The overall aim of the project is to understand the preservation of airborne volcanic ash (tephra) from small- and medium-scale eruptions. Tephra from eruptions of this scale can be disproportionately disruptive to aviation (e.g., the Eyjafjallajökull eruption in 2010 led to the cancellation of >100,000 flights), so it is important to understand how often it enters UK airspace and the areas it can affect. The observational record is short (in geological terms,) but the frequency and extent of tephra deposition can be inferred from sedimentary records. Small- to medium-scale eruptions like Eyjafjallajökull in 2010 are common; furthermore, studies of tephra deposits invisible to the naked eye (cryptotephras) have revealed that fine tephra shards can be transported over continental-scale distances. Given this, the UK sedimentary record should be packed with tephra from small- to medium scale Icelandic eruptions. However, this is not the case, indicating that we could be underestimating the incursion of volcanic ash into UK airspace. The sparsity of tephra from small- to medium-scale eruptions could be because there is a minimum intensity of fallout below which preservation is unreliable; alternatively, it could be due to variability in preservation (taphonomy) among different environments (e.g., lakes and peatlands) or a consequence of under-sampling. This project will focus on locations in the UK where tephra fallout has been recorded, in order to understand how that tephra was preserved in the sedimentary record (or not).
The project addresses three main challenges:
Component 1: We need to understand if there is a minimum threshold for the preservation of cryptotephras so we can assess the visibility of small- to medium-scale Icelandic eruptions in the UK sedimentary record.
Component 2: We need to understand the extent to which taphonomic processes in different environments might produce very different crypotephra records from the same initial deposit.
Component 3: We need to understand how cryptotephra deposits vary within individual lakes, in order to optimise sampling strategies.