Tectonic Plates and Volcanic Activity

Vocabulary terms covering plate tectonics, constructive and subduction boundaries, volcanic hazards, monitoring techniques, activity states, and reasons human settlements remain in hazardous volcanic zones.

Convection Currents

Circulating currents in the mantle that drag against the underside of the crust to move tectonic plates.

Ridge Push

A process where the weight of the mid-ocean ridge sitting higher than the rest of the plate pushes the plates apart, causing them to move faster than convection currents.

Subducting Plate

A heavier tectonic plate that is forced down below a lighter plate into the mantle where it melts, allowing molten rock to rise to the surface through cracks in the rocks and create an eruption.

Constructive Plate Boundary

A boundary where two plates move away from each other and magma rises through the gap, cooling to form new crust and creating an underwater mountain over time.

Pyroclastic Flows

Fast-moving, highly dangerous clouds of extremely hot gas, ash, and volcanic rock that rush down the sides of a volcano during an eruption.

Primary Hazards

Immediate hazards directly caused by a volcanic eruption, specifically lava flows, ash fall, pyroclastic flows, and volcanic bombs.

Secondary Hazards

Hazards resulting from the aftermath of volcanic activity, specifically lahars, landslides, flooding, and crop failure.

Volcano Monitoring and Prediction

Methods used to assess volcanic activity, including gas measurements, temperature changes, ground deformation, and detecting magma underground.

Active Volcano

A volcano with regular eruptions and an active magma system that is likely to erupt in the future.

Dormant Volcano

A volcano that has not erupted in a long time, but where activity can still be detected.

Extinct Volcano

A volcano that will not erupt again and where no activity can be detected.

Mt Pinatubo Tribe

An example of communities choosing to stay in hazardous volcanic areas because their families have lived there for generations and do not want to leave.

Volcanic Soil

Fertile soil created by volcanic activity that attracts farming and employment to hazardous areas.

Geothermal Energy

A resource provided in volcanic zones that serves as a reason people stay in hazardous areas by offering cheap electricity.