Abstract
The convective flow in a buried caldera was calculated by numerical simulation, and it was found that the upflowing hot water above the slope of the caldera basement could be generated as the convection mode of an isothermal basement model.
Temperature data from well loggings in the Hohi geothermal area indicate upflowing hot water above the slope of the basement.
The numerical simulation of the flow in Shishimuta caldera at the Hohi area reveals that the collision of downflowing cold water from the caldera rim and the upflowing hot water above the hot basement surface creates the upflow perpendicular to the basement surface.
The convective patterns for both an isothermal basement model and an uniform heat flow model were compared. The results are different. The calculated temperature of the uniform heat flow model shows some discrepancies with log data.
The effects of a local heat source on the basement and a horizontal impermeable layer in the upper part of the convection cell were examined, and they were found to influence the location and the shape of the upflow region. The effect of an impermeable layer is significant in case of the deeper heat source beneath the caldera.
