Which mechanism dictates volcanic eruption explosivity when magma's silica content rises above approximately 65%?

💡 Explanation

When silica content exceeds ~65%, increased polymerization occurs because silica tetrahedra link together more extensively, dramatically increasing magma viscosity and impeding gas escape, raising eruption's explosive potential. Therefore, higher magma density and viscosity results, rather than changing nucleation, crystallization or mineral precipitation, where these relate to alternative factors.

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