Explosiveness of an Eruption

Low

High

Runny

Travels Faster

Shield Volcanoes

Thick

Travels Slower

Composite Volcanooes

Less Silica

<50% Silica = Basaltic Magma

Low Gas > Effusive Content

Hotter

More Silica

70% > *Rhyolitc Lava

Traps Gas Bubbles > Explosive

Cooler

Sometimes blocks vent > Pressure > More explosive

Magma = Silica + Oxygen > Viscosity

Medium Sized Eruptions

60% Silica = Andesite