Plate Tectonics and Tectonic Hazards Lecture Review

This set of vocabulary flashcards covers the structure of the Earth, plate tectonics, internal geological processes, landform formation at various plate boundaries, and the causes and management of tectonic hazards.

Continental crust

A layer of the earth 25–70 km thick, made mainly of silica with more aluminium, potassium, and sodium; it is thicker, lighter, and consists of relatively old rock.

Oceanic crust

A layer of the earth 6–8 km thick, found under oceans, made mainly of silica with more iron and magnesium; it is thinner, denser, and consists of relatively young rock.

Mantle convection

A mechanism of heat transfer where rock in the lower mantle is heated by the core, rises as mantle plumes, cools at the surface, and sinks back down.

Ridge push

A force driving plate movement where new oceanic lithosphere cools, increases in density, and slides down from the sides of a ridge under gravity.

Slab pull

A suction force created when a dense, heavy slab of plate sinks into the asthenosphere, pulling the rest of the plate behind it.

Folding

The process by which rock layers are folded up under compressional force, forming landforms like fold mountains.

Faulting

The displacement of rocks along cracks or fractures called faults, occurring when stress exceeds the internal strength of the rock.

Normal fault

A type of fault formed under tensional force where the hanging wall block moves down.

Reverse fault

A type of fault formed under compressional force where the hanging wall block moves up.

Strike-slip fault

A type of fault formed under shearing force where rock blocks slide past each other horizontally.

Block mountain (horst)

A landform with steep fault scarps and a flat top, formed when tensional or compressional forces cause vertical displacement of land blocks.

Rift valley (graben)

A large-scale landform, such as the East African Rift, formed when the central block between faults sinks.

Extrusive volcanism

Volcanic activity where magma reaches the earth's surface and becomes lava, forming volcanoes, craters, and lava plateaus.

Intrusive volcanism

The process where magma cools and solidifies before reaching the earth’s surface, forming features like batholiths, sills, and dykes.

Caldera

A large depression at the top of a volcano formed when the summit collapses into the magma chamber.

Batholith

A large mass of intrusive rock formed deep underground.

Mid-oceanic ridge

A submarine ridge formed at a divergent plate boundary where rising magma cools and solidifies to create new crustal material.

Subduction

The process at convergent boundaries where a denser plate slides below a less dense plate and sinks into the asthenosphere.

Ocean trench

A deep and elongated trough under the sea formed at a subduction zone, such as the Peru-Chile Trench or Java Trench.

Volcanic island arc

A chain of volcanic islands, like Indonesia, formed by volcanic eruptions on the ocean floor parallel to an ocean trench during ocean-ocean collision.

Focus

The point beneath the earth's surface where an earthquake occurs and energy is first released.

Epicentre

The point on the earth's surface directly above the earthquake focus, where the strongest ground shaking usually occurs.

Pacific Ring of Fire

A line of active volcanoes and frequent seismic activity that roughly surrounds the Pacific Ocean.

Hot spot

A place away from plate boundaries where a mantle plume rises from the core-mantle boundary, creating volcanoes or volcanic island chains like the Hawaiian Islands.

Tsunami

A series of big sea waves traveling at speeds of $700\,\text{km/h}$ or more, generated by submarine earthquakes, volcanic eruptions, or landslides.

Primary effects (Earthquakes)

Immediate destruction including damaged structures (buildings, bridges), injuries, deaths, and broken water, power, or gas pipes.

Secondary effects (Earthquakes)

Consequential impacts such as fires, landslides, tsunamis, flooding from dam collapses, and the spread of diseases.

Lava diversion channel

A mitigation structure built to divert lava flow away from densely populated areas to minimize casualties and losses.

Geothermal power

Energy generated by hot water and steam found in volcanic areas, providing job and business opportunities.

San Andreas Fault

A typical example of a transform plate boundary located between the North American Plate and the Pacific Plate.