Earthquakes: Glossary

A

aftershock

a smaller earthquake following the original

C

convergent boundary

boundary where two plates are moving toward each other

core

central part of the earth made of iron and nickel

crust

outer solid portion of the earth from 5 - 30 miles deep

D

divergent boundary

boundary between two plates that are moving apart

E

earthquake

sudden, rapid shaking of the earth's crust caused by moving tectonic plates

epicenter

a location on the earth's surface directly above the earthquake's focus

F

fault

the place where tectonic plates meet or come together

foci

plural form of the word focus

focus

a location inside the earth where the earthquake takes place

G

geologist

scientist who studies the earth

H

hazard

danger

hypocenter

The point within the earth where an earthquake rupture begins, also known as the focus

I

intensity

strength

L

liquefaction

during an earthquake, solid surfaces can react like liquids

M

Mercalli Intensity Scale

a method of measuring earthquakes based on visual observation - uses a scale of 1-12

magnitude

the amount of energy released from an earthquake

mantle

the melted layer of the earth just below the crust

P

P waves

primary or first waves of an earthquake that move longitudinally

plate margin

the area where two tectonic plates meet

R

Richter Scale

a method of measuring earthquakes based on seismographic readings

Ring of Fire

an active zone around the pacific ocean where plates of oceanic crust slip under the continental crusts - 4 out of 5 earthquakes take place along the pacific ring of fire - a huge number of volcanoes lie in the area too

S

S waves

secondary waves of an earthquake which move up and down; these arrive slower than P-waves

seismogram

the paper output from a seismograph machine

seismograph

a sensitive piece of equipment used to measure and determine intensity of earthquakes

seismologist

a scientist - sometimes a geologist - whose study pertains to earthquakes

seismology

the science of using readings from a seismograph to determine intensity of earthquakes

shockwave

waves of energy that travel through the Earth's layers as a result of an earthquake; also known as seismic waves

T

tectonic plates

huge sections of the earth's surface that float on the mantle

transform plate boundary

boundary where two plates are moving past each other

tremors

the shaking or trembling of the earth is sometimes called a tremor; another word for earthquake

tsunami

a huge wave caused by sudden movement of the earth's surface - usually related to an earthquake or volcano

V

volcano

an opening in the earth's crust through which molten rock and gases are released