Page 64 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

;
,
‘
(for
of
that
47
their
Earth
the
and
to
under
direc-
the
volume
divided
pertains
portion
within
describes
isotropic
properties
factors
222-230);
the
Waves
all
material
stress
in
in
through
change
that
material
thus
equal
many
material.
considezed
Elastic
the
“incompressibility”)
pp.
to
of a
physical
below
is
is
refers
are
the
by whether they travel
1976.
that
strain
(k)
for
homogeneous
is
waves). There
analysis
modulus
same
“lithostatic”
strain
al.,
Under pressure
Unbounded
be
the
stress
rey
et
can
elastic constant describes
the
(see Telford
(AP). The
interfaces. The
AV/V
material
applied
bulk
AP
has
ein
(or
(surface
a
water;
.
directions.
material
of such
(V). The
modulus
ees the
3.5).
elastic
pressure
categorized
sain
Stress

waves
Eaves
under
under
surface
“body”
resist being compressed.(Fig.
or
the
volume
is simplified, however, if the
_
all
bulk
body
surfaces
in
k
that
material
pressure
its
in
change
Earth’s
be
the
rigidity)
Panna
The
An
original
of
means
can
through
propagation
free
stress.
for
confining
pi
3.4)
the
Propagation
Constants
along
x poicen al
Isotropic
and
no
(“hydrostatic”
the
is
(Fig.
ot
moving
of
with
5
stress
peop!
density
or
by
:
type
Seismic waves
' =
divided
waves)
the
es
strain:
Elastic
material
unbounded.
‘
the
P’
vibrations
certain
influence
to
example,
Wave
analysis
Earth),
where:
the
ability
(body
(AV)
tions
the
by
a
Body
: AP by caused volume in change = V' — V AV = It original V = volume ul stress. applied the under volume V’ = ‘ no undergoes material a if that illustrates equation above The change volume (AP), stress compressive to subjected when 0) = (AV be to said is material the is energy wave Surface 3.4 FIGURE confined to a thin, outer s

is of the shows of parti- flows an of the an few results in rates, as
stress amount others. deforming time level that removed. as from elastically a underlying remain connected strain (ductile) of overlying
the the under the of 3.1¢ Fig. certain so is material rupturing behavior results only at the Inelastic
when where inelastic of length rate). a to fails, stress the the behaves move motion, a) During ductile particles Brittle deformation
shape 3.1c). orientation the 2) (strain up only material the whereby lithosphere by of particles plates this flow. b) the development of fractures. a) Elastic behavior occurs at very high of seismic waves. b)
and behavior (Fig. conditions, and Law) the when ductile, the illustrated movement asthenosphere with fashion. oe 3.2 formation and
volume elastic of stress some and shearing); of distortion Hooke’s limit that positions be or breaking is rate) rapid the Lithospheric associated (ductile) the passage
original describes amount under magnitude or tension, amount (obeying Beyond original may limit pencil (that is, strain very rates strain waves. rates ; in very slow straining of the asthenosphere; viscous flow facilitates the movement
its Law the to elastic the 1) certain limit. a but seismic inelastic b) Brittle Deformation
to be elastic their elastic like time Small high strain an
Waves returns Hooke’s proportional may are: compression, a achieve be elastic to the brittle, of 3.3). very transmit slow in Elastic and inelastic behavior of the asthenosphere. by an earthquake; the vibrations result
Seismic material 3.1b). (Fig. linearly materials factors of (amount to takes may material the as return not beyond or putty, 3.2). (Fig. importance (Fig. these at to able very the deforms 325 i] 4s s-=-=*”' -“Asthenosphere
Chapter 3 the that removed is strain Earth important Two stress material a that known stress, do cles Deformation silly like earthquake The asthenosphere earthquake; thus is and at cm/year; asthenosphere a) Ductile - Deformation go moe oN. x emo
46 3.3 particles are vibrated behavior results from lithospheric plates.
FIGURE