Plate Tectonics and Geologic Activities - Vocabulary

A set of vocabulary flashcards covering key terms and definitions in Plate Tectonics and related geologic activities.

Lithosphere

The rigid outer layer of Earth, comprising the crust and the upper mantle; it is divided into tectonic plates.

Asthenosphere

The weak, partially molten zone of the upper mantle that behaves plastically and allows plate movement.

Tectonic plates

Huge slabs of rock that make up Earth's lithosphere; move slowly due to mantle convection and include both oceanic and continental crust.

Oceanic crust

Crust made primarily of basalt; thinner and more dense than continental crust.

Continental crust

Crust made mainly of granitic rocks; thicker and less dense than oceanic crust.

Major tectonic plates

The seven largest plates, e.g., Pacific, North American, Eurasian, African, Antarctic, Indian-Australian, and South American.

Minor tectonic plates

Smaller plates such as Caribbean, Nazca, Cocos, Somali, Philippine Sea, Arabian, Caroline, Scotia, and Burma plates.

Plate boundaries

Edges where tectonic plates interact, including zones of collision, subduction, or sliding past one another.

Subduction

Process by which a denser plate sinks beneath a less dense plate at a convergent boundary, often forming trenches and volcanoes.

Trenches

Long, narrow depressions at subduction zones where one plate sinks beneath another.

Volcanoes

Vents in the Earth's crust where magma erupts; commonly form at plate boundaries, especially subduction zones.

Earthquakes

Ground shaking caused by the movement of tectonic plates at boundaries or faults.

Mountain belts

Long, thickened regions of rock formed by plate collisions or subduction and associated deformation.

Plate tectonics theory

The lithosphere is divided into moving plates that interact at boundaries, driven by mantle convection, producing earthquakes, volcanoes, and mountains.

Mantle convection

Heat-driven circulation in the mantle that enables tectonic plates to move.

P-waves (Primary waves)

Body seismic waves that compress and expand, travel through both solids and liquids, and arrive first at seismic stations.

S-waves (Secondary waves)

Body seismic waves that move the ground perpendicular to the direction of travel; can travel only through solids and arrive after P-waves.

Surface waves

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

Epicenter

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

Focus (hypocenter)

The point within Earth where an earthquake starts or originates.

Triangulation method

A method to locate an earthquake’s epicenter using the intersections of distance circles from at least three seismic stations.

Time difference (P–S arrival)

The interval between the arrival of P-waves and S-waves at a seismic station, used to estimate distance to the epicenter.

Acasta Gneiss

Oldest known continental crust fragment, dated at about 4.01 billion years ago using Zircon dating.

Mediterranean Sea seafloor age

Oldest oceanic crust seafloor dated at about 340 million years ago.

Philippine Sea Plate

A major tectonic plate located near the Philippines; interacts with surrounding plates and contributes to regional seismic and volcanic activity.

Eurasian Plate

A major tectonic plate that interacts with neighboring plates at plate boundaries.

Pacific Plate

A major tectonic plate that moves relative to surrounding plates and forms many subduction zones and trenches.

North American Plate

A major tectonic plate whose boundaries interact to produce earthquakes and volcanism in nearby regions.

African Plate

A major tectonic plate contributing to Africa's tectonic activity and adjacent ocean basins.

Nazca Plate

A minor plate located off the west coast of South America, subducting under the South American Plate.

Caribbean Plate

A minor plate located in the Caribbean region with tectonic activity at its boundaries.

Cocos Plate

A minor plate subducting beneath the Central American and Mexican regions, creating regional volcanism and earthquakes.

Somali Plate

A minor plate in the eastern African region interacting with surrounding plates.

Arabian Plate

A minor plate in the Middle East region interacting with adjacent plates.

Caroline Plate

A minor plate in the western Pacific region contributing to complex plate interactions.

Scotia Plate

A minor plate in the South Atlantic with interactions at its margins.