Thermal analysis using TGA-DSC and TMA. (a) Fixed-rate TGA showing thermally induced mass loss for the surficial and subsurface hyaloclastites. (b) Fixed-rate DSC showing low-temperature heat capacity peaks against temperature for surficial samples and high-temperature peaks for subsurface samples. (c) TGA showing mass loss during the sequential 12-hour isothermal dwells, for surficial hyaloclastite. (d) Fixed-rate TMA for the surficial and subsurface samples, showing volumetric collapse for surficial material and a range of depth-dependent responses for subsurface material.