ES Ch 8 EQ's & Earth's Interior

earthquake

vibration of Earth produced by rapid release of energy within lithosphere

fault

break or fracture in lithosphere where movement has occurred during EQ

focus

point within Earth where EQ starts

epicenter

location on surface directly above the focus

seismic waves

energy released by EQ that travels in all directions

fault creep

slow gradual movement along a fault

elastic rebound

tendency of deformed rock along fault to spring back after EQ

aftershock

EQ that occurs sometime soon after major EQ

foreshock

small EQs before major EQ

P & S

What are the types of body waves?

P

push-pull waves that push (or compress) & pull (or expand) particles in the direction the waves travel

P

Which wave travels the fastest?

S

Which wave does NOT travel through liquids?

S

shake particles at right angles to waves' direction of travel (transverse wave)

surface wave

seismic wave that move up & down as well as side to side

seismograph

instrument to record seismic waves

seismogram

time record of ground motion during EQ

intensity

measure of amount of EQ shaking at given location based on amount of damage

magnitude

measure of size of seismic waves or amount of energy released at source of EQ

Richter

based on height of largest seismic wave (P, S or surface) recorded on seismogram

Moment magnitude

amount of displacement that occurs along fault

moment magnitude

scale used by scientists

modified mercalli

rates EQ's intensity in terms of EQ's effects at different location

travel-time graph

data from seismograms made at 3 or more locations & globe can be used to determine EQ's epicenter

seismic shaking

ground vibrations caused by seismic waves

liquefaction

when soil & rock saturated with water, EQs can turn stable soil into liquid

tsunami

wave formed when ocean floor shifts suddenly during EQ

along boundaries of Earth's plates

Where do most EQ's take place?

seismic gap

area along fault where there has not been any EQ activity for long period of time

base isolators

building mounted on large rubber & steel pads which absorb energy of seismic waves

crust

thin, rocky outer layer of Earth

oceanic

Which type of crust is younger?

continental

Which type of crust is thicker?

continental

Which type of crust is made of granite?

oceanic

Which type of crust is made of basalt?

mantle

solid, rocky shell that extends to depth of 2890 km

core

sphere composed of mostly iron-nickel alloy

lithosphere

Earth's outermost layer, which consists of crust & uppermost mantle & forms relatively cool, rigid shell

asthenosphere

soft, comparatively weak layer beneath lithosphere

outer core

flow of metallic iron within this zone generates Earth's magnetic field

inner core

despite high temps, materials compressed into solid state by immense pressure

moho

boundary separates crust from underlying mantle

shadow zone

region where bent P waves arrive

surface

Which waves are most destructive?

Pacific

Which ocean has tsunami warning system?