Compaction of Hyaloclastite from the Active Geothermal System at Krafla Volcano, Iceland
Physical and mechanical attributes of hyaloclastites from different depths within the hydrothermal reservoir at Krafla volcano, NE Iceland. (a) Permeability (at an effective pressure of 4 MPa) as a function of porosity showing a nonlinear positive correlation. (b) Strength as a function of porosity showing a nonlinear negative correlation. (c) Young’s modulus decreases by an order of magnitude over the range of porosity examined. (d) Critical effective mean stress (critical ), marking the brittle to ductile transition of each material depends on porosity (note the value for the sample from 556 m is a minimum as critical was not met up to an effective mean stress of 75 MPa).