Internal Structure of Earth Flashcards
a type of waves that can be classified as either a body
wave or a surface wave
seismic waves
define primary wave or P-wave
a longitudinal (compressional) wave
define secondary or s-wave
a transverse (shear) wave
TRUE/FALSE:
P-waves are the ‘slowest’ and they move through surface rocks and
sub-surface solid and liquid materials
FALSE; P-waves are the fastest
TRUE/FALSE:
S-waves are slower and they do not travel through liquids as P-waves do
TRUE
Why are S-waves slow and why can’t they travel through liquids?
liquids do not have the cohesion needed to transmit a shear, or side-to-side, motion
define surface wave
up-anddown (crest and trough) and side-to-side waves that travel across the surface
TRUE/FALSE:
surface waves
are the slowest among all the waves
TRUE
What are the two types of surface waves?
Love waves and Rayleigh waves
Who discovered Love waves?
Augustus Love
Who discovered Rayleigh waves?
Lord Rayleigh
TRUE/FALSE:
Love waves are ‘vertical’ surface waves, moving from side to side.
FALSE; Love waves are HORIZONTAL surface waves
Love waves: horizontal surface waves; Rayleigh waves: __________
up and down
TRUE/FALSE:
seismic waves travel most rapidly in rigid materials
TRUE
How come seismic waves can travel faster in deeper areas?
deeper areas experience much higher
pressure, causing the rocks there to become more compact
define discontinuity
the boundary between the two unlike materials
Enumerate the Earth’s three zones
crust, mantle, and
core
Earth’s outer layer and is very thin
crust
Oceanic crust is generally made of a denser rock called ________
basalt
Continental crust is a less
dense, _________ rock.
granite-type
Between the crust and the layer below it, (mantle) is the boundary known
as the __________
Mohorovičić discontinuity
Who discovered the Mohorovičić discontinuity and when was it discovered?
Andrija Mohorovičić in 1909
A layer of the Earth that’s soft and a relatively weak layer located in the upper
mantle
asthenosphere
At the uppermost part of the asthenosphere, _______________ occurs
partial melting
the partial melting of the asthenosphere is called _______________
low-velocity zone
an iron rich sphere at the center part of Earth
core
part of the mantle found below the lithosphere; a “weak sphere”
asthenosphere
the very thin outermost layer of Earth
crust
boundary between two unlike materials
in the interior of Earth as determined by
the behavior of seismic waves
discontinuity
ocation on Earth’s surface that lies directly above the focus of an earthquake
epicenter
boundary between the mantle and the core
Gutenberg discontinuity
rigid outer layer of Earth, including the crust and upper mantle
lithosphere
part of the mantle characterized by a
decrease in the velocity of seismic waves
low-velocity zone
thick layer of Earth located below the crust
mantle
also called Moho; the boundary between
the crust and the mantle characterized by
an increase in seismic velocity
Mohorovičić discontinuity
layer beneath the mantle which has the
properties of a liquid
outer core
a wave that compresses and
expands the material through which
it moves; a longitudal wave; fastest
earthquake wave
P-wave
a wave that vibrates the particles of its medium up-and-dowm and sideto-side; a transverse wave; slower than a P-wave that travels only in solids
S-wave
an instrument that records earthquake
waves
Seismograph
study of earthquakes and seismic waves
seismology
zone between about 103° and 142° distance from the epicenter of an earthquake which direct waves do not penetrate because of the refraction by Earth’s core
shadow zone
TRUE/FALSE:
Seismic waves are
reflected and refracted (or bent) at boundaries of unlike materials
TRUE
