Site effects evaluated by detailed seismic intensity, peak acceleration and velocity, ground vibration by aftershock and microtremor, surface geology, and theoretical amplification on the ground in Akita City, Japan


Nogoshi, M.; Nakajima, N.

Proceedings of the 10th World Conference on Earthquake Engineering 1: 1019-1024

1992


Earthquake
Engineering,
Tenth
World
Conference
1992
Balkema,
Rotterdam.
ISBN
90
5410
060
5
Site
effects
evaluated
by
detailed
seismic
intensity,
peak
acceleration
and
velocity,
ground
vibratioh
by
aftershock
and
microtremor,
surface
geology,
and
theoretical
amplification
on
the
ground
in
Akita
City,
Japan
M.
Nogoshi
Akita
U
niversity.
Akita
City
Japan
N.
Nakaj
i
ma
Tokyo
Soil
Research
Co.
Ltd.
Japan
ABSTRACT:
Since
the
1983
Nihonkai
Chubu
earthquake
of
magnitude
7.7
occurred
in
the
Japan
Sea
about
100
km
west
of
Noshiro
City,Akita
Prefecture,Japan,many
investigations
and
studies
on
seismic
microzonaion
were
made
in
Akita
City,Noshiro
City
and
Honjo
City,Akita
Prefecture,Japan
First,we
obtained
the
detailed
seismic
intensity
at
subarea
of
about
250m
x
250m
throughout
Akia
City.
Second,we
analysed
the
strong-motion
accelerograms
of
54
components
on
the
1983
Nihonkai
Chubu
earthquake,and
obtained
some
attenuation
curves
of
peak
acceleration
and
velocity
in
northern
Tohoku
district,Japan.
Third,we
investigated
about
the
ground
vibration
by
the
after-
shock
and
microtremor
measurements
with
S-wave
velocities
on
the
ground
surface
in
Akita
City.
Forth,we
used
microtopographical
maps
of
Akita
City.
Fifth,by
using
many
boring
data,we
cal-
culated
the
amplification
of
the
ground
motion
at
each
subarea
of
about
250m
mesh
in
Akita
City
by
means
of
the
multiple
reflection
theory
of
SH
wave.
In
this
paper,
we
tried
to
overlay
and
evaluate
totally
such
terms
on
seismic
microzonation
as
the
detailed
seismic
intensity,peak
acceleration
and
velocity,microtopopraphy
and
subsurface
geology,ground
vibration
by
after
shock
and
microtremor,and
theoretical
amplification
on
the
ground
at
subarea
of
250m
mesh
in
Akita
City.
We
calculated
the
principal
components
between
these
terms,by
means
of
the
principal
component
analysis,and
discussed
the
site
effects
which
were
evaluated
by
the
principal
components.
1
INTRODUCTION
The
1983
Nihonkai
Chubu
earthquake
of
magni-
tude
7.7
occurred
in
the
Japan
Sea
about
100km
west
of
Noshiro
city,Akita
Prefecture,Japan,and
many
investigations
and
studies
on
seismic
mic-
rozonation
were
made
in
Akita
City,Noshiro
City
and
Honjo
City,Akita
Prefeture,Japan.
First,
we
obtained
the
detailed
seismic
inten-
sity
at
subarea
of
250m
x
250m
throughout
Akita
City
and
Noshiro
City,and
about
lkm
x
lkm
throu-
ghout
Akita
Prefecture,by
means
of
the
question-
naire
mehtod
of
Ohta,et
al.(1978)[Nogoshi,1988].
Second,we
analysed
the
strong-motion
accelero-
grams
of
54
components
on
the
1983
Nihonkai
Chubu
earthquake,and
obtained
some
attenuation
curves
of
peak
acceleration
and
velocity
in
northern
Tohoku
district,Japan[Nogoshi
and
Nakamura,1989a,1989b
and
1990].
Third,we
investigated
about
the
ground
vibra-
tion
by
the
aftershocks
and
microtremors
measurements
in
Akita,and
Noshiro
Cities
[Nogoshi,1985].
Forth,we
used
microtopographical
maps
of
Akita
City
and
Noshiro
City,which
were
investigated
and
drafted
by
a
geological
research
group
of
Akita
University(1986).
Fifth,by
using
many
boring
data,we
calculated
the
amplification
of
the
ground
motion
at
each
subarea
of
about
250m
mesh
in
Akita
City,by
means
of
the
multiple
reflection
theory
of
SH
wave.
After
we
investigated
these
terms
on
seismic
microzonation
of
the
ground
,first
we
perfomed
statistical
evaluation
between
site
effect
of
geological
conditions
and
de-
tailed
seismic
intensities[Nogoshi,1989],and
made
an
empirical
formula
for
estimating
the
detailed
seismic
intensity
by
means
of
multi-
ple
regression
analysis[Nogoshi,1990].
The
equation
of
detailed
seismic
intensity
con-
sisted
of
Kawasumi's
equation(1951),microto-
pography,subsurface
geology
and
depth
