Plate Tectonics and Seismic Waves

seismic waves

vibrations that travel through Earth carrying the energy released during an earthquake

inner core

A dense sphere of solid iron and nickel at the center of Earth

outer core

A layer of molten iron and nickel that surrounds the inner core of Earth

crust

The thin and solid outermost layer of the Earth above the mantle

radioactive elements

unstable elements that decay or break down into different elements

convection currents

Circular currents in the mantle caused by the magma being heated by the core off the Earth.

planetary differentiation

This is a process in which more dense materials of a planet sink to the center, while less dense materials stay on the surface.

igneous rock

a type of rock that forms from the cooling of molten rock at or below the surface

magma

A molten mixture of rock-forming substances, gases, and water from the mantle

tectonic plates

a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle

paleomagnetism

The study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock requires during formation

continental drift

The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations

sea-floor spreading

The process by which molten material adds new oceanic crust (lithosphere) to the ocean floor

divergent boundary

A plate boundary where two plates move away from each other.

convergent boundary

A plate boundary where two plates move toward each other.

transform boundary

A plate boundary where two plates move past each other in opposite directions

subduction zone

The region where oceanic plates sink down into the asthenosphere.

Wegener

proposed the theory of continental drift

Hess

Proposed sea floor spreading

faults

Breaks in Earth's crust where rocks have slipped past each other.

island arc

A string of islands formed by the volcanoes along a deep ocean trench

hot spot

An area where magma from deep within the mantle melts through the crust above it

rift valley

A deep valley that forms where two plates move apart

earthquake

The shaking that results from the movement of rock beneath Earth's surface.

tsunami

A giant wave usually caused by an earthquake beneath the ocean floor.

Primary Waves (P-Waves)

Travel the fastest through rock material by causing particles in the rock to move back and forth , or vibrate, in the same direction as the waves are moving.

Secondary Waves (S Waves)

type of seismic body waves that are Slower and ONLY travel through SOLIDS.

Seismometer (Seismograph)

an instrument that can record the ground motion from an earthquake

density

Mass per unit volume

Lithosphere

A rigid layer made up of the uppermost part of the mantle and the crust.

Asthenosphere

The soft layer of the mantle on which the lithosphere floats.

Epicenter

the point on the Earth's surface directly above the focus of an earthquake