sediments from Lake Babogaya over 5 ka to present. • Several explosive eruptions of the Boset Volcanic Complex and Corbetti dispersed ash across the central rift. • First age estimates for recent explosive volcanism of Boset, with the Boset Pumice occurring at ∼600 years BP. • Updated dispersal and total erupted volume constraints for the Wendo Koshe Younger Pumice eruption of Corbetti.