Using ice cores to constrain parameters of eruptions during the 7th Century of the Common Era: challenges and opportunities

Ice cores provide a valuable archive of volcanism in the pre-satellite era, which can be used to understand timing, hazards and climate impact of past explosive eruptions. Sulfur isotope analysis of volcanic aerosols deposited and preserved in ice cores are used to constrain plume heights, source latitudes and inform stratospheric sulfur loading, while identification and geochemical analysis of microscopic ash particles can link ice-core volcanic deposits to specific eruptive sources. These techniques have enabled researchers to identify eruptive sources and characteristics of numerous eruptions recorded in ice cores, often targeting large, explosive events associated with climate forcing or widespread ash dispersal. However, the vast majority of the ice core eruption archive is yet to be explored, and there is much to be done to utilise the record to benefit volcanology research.

An important period of large, climate-impacting volcanic eruptions occurs in the 7^th Century of the Common Era. Historical eruption records are poor during this time period, but by targeting prominent sulfate and tephra deposits in Greenland ice core TUNU2013, we better constrain source parameters of three major eruptions in this century. As well as providing new insights into climate-forcing eruptions occurring in 626 and 682 CE, we identify the Newberry Pumice tephra from the Big Obsidian eruptive period of Newberry Volcano (Oregon, USA). This finding provides a new and precise ice-core chronology date for the Newberry Pumice and extends the known plume transport distance to Greenland.

These results demonstrate the wealth of data about individual volcanic eruptions that can be obtained from linking an ice-core tephra to its source, including eruption timing, plume height, tephra transportation distances, grain size and abundance. Knowledge of these characteristics is key for informing plume models which reconstruct past events where historic data is not available, and strengthen future hazard predictions. These findings demonstrate the opportunity the ice core volcanic records present to the wider volcanology community.