No abstract

No abstract

No abstract

[1] Throughout February and March of 1997 Okmok Volcano, in the eastern Aleutian Islands of Alaska, erupted a 6 km long lava flow of basaltic 'a'a within its caldera. A numerical model for lava flow cooling was developed and applied to the flow to better understand the nature of its cooling. Radiation and convection from the surface, as well as conduction to the ground, were used to transport the flow's heat to its surroundings in the model. Internally, a conduction-only approach moved heat from the interior outward. Vesiculation, latent heat generation, and thermal conductivity changes with temperature are among the other factors that were dynamically accounted for. Results indicate that ambient temperature fluctuations, on the scale of days to weeks, must be taken into account to create an accurate short-term prediction of lava surface temperature. Daily data of rainfall and ambient temperature, as opposed to yearly averages, greatly increased the accuracy of the model. Furthermore, convective cooling of the lava surface was observed to be a dominant heat loss process during the first 200 days, indicating the convective heat transfer coefficient is a prime determinant of the accuracy of the model for predicting surface temperatures. Over a longer cooling period (2 years), thermal conductivity and porosity proved to be among the dominating factors for heat loss because of the limiting role of conductive heat flow in the interior. The model's flexibility allows application to flows other than the 1997 Okmok eruption.