Page 204 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

Crust
Boundary
-
by
because
Focal
epicen-
(or
Earth
Earth’s
focus
earth-
187
extends
earth-
described
focus
Asthenosphere
failure.
deep
Most
focus
Plate
the
Earthquakes
the
on
lithosphere
Earth,
The
point
within
all
from
7.3).
shallow
brittle
be
7.2).
Transform
virtually
the
can
distance
(Fig.
the
of
volume)
_- Crust
(Fig.
Boundary
of
undergo
where
depth;
earthquake
km
is
Characteristics
boundary
and
epicenter
rupture
700
the
settings,
km
small
depth)
b)
can
upper
is
70
of
depth
plate
Plate
which
an
The
(relatively
to
(subduction)
zone
km
the
of
boundaries.
7.3c).
surface
of
The focal
released.
location
lithosphere,
300
Convergent
in
the
type
occur
(Fig.
of
to
the
“point”
the
_/ Crust

(70
depth
asthenosphere
The
is
focus.
Earthquakes
convergent
Boundary
of plate
from
to
energy
focus
rigid
related
and
Epicenter
actual
the
focus,
c)
the
types
intermediate
longitude,
Earthquakes
earthquake
above
Asthenosphere
in
to
normally
shallow
the
the
Plate
occur
all
confined
Depth
and
directly
focus.
at
through
is
occur
earthquakes
latitude,
hypocenter)
Divergent
Focus
are
are
Focal
Most
the
the
are
of
surface
quakes
quakes
deeply
depths
where
J
to
Location
they
the
ter
a)
FIGURE a) Only crust and uppermost Positions and depths to earthquakes (black dots) along different types of plate boundaries, 7.3 mantle are cold and brittle enough to produce earthquakes along divergent boundaries. b) Earthquakes occur in the upper (cold) part of the lithosphere at transform boundaries. c) At convergent boundar

through earth- be must and Other fluidly, lower to to the near Law, it fashion, released off sends Stress view of a
be in there limit; and The subjected confined Hooke’s is Relieve and depth
could results 1) elastic lithosphere. ductilly time. of not exclusively concentrated brittle energy which fault, or cross-sectional Rocks initially behave elastically as
failure situation necessary: its beyond the is behave periods are they are obeying a in strain earthquake, Rebound to (Fig. 3.1c). If brittle failure occurs, stored energy is Cross section of a rupturing fault, illustrating terminology location
limit, latter thus criteria long but stresses stressed, fails rock stored an —_c) to new positions across the fault, seismic waves radiate from the as 7.2 to describe the
elastic its The 3.2). are factors material the above the core, outer over applied solid, are are, therefore, almost where be can rock the If 3.1c). the as is energy Elastic Limit 5 ee Feut either map view of a strike-slip undeformed state. b) i FIGURE used of an earthquake.
Seismology EARTHQUAKES beyond stressed 3.1, (Figs. fracture two occur, to stress will that fracture. brittle fits that Earth and asthenosphere are stresses core inner the Earthquakes particularly that states (Fig. limit position new strain of release Stressed to represent rocks is reached of the ek nv cP Earth's
Earthquake OF Theory is material brittle or earthquakes movement by fail must the of region the as large when and (mesosphere) stresses. lithosphere, rigid of plates. theory rebound elastic its a into (snaps) sudden waves. seismic b) Elastic rebound. Figure can fault. a) Sequence of rocks in (Fig. 3.1b).c) Elastic limit earthquake. rocks rebound The focus). €? wee
Chapter7 CHARACTERISTICS Rebound Earth When flow ductile For quakes. of sort some material the The such regions, respectively, mantle differential large moving, the boundaries Elastic reaches it until rebounds The 7.1). (Fig. as vibrations Undeformed Rocks or reverse) rupture zone (earthquake
186 Elastic 2) 7.1 dip-slip (normal stress is applied as an
a) FIGURE released