부산대학교 도서관

Most large ocean-island volcanoes are gravitationally unstable. Some deform slowly, forming long-lived slumps, while others collapse and generate potentially dangerous debris avalanches. Here we investigate the effect of pervasive dyke networks on edifice instability, using data from La Palma, Spain. Like fibre-reinforced composites, where rigid layers are embedded in a compliant matrix, we find that dykes experience higher stress than surrounding host rocks. If the ratio of dyke to host stiffness is larger than the corresponding strength ratio, the dyke network will fail first, causing a rapid stress redistribution and possibly triggering edifice collapse. Fibre bundle models of a weak layer crosscut by dykes suggest this can occur with less seismicity or deformation than models without dykes. The models also suggest that dyke network strength could determine the potential for rapid collapse rather than gradual slump-type deformation. We conclude that dyke networks should be considered when assessing volcanic edifice stability.
Catastrophic collapses of volcanic edifices could be triggered by the failure of a few highly interconnected dikes and rapid redistribution of stresses into weak layers, according to micromechanical models informed by field data at Caldera Taburiente, La Palma.