science

earthquake

earthquake

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

fault

A break in Earth's crust along which movement has occurred.

focus

Where an earthquake begins.

seismic wave

A vibration that travels through Earth carrying the energy released during an earthquake.

epicenter

Point on Earth's surface directly above an earthquake's focus.

elastic rebound

Tendency for deformed rock along a fault to spring back to its original shape after an earthquake.

aftershock

A small earthquake that follows the main earthquake.

p wave

Seismic wave that pushes/pulls rocks in direction of the wave.

s wave

A seismic wave that shakes particles perpendicular to the direction the wave is traveling.

surface wave

A seismic wave that travels along the surface of Earth.

seismograph

An instrument that records seismic waves.

seismogram

The record made by a seismograph.

moment magnitude

A more precise measure of earthquake magnitude than the Richter scale, which is derived from the amount of displacement that occurs along a fault zone and estimates the energy released by an earthquake.

liquefaction

The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud.

tsunami

The Japanese word for a seismic sea wave.

seismic gap

An area along a fault where there has not been any earthquake activity for a long period of time.

lithosphere

The rigid outer layer of Earth, including the crust and upper mantle.

asthenosphere

A weak plastic layer of the mantle situated below the lithosphere; the rock within this zone is easily deformed.

outer core

A layer beneath the mantle about 2260 kilometers thick; contains liquid iron and generates Earth's magnetic field.

inner core

The solid innermost layer of Earth, about 1220 kilometers in radius.

Moho

The boundary separating the crust from the mantle, discernible by an increase in the velocity of seismic waves.

continental drift

A hypothesis that originally proposed that the continents had once been joined to form a single supercontinent; The supercontinent broke into pieces, which drifted into their present-day positions.

sonar

Calculates ocean depth by recording the time it takes for an energy pulse to reach the ocean floor and return.

mid ocean ridge

A continuous elevated zone on the floor of all the major ocean basins and varying in width from 1000 to 4000 kilometers; The rifts at the crests of ridges represent divergent plate boundaries.

seafloor spreading

The process by which plate tectonics produces new oceanic lithosphere at ocean ridges.

subduction

The process by which oceanic crust sinks beneath a trench and back into the mantle at a colliding plate boundary.

paleomagnetism

The study of changes in Earth's magnetic field, as shown by patterns of magnetism in rocks that have formed over time.

plate

One of numerous rigid sections of the lithosphere that moves as a unit over the material of the asthenosphere.

plate tectonics

The theory that proposes that Earth's outer shell consists of individual plates that interact in various ways and thereby produce earthquakes, volcanoes, mountains, and the crust itself.

divergent boundary

A region where the rigid plates are moving apart.

convergent boundary

A boundary in which two plates move together.

transform fault boundary

A boundary in which two plates slide past each other without creating or destroying lithosphere.

continental volcanic arc

Mountains formed in part by volcanic activity caused by the subduction of oceanic lithosphere beneath a continent.

volcanic island arc

A chain of volcanic islands generally located a few hundred kilometers from a trench where subduction of one oceanic slab beneath another is occurring.

convection current

The motion of matter resulting from changes in temperature; specifically in the mantle; causes plates to drift.

slab pull

A mechanism that contributes to plate motion in which cool, dense oceanic crust sinks into the mantle and "pulls" the trailing lithosphere along.

ridge push

A mechanism that may contribute to plate motion; It involves the oceanic lithosphere sliding down the oceanic ridge under the pull of gravity.

mantle plume

A mass of hotter-than-normal mantle material that ascends toward the surface, where it may lead to igneous activity.

elastic, fault, energy

The ______ rebound hypothesis states that earth's internal forces act on both sides of a ______, causing the rock to deform and store ______, until eventually the strength of the rock is overcome and it snaps, releasing energy.

seismic

The earth serves as a medium for ______, body waves.

primary, fastest, pull, energy, refract, core, density

P (______) waves are the ______ traveling, function as "push-______", particles moving parallel to ______ (wave motion). They ______ (bend) when traveling through earth's ______ due to the increased ______ of the metal in this layer of the earth.

