Rock Fractures and Fluid Flow
Research topics and projects include:
Rock fractures of any type, including those associated with rifting episodes, joints and fault formation, caldera collapses, landslides, and dyke-fed volcanic eruptions, all depend on fracture propagation, commonly through many layers. The material toughness of a volcanic edifice, a seismic zone, and a rock mass is related to the energy absorbed by the material as it fractures. Much of fracture mechanics has been developed for homogeneous, isotropic materials, but for a full application to geological and geophysical problems, one has to extend the principles of fracture mechanics to heterogeneous and anisotropic materials, in particular to layered rock masses.
Currently, we are exploring the implications of the basic idea that rock masses composed of similar layers have less material toughness (resistance to fracture propagation) and are thus more easily fractured than masses composed of layers with widely different properties and contacts, such as typical in stratovolcanoes but also in sedimentary basins with numerous sill intrusions. In other words, propagating fractures tend to be more easily arrested in rock masses composed of layers with different properties (particularly Young’s moduli) than masses composed of layers with similar properties.
Thus, for example, one might expect landslides, caldera collapses, and dyke-fed eruptions to occur with much greater ease in basaltic edifices than in stratovolcanoes, which seems to be the case. I have already published some papers on this topic (cited) but much more work needs to be done – using a combination of field studies and analytical, experimental (analogue), and numerical modelling.
| Fracture propogation scenarios
|| Internal structure of volcanoes