Keywords 3.2

Chile trembles

Aftershocks

Smaller earthquakes that happen after a big one, in the same area.

Block mountain ranges

Mountains formed when land between faults rises or sinks (horsts and grabens).

Continental plate

A thick, solid part of Earth's crust that forms landmasses.

Convergence

When two tectonic plates move toward each other and collide.

Divergence

When two tectonic plates move away from each other.

Epicentre

The point on the Earth's surface directly above where an earthquake starts.

Fault

A crack in the Earth's crust where movement happens during earthquakes.

Fold mountain range

Mountains formed when rocks are pushed up by the collision of plates.

Hypocentre

The place inside the Earth where the earthquake actually starts.

Magma

Molten (melted) rock beneath the Earth's surface.

Normal fault

A crack where one block of rock slides down compared to the other—happens in divergent zones.

Oceanic plate

A thinner tectonic plate under the ocean, denser than continental plates.

Relief

The shape and height differences in a landscape, like hills and mountains.

Reverse fault

A fault where one block of rock is pushed up over another—happens in convergence zones.

Richter scale

A scale that measures how strong an earthquake is.

Seismic gap

A part of a fault that hasn't had an earthquake in a long time and may break soon.

Strike-slip fault

A fault where two blocks of rock slide past each other horizontally.

Subduction

When one tectonic plate slides under another into the mantle.

Transform movement

When two tectonic plates slide past each other.

Trench

A deep underwater valley formed at a subduction zone.

Tsunami

A huge wave caused by an underwater earthquake or volcanic eruption.