18.1 Notes: Hawaiian – Type Volcano

18.1 Notes:

Hawaiian – Type Volcano

Describe:Weakest eruption; lava travels very slowly & far

Fissure EruptionDescribe:

When lava is released through surface fissures (cracks) instead of out of the central vent of a volcano.

Low-Viscosity Magma

Describe:The eruption is weak & can travel long distances

because pressure doesn’t build

High-Viscosity MagmaDescribe:

Pressure builds because the magma is not able to flow fast. This can produce violent eruptions.

Eruption Types

StrombolianDescribe:

Short explosions that shoot out a small amount of very thick lava, often producing cinder cones

Types of High-Viscosity Eruptions

VulcanianDescribe:

Small, Violent plumes of steam, ash, & gas up to 16km. Magma is thick, pasty, filled w/ gas.

Intermittent explosions as gas released. Often forms cinder cones.

PeleanDescribe:

Key components: glowing avalanche of hot gases, ash, & rock pour down at speeds greater than 160km/h.

Common for composite cone volcanoes.

PlinianDescribe:

Largest & most violent explosive eruptions large ejections of pumice & ash that can reach heights of

50km & spread to large areas downwind. Can affect weather!

MT St Helens for example