Property

Basaltic (mafic)

Andesitic (intermediate)

Rhyolitic (silicic)

Example

Hawaii, Iceland

Mt. St. Helens, Mt. Pinatubo

Yellowstone, Mammoth Lakes (CA)

Typical (but not only!) tectonic environment

mid-ocean ridges, oceanic hotspots, intracontinental extension

Above subduction zones

continental hotspots, intracontinental extension

Eruptive temperature

hottest

intermediate

coolest

Silica (SiO₂) content

Least (~50%)

Intermediate (~60%)

Greatest (70%-75%)

Water and other gases

least

intermediate

most

Viscosity

lowest (very fluid)

intermediate

greatest (stiffest)

Products

mostly flows

flows and tephra

mostly tephra

Volcano form

shield volcano, rifts; cinder cones

stratovolcano

domes, large calderas

Eruptive types, products, and sources

lava flows, tephra, gases

lahars, tephra, pyroclastic flows, ash falls, lava flows

gas, tephra, pyroclastic flows, lahars, ash falls, lateral blasts, some lava flows, lava domes