Magma traps composed of such cracks may grow into magma reservoirs if the production rate of cracks in the mantle is large. For the hydrostatic stress conditions, most magma-filled cracks beneath a polygenetic volcano become trapped either in the lower crust, because there the density difference between magma and the host rocks (Δρ) becomes suddenly small, compared with that in the mantle, or trapped in the upper crust, because there Δρ is near to zero. Numerical solutions of crack propagation for various stress conditions, with a constant production rate high enough to coalesce isolated cracks, were performed, and the results applied to different tectonic conditions. The system is controlled by two boundary conditions: the stress field, and the production rate of the magma-filled cracks in the mantle. This paper considers only a basaltic magma.
A system of propagating cracks may explain magma transport and the evolution of a volcano.
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