secondary, energy, outer, liquid

S (______) waves travel perpendicular to ______ (wave motion) and are completely blocked by the ______ core because they cannot travel through ______.

surface, circular, slowest, P, S

______ wave particles travel in a ______ pattern around the energy (wave motion). They are the ______ moving and can only travel on the surface. They are created by __ and __ waves combining on the surface.

seismograms, P, S, epicenter, 3

In order to locate an earthquake, one must first analyze ______ in order to determine the difference between __ and __ wave arrival times. You then plug this data into a time table chart which shows your distance from the ______. With __+ locations, we can pinpoint earthquake location.

rock

"Chemical composition" in regards to the layers of the earth can be summed up as ______ type.

oceanic

The crust is continental/______.

largest

The mantle is the ______ (size related) layer of earth.

iron, nickel

The core is primarily made of ______ and ______.

lithosphere

Which layer of earth contains the crust and upper mantle (tectonic plates)?

asthenosphere

Which layer of earth is easily deformed and is the location of convection currents?

lower

Which part of the mantle (lower or upper) is solid?

outer core

Which layer of the earth is liquid and creates Earth's magnetic field?

inner core

Which layer of the earth is solid due to immense pressure?

mechanical, chemical

The lithosphere and asthenosphere are defined based on ______ properties while the crust and mantle on ______ composition.

true

True or False; rocks can bend.

richter scale

Outdated unit of measuring earthquakes based on intensity.

c

How many major earthquakes happen per year? A: 1000; B: 150; C: 30,000; D: 1,000,000. Answer with letter.

true

True or False; it was not until the 1906 San Francisco earthquake that we began to study these natural disasters in depth.

iron

What generates the magnetic field in the outer core is a liquid layer of flaming metallic ______.

density

P waves bend when they enter into the outer core due to differences in ______.

landslide

A mass movement of soil.

oceanic crust

Made primarily of basaltic rock.

continental crust

Made primarily of granitic rock.

mantle

Similar to stony meteorites.

core

Similar to metallic meteorites.

Alfred Wegener

A German scientist who proposed the theory of continental drift

Pangea

Most recent supercontinent.

rock, glaciation, South America, Africa

Evidence for continental drift includes similar fossils, ______ type, and traces of ______ on separate continents: ______ ______ and southern ______.

Appalachian, Caledonian

The ______ mountains found in the US are similar to the ______ mountains found in Europe.

how

Wegener had one issue: he couldn't explain ______ (three letter word, starts with "H"). This resulted in him not being taken seriously.

rift valley

Central valley of mid ocean ridge.

outwards, 5

As new sea floor is added along mid ocean ridges, the older floor moves ______ at a rate of about __ cm per year.

stripes, earthquake

To support the idea of seafloor spreading, some proof includes magnetic ______ in ocean floor or rock, ______ patterns, and the age of ocean floor rocks.

paleomagnetism

When certain rocks form, they acquire the polarity that Earth's magnetic field has at the time, this is called what?

magnetic field

What causes grains in iron rich sea floor rock to orient to a certain direction (two word answer)?

deeper

Wadati and Benioff while studying earthquakes, found that the farther away from the trench the earthquakes were ______ into Earth's surface.

reverse polarity

A magnetic field opposite to that which exists at present.

true

True or False; deep-focus earthquakes occur away from ocean trenches within the slab of lithosphere descending into the mantle.

continents

The oldest oceanic crust is found near the edges of ______.

ridge crest

The youngest oceanic crust is found at the ______ ______.

divergent

Seafloor spreading begins at ______ boundaries.

convergent

Trenches, volcanoes, and mountain ranges can be produced from ______ boundaries.

oceanic, continental

______ lithosphere is more dense than ______ lithosphere.

transform

The San Andreas Fault is a ______ fault boundary.

false

True or False; divergent boundaries only occur on the ocean floor.