Unit 3: Breaking and Building the Lithosphere Vocabulary

A set of 50 vocabulary flashcards covering key concepts related to earthquakes and volcanoes.

Plate tectonics

The theory that the Earth's rigid outer layer is broken into solid slabs (tectonic plates) that move relative to one another.

Fault

A fracture in the Earth's crust where two blocks slip past each other, causing earthquakes.

Seismic waves

Vibrations that travel outward from an earthquake fault, shaking the ground.

Focus (hypocenter)

The location within the Earth's crust where an earthquake rupture begins.

Epicenter

The point on the Earth's surface directly above the earthquake focus.

Magnitude

The amount of energy released during an earthquake.

Richter scale

A logarithmic scale for measuring earthquake magnitude, indicating wave amplitude.

Moment Magnitude Scale (MMS)

The preferred scale for measuring earthquake magnitude, especially for large quakes.

Seismograph

An instrument that detects and records seismic waves.

Seismogram

The visual record produced by a seismograph showing ground motion over time.

Foreshocks

Smaller earthquakes that precede a larger main earthquake.

Mainshock

The largest primary earthquake in a sequence.

Aftershocks

Smaller earthquakes that follow the mainshock and occur in the same area.

Liquefaction

When water-saturated sediment behaves like a liquid during intense ground shaking.

Landslide

A mass movement of earth triggered by earthquakes, causing extensive destruction.

Tsunami

A large ocean wave caused by the displacement of water, often from undersea earthquakes.

Body waves

Seismic waves that travel through the Earth's interior.

P-waves (Primary waves)

The fastest seismic waves that are compressional and move material back and forth.

S-waves (Secondary waves)

Slower seismic waves that move the ground side to side or up and down.

Surface waves

Seismic waves that travel along the Earth's surface and cause the most damage.

Magma

Molten rock located beneath the Earth's surface.

Magma chamber

An underground reservoir where magma collects before an eruption.

Lava

Molten rock that has erupted and flows onto the Earth's surface.

Vent

The opening at the Earth's surface through which volcanic materials erupt.

Conduit

The pipe-like channel that brings magma from the magma chamber to the vent.

Crater

A circular depression surrounding the vent at the top of a volcano.

Caldera

A large crater formed by the collapse of a volcano following a violent eruption, often filled with water.

Convergent plate boundary

Where two tectonic plates collide, leading to volcanic activity.

Divergent plate boundary

Where tectonic plates pull apart, allowing magma to rise and create new crust.

Hot spot

Area of volcanic activity located away from plate boundaries, often resulting in an island chain.

Eruption

The release of volcanic materials like lava and gas from a vent.

Viscosity

The thickness or stickiness of magma, affecting eruption style.

Effusive eruption

A non-explosive eruption that produces lava flows and domes.

Explosive eruption

A violent eruption that ejects ash and gas high into the air.

Pyroclastic flow

A fast-moving mixture of volcanic gas, ash, and rock fragments during an explosive eruption.

Shield volcano

A large, gently sloping volcano formed by low-viscosity lava flows.

Composite volcano (Stratovolcano)

A tall, steep-sided cone formed from alternating layers of lava and ash.

Cinder cone

The smallest type of volcano, formed from the accumulation of rocky fragments around a vent.

Volcanic hazards

Potential dangers associated with volcanic eruptions.

Lahar

A destructive volcanic mudflow made from a mixture of water and volcanic debris.

Vog (Volcanic smog)

A hazy mixture of sulfur dioxide and aerosols from volcanic gases.

Normal fault

A type of fault where the hanging wall moves downward relative to the footwall, typically caused by extensional forces.

Reverse Fault

A type of fault where the hanging wall moves upward relative to the footwall, typically caused by compressional forces.

Strike-slip fault