Thermal property measurements in a fresh pumice flow at Mt. St. Helens

Abstract

A thermal penetrator that was air dropped into a freshly emplaced pumice flow at Mt. St. Helens yielded information on the in‐situ thermal properties of the pumice. The in‐situ conductivity‐density‐specific heat product at a depth of 60 cm was found to be 7.24 × 10−5 cal²/cm4s−°C² at an average pumice temperature of 200°C. Using this data, values for the average in‐situ thermal conductivity (2.9 × 10−4 cal/cm−s−°C) and thermal diffusivity (1.2 × 10−3 cm²/s) were estimated. These thermal properties are of use in studies of pumice cooling and in the interpretation of infrared remote sensing data.