Can we estimate volumes of volcanic ash supply to the oceans?

HALLER, MJ

Rimouski

Workshop; Workshop on the PROMESSe project: results and opportunities; 2017

Université du Québec à Rimouski

For the Holocene of the Southern Andes, there are records of five eruptions with VEI = 5, three eruptions with VEI = 6 and one eruption with VEI = 7. We know that the record is incomplete, but equal is a relatively low number of major eruptions. On the other hand, the distance from the origin to the ocean causes that a large proportion of the tephra deposits on the continent, so it is not expected to find thick deposits (≈5-10 cm) of tephra in the South Atlantic cores. A (conservative) estimation is that the South Andean Volcanic Zone produced an ash mass flux of 93Tn into the oceans during the Holocene. That is 9.3 kg/year.However, it is expected to find cryptotephra throughout the sedimentary column, detectable by magnetic measurements and the finding of volcanic shards in the sediments.