The influence of graben geometry on dike propagation

Abstract

Understanding dike behavior under varying topographical stresses is essential for predicting volcanic vent locations. This study addresses how graben geometry influences dike propagation by employing an experimental approach to simulate dike propagation, using fluids as analogs for magmas. We inject these fluids into the center of the base of an elastic gelatin medium, molded with an elongated topographic low representing a graben structure in the Earth's crust. Experiments involving different graben geometries were conducted to assess how local stress fields influence dike propagation. The results demonstrate that shallow grabens facilitate vertical to sub-vertical dike propagation within the graben, while deeper grabens cause dike deflection, often leading to off-graben venting or the formation of canoe-like sheet intrusions. These findings introduce new variables into the understanding of volcanic vent locations and eruption forecasts, particularly in rift zones with complex topography. The results offer critical implications for improving volcanic hazard assessments by incorporating the influence of topographical stress on dike propagation. Overall, the study advances our understanding of the mechanisms controlling dike propagation and provides a basis for further research into mitigating risks associated with volcanic eruptions in a graben setting.