Volcanoes

Can erupt both violently and gently

Cause violent eruptions

Pillow lava is usually found at

Granitic magma containing volcanoes are more likely to be found at divergent plate boundaries.

can reach great heights disrupting air traffic and air quality

Magma forms deep inside Earth due to

As pahoehoe lava cools it forms a rope-like structure

low silica content

Ash and droplets reflect sunlight into space causing a decreased temperature on Earth.

This volcanic eruption most likely occurred

Silica causes magma to be viscous (or thick).

Number of potentially active volcanoes on Earth

In 1963, the new island of ___ was formed during an eruption.

It is more difficult for bubbles to escape high-viscosity magma creating a violent eruption.

Iceland sits on this

eruptions are gentle

Acid rain forms when ___ mixes with water vapor in the air.

determines if a volcanic eruption will be violent or gentle

Magma is less dense than the rock around it so it is forced up toward Earth's surface.

At lower temperatures lava is stiff, slow moving and referred to as ___.