to
di-
luvium
or
tertiary
in
Akita
and
Noshiro
Cities.
Second,
we
discussed
relations
bet-
ween
the
detailed
seismic
intensity
and
the
peak
accelerations
and
velocities
in
Akita
Prefecture
and
Tohoku
district.
Third,we
re-
searched
into
microtremor
characteristics
at
area
in
Akita
City
and
Noshiro
City,damaged
Noshiro
City
and
Akita
City,which
damaged
by
soil
liquefaction
during
the
1983
Nihonkai
Chubu
earthquake[Nogoshi,et
al.1987].
In
this
paper,
we
tried
to
overlay
and
evaluate
totally
such
terms
on
seismic
micro-
zonation
as
the
detailed
seismic
intensity,
peak
acceleration
and
velocity,microtopo-
graphy
and
subsurface
geology,ground
vibra-
tion
by
aftershock
and
microtremor,and
theo-
retical
amplification
on
the
ground
at
sub-
area
of
250m
mesh
in
Akita
City.
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INVESTIGATION
TERM
Akita
City,Noshiro
City
and
Honjo
City
in
Akita.
Prefecture,northern
Japan
are
shown
in
Figure
1[Nakamura,et
al.,1989].
Our
investi-
gations
on
seismic
microzonation
of
the
ground
were
made
in
these
cities
for
1984-1990.
However,we
described
only
on
Akita
City
in
here.
After
the
1983
Nihonkai
Chubu
earthquake
occurred,the
microtpography
and
subsurface
in
Akita
City
and
Noshiro
City
were
investigated
by
Kotoda
and
Wakamatsu(1984)
and
Geological
Research
Group
of
Akita
University(1986).
In
Figure
2,we
showed
the
microtopographical
map
[Kotoda
and
Wakamatsu,1984]
with
areas
lique-
fied
by
the
1983
Nihonkai
Chubu
earthquake.
We
used
as
mesh
data
which
were
divided
the
mic-
rotopographical
and
subsurface
geology
data
into
each
subarea
of
about
250m
x
250m
through-
out
Akita
City,in
order
to
compare
with
other
investigation
terms.
Next,the
detailed
seismic
intensities
were
shown
in
Figure
3,as
a
part
of
distribution
at
subarea
of
250m
x
250m
throughout
Akita
City.
The
Numbers
are
represented
at
ten
times
as
many
as
the
detailed
seismic
intensity.
The
detailed
seismic
intensity
were
calculated
by
a
questionnire
method
of
0hta,
et
al.,imme-
diately
after
the
1983
Nihonkai
Chubu
earth-
quake
occuured.
Already,the
detailed
seismic
intensities
were
compared
statistically
with
geological
sites
at
subarea
of
250m
x
250m
in
Akita
City,and
this
comparison
were
made
on
Noshiro
City
and
throughout
Akita
Prefecture
[Nogoshi,1989].
As
the
results,the
detailed
seismic
intensities
were
corresponded
very
Aomori
Noshiro
Wmeshim
RI,
Japan
Sea
Akita
Morioka
Omono
Rio.
Honjo
50
km
Figure
1.
Locations
of
Akita
City,Noshiro
City
and
Honjo
City
in
Akita
Prefeture,
northern
Japan.(After
Nakamura
et
al.,1989)
Otdra
Roe.
Omono
Riv.
yamotoma
1.
Araya
to
Figure
2.
Subsurface
and
microtopographical
map
in
Akita
City.with
the
areas
liquefied
by
the
1983
Nihonkai
Chubu
earthquake.
(After
Nakamura
et
al.,1989)
Figure
3.
A
part of
distribution
of
detailed
seismic
intensity
at
subarea
of
250m
x
250m
throughout
Akita
City.
The
numbers
are
repre-
sented
at
ten
times
as
many
as
the
detailed
seismic
intensity.
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7
Peak
acceleration
and
velocity
Microtremor(
Ground
vibration
)
/
S-wave
velocity
Microtopography
Subsurface
geology
Theoretical
ampli
f
ication
Figure
5.
Overlay
model
of
term
data
of
250m
mesh
data.
/
Detailed
seismic
intensity
250
m
250
rn
Short-period
microtremor
characterization
was
investigated
in
detail
at
damaged
regions
in
Noshiro
City
and
Akita
City,where
damaged
by
soil
liquefaction
during
the
1983
Nihonkai
Chubu
earthquake.We
found
out
that
the
distinc-
tive
spectral
types
were
obtained
in
sites
damaged
by
liquefaction,
from
results
of
spect-
ral
studies
of
the
short-period
microtremors.
Predominant
period
and
peak
velocity
amplitude
of
the
short-period
microtremors
were
calcu-
lated
at
each
subarea
of
250m
mesh
in
Akita
City.
By
using
580
boring
data
and
S-wave
veloci-
ties,we
calculated
the
amplification
of
the
ground
motion
in
the
boring
sites,while
we
com-
puted
some
empirical
equations
estimating
S-
wave
velocities
in
Akita
City.
Moreover,the
theoretical
amplification
