Inclination and heterogeneity of layered geological sequences influence dike-induced ground deformation

Constraints on the amount and pattern of ground deformation induced by dike emplace-ment are important for assessing potential eruptions. The vast majority of ground deforma-tion inversions made for volcano monitoring during volcanic unrest assume that dikes are emplaced in either an elastic half-space (a homogeneous crust) or a crust made of horizontal layers with different mechanical properties. We extend these models by designing a novel set of two-dimensional finite-element method numerical simulations that consider dike-induced surface deformation related to a mechanically heterogeneous crust with inclined layers, thus modeling a common geometry in stratovolcanoes and crustal segments that have been folded by tectonic forces. Our results confirm that layer inclination can produce localized ground deformation that may be as much as 40x higher in terms of deformation magnitude than would be expected in a non-layered model, depending on the angle of inclination and the stiffness of the rock units that host and are adjacent to the dike. Generated asymmetrical deformation patterns produce deformation peaks located as much as 1.4 km away from those expected in non-layered models. These results highlight the necessity of accurately quantify-ing both the mechanical properties and attitude of the geology underlying active volcanoes.

Automated summary

Considering the impact of inclined layers in the crust on ground deformation is crucial for assessing potential volcanic eruptions. Our numerical simulations show that inclined layers can result in localized ground deformation that is up to 40 times higher in magnitude compared to non-layered models. These findings highlight the importance of accurately characterizing the mechanical properties and orientation of the geological layers beneath active volcanoes.