COOLING RATES OF SPATTER DEPOSITS

Volcanic spatter occurs when erupted lava is hot enough to deform and agglutinate (adhere to other erupted clasts). The deformation and agglutination of spatter clasts have not yet been fully quantified, yet they have important implications regarding the flow regime of these deposits. Spatter deposits will agglutinate at high temperatures; however, if the temperature is too high it will re-mobilize and flow as lava. It is important to understand the accumulation and cooling conditions that lead to the remobilization and collapse of spatter as these events can present a serious volcanic hazard.

A two-dimensional thermal diffusion model has been created in this study. This model predicts how spatter clasts cool over time when subjected to conduction, convection, and radiation. This model is applied to scenarios in which multiple spatter clasts of the same temperature are placed on top of one another. We varied the clast thickness, number of clasts deposited, and the accumulation rate to determine the primary controls on spatter cooling rates.

The model described in this research provides an indication for when the spatter deposit will cool to the glass transition temperature. Multiple scenarios, including differing amounts of spatter clasts and differing timescales between clast deposition have been applied to this model. This research allows for a better understanding of the controls on the cooling rates of the clasts as well as the transition into the clastogenic flow regime, which will increase understanding of volcanic spatter as well as have implications for the mitigation of their associated hazards.