Question

Will an effusive eruption have more gas and be more dense (viscous) than an explosive flow, or will it be less gaseous and less viscous?

Answer 1

Effusive eruptions involve the outpouring of basaltic magma that is relatively low in viscosity and in gas content. Explosive eruptions generally involve magma that is more viscous and has a higher gas content. Such magma is often shattered into pyroclastic fragments by explosive gas expansion during an eruption.