CCHS Earthquakes Brown

Amplitude

Height of a wave

Andrija Mohorovicic

Discovered the boundary between the crust and mantle, known as the Moho.

body waves

waves that travel through the interior of the earth

Compressional Stress

type of stress were rocks are squeezed or shortened

Deformation

General term for process of folding, faulting, shearing, compression, or extension of rocks as result of natural forces

Earthquake

shaking of Earth's crust due to a release of energy

Elastic Rebound Theory

theory that states most earthquakes occur as plates move, get stuck, bend and then break, releasing stored energy

epicenter

location along the surface directly above the focus of an earthquake

Fault

a crack in the Earth along which movement has occurred

fault creep

slow, gradual displacement that happens smoothly with little seismic activity

fault scarp

a cliff created by movement along a fault. it represents the exposed surface of the fault prior to modification by weathering and erosion

focus

location of an earthquake, within the earth, where the waves originate

Foot Wall

the block of rock that forms the lower half of a fault

H. F. Reid

Proposed the elastic rebound theory

head wall/hanging wall

the side of a fault that your head would hit

Inge Lehmann

a Danish seismologist and geophysicist. In 1936, she discovered that the Earth has a solid inner core inside a liquid outer core

Intensity

a measure of the amount of damage done to an area by an earthquake

landslides

caused when an earthquake destabilizes an already weak slope.

Liquefaction

when shaking of an earthquake caused saturated solid ground to turn into a liquid like pudding

Magnitude

the amount of energy released during an earthquake

Mercalli Scale

a scale that rates earthquakes according to their intensity and how much damage they cause

Moho

The boundary between the crust and the mantle, discovered by Andrija Mohorovicic

Normal Fault

an inclined fault in which the hanging wall appears to have slipped downward relative to the footwall

Primary (P) waves

travels fastest, compressional waves, can travel through solids, liquids and gasses

Richter Scale

a scale that rates an earthquake's magnitude based on the size of its seismic waves

S-P lag time

aka lapse time; difference in arrival time between the P and S waves

Secondary (S) waves

travel slower, side-to-side, shear, secondary, only through solids

Seismogram

The paper or digital recording of earthquake waves

Seismograph

an instrument that records earthquake waves

seismology

study of earthquake waves

Shadow Zone

an area on the Earth's surface where no direct seimic waves from a particular earthquake can be detected.

Shear Stress

layers being pushed in two different opposite directions

Strike-Slip Fault

a type of fault where rocks on either side move past each other sideways with little up or down motion

Subsidence

the gradual caving in or sinking of an area of land.

Surface waves

up and down motion, love and Rayleigh - types of surface wave, slowest of all waves, most dangerous

Tensional stress

The type of stress that tends to pull a body apart.

Reverse/Thrust Fault

fault in which the hanging wall slides over the foot wall.

tsunami

"harbor wave" and is created when the seafloor quickly deforms and displaces overlying waves

left lateral strike slip

type of fault where the ground on the opposite side of the fault is moving left with respect to the other block

right lateral strike slip

type of fault where the ground on the opposite side of the fault is moving right with respect to the other block

horst

higher blocks/ridges (either shifted upward or remaining stationary) on either side of grabens

graben

a block of crust between faults that has shifted downward in relation to the blocks on either side

Moment Magnitude Scale

An updated version of the Richter Scale that more accurately measures earthquakes that have a magnitude of 8.0 or higher.

shortening

decrease in the width of a fault block found at normal faults

extension

increase in the width of a fault block found at reverse faults

Hydraulic fracturing / fracking

Hydraulic fracturing, informally referred to as "fracking," is an oil and gas well development process that typically involves injecting water, sand, and chemicals under high pressure into a bedrock formation from a well.

Crest

Highest point of a wave

Trough

Lowest point of a wave