Earth's Interior

Question 1

Compression wave

Answer 1

A seimis wave that propagates by push-pull motion of a material.

Question 2

Conduction

Answer 2

The mechanical transfer of ehat energy by the mechanism of atomic or molecular impact.

Question 3

Convection

Answer 3

A mechanism of heat trasfer in which a heated expands and rises because it has become less dense that the surrounding material. Colder material flows in to take the place of hot rising fluid, is itself heated, and then rises to continue the cycle.

Question 4

Core-mantle boundary

Answer 4

The boundary between the core and lower mantle, about 2890km below surface, where S-wave speed drops from about 7.5 km/s to 0 and P wave from 13 km /s to 8km/s.

Question 5

Depositional remanent magnetism

Answer 5

A weak magnetization created in sedimentary rocks by the parallel alginment of magnetic particles in the directionof Earth’s magnetic field as they settle.

Question 6

Dipole

Answer 6

Two oppositely polarized magnetic poles.

Question 7

Geotherm

Answer 7

The curve that describes how temperative increases with depth in the Earth.

Question 8

Isostasy

Answer 8

The principle that the buoyancy force that pushes a lower-density body floating ina higher-density medium upward must be balanced by the gravitational force that pulls it downward.

Question 9

Low-velocity zone

Answer 9

A layer near the base of the lithosphere where the Swave speed abruptly decreases.

Question 10

Mohorovicic discontinuity

Answer 10

The boundary between the crust and the mantle at a depth of 5 to 45 km marked by an abrupt increase in Pwave velocity to more than 8km/s.

Question 10

Paleomagnetism

Answer 10

The remanent magnetization recoded in ancient rocks, which allows the reconstruction of Earth’s ancient magnetic field and the positiions of continents and supercontinents.

Question 11

Phase change

Answer 11

A transtiion in a rock’s mineralogy to a denser, more closely packed crystal structure, signaled by a chnage in seismic-wave velocity.

Question 12

Seismic tomography

Answer 12

A method that uses the seimic waves from earthquakes recorded on thousands of seismographs all over the world to sweep Earth’s interior in many different directions and construct a 3D image of what’s inside.

Question 13

Shadow zone

Answer 13

(1) A zone beyond 105 degrees from the focus of an earthquake where S waves are absent because the waves are not transmitted through the liquid outer core. (2) A zone at an angular distance of 105 to 142 degrees from the focus of an earthquake where P waves are absent because they are refracted downward into the core and emerge at greater distances after the delay cause by their detour through the core.

Question 14

Shear wave

Answer 14

A wave that propagates by a side-to-side motion. Shear waves cannot propagate through any fluid–air, water, or liquid iron in Earth’s outer core..

Question 15

Thermoremanent magnetization

Answer 15

A permanent magnetization acquired by minerals in igneous rocks when groups of atoms of the mineral align themselves in the direction of the magnetic field that existed when the material was hot. When the material has cooled, these atoms are locked in place and therefore are always magnetized in the same direction.