Page 214 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists
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components.
given
Love
waves, so
197
between
a
Interference of Love and Rayleigh
Interference of Love and Rayleigh
Earthquakes
In
south-southeast
arrivals of
Rayleigh
focus.
waves.
east-west
interference
%
Rayleigh)
the
to
than
three seismometers, responding
of
Only Rayleigh
an earthquake located
from
Characteristics
and
=P
faster
=
north-south
to
outward
Love, R
slightly
due
complex,
=
radiate
(L
travel
R
surface
the
from
R)
«<i
(L,
on
waves
paths
=
more
S
P-waves
shear) and
4 1 ' 1 ' 1
of the
\
Zz
initially
z
wave
is
Love
from each
pattern
Mechanisms
j.__
Body and surface
occurs,
Ff
appear
S =
7
First Motion
First Motion
Up—~
North~_
(Fig. 7.12b).
First Motion
compressional,
West
of a station. b) Seismograms
wave
earthquake
waves
waves.
(N)
(E)
surface
Component
Component
Component
Vertical (Z)
&
a)
Focal
North-South
wave
Love
East-West
Rayleigh
=
7.12
body (P
an
later
Rayleigh
only
Earthquake
FIGURE
When
that
the
b
and
The
&
:
may
“
;
:
;
surface followed (compression), front in material compress first might wave the direction, might wave the direction, another In (dilatation). material the of stretching apart by seis- as station a at Earth the from out coming P-waves first from compress. The then and stretch the (dilatation) downward or (compression) upward
motion ata Figs. 3.8, 3.12). wave. compressional and body of differently respond waves by taken an For for (seismograms) initial The 7.12. came P-wave the motions First compression come have must Love for Z-component the
three orthogonal components of ground body waves (see also horizontal shear wave; P = motions particle the seismometers paths different the motions. particle different recordings in illustrated Fig. revealing upward, that the upward. ground show the that therefore wave the Z-component) (no motion on appearing
Seismology particle motions for surface and = of view simplified three 3. The to due station, the as well station, the of patterns the is Z-component pushing components E-W westward; than up-down no wave surface of
Earthquake Seismographs measuring the Simplified vertical shear wave; SH = shows a Chapter in arrive the at as station, south-southeast show would the on compression, a as and N-S the northward is there that type only the
Chapter 7 7.10 seismic station. 7.11 FIGURE shear wave; SV 7.11 Fig. explained waves waves mic the to focus occurring seismometers motion) (first ground the on P-wave more ground direction. SSE Notice 3.12); (Fig.
196 FIGURE = S