Constraints on the rates of degassing and convection in basaltic open‐vent volcanoes

摘要: Variations in gas emissions of open-vent volcanoes are investigated using a model magma convection narrow conduits. Laboratory experiments with both vertical and inclined conduits dimensional analysis show that for Grashof numbers lower than 100 the volumetric rate ascent is simple function equivalent conduit radius, density difference between magmas, viscosity degassed descends back to reservoir. The depends on flux coefficient, estimated as 0.1 0.2 conduits, respectively. radius parameter accounts dimensions conduit(s) regardless its geometry, thus extending treatment by previous models used flow pipes. volume increases higher size, but also highly influenced large variations volatile content crystallinity change. presented here can be constrain degassing rates volatile-rich when combined petrologic data magmatic content. Application Villarrica volcano (Chile) reveals background levels observed (∼3 kg s−1 SO2) associated convective relatively (0.04 wt% S, ∼0.5 H2O), while episodes SO2 (measurements up 15 s−1) explained (up 0.09 ∼1.5 H2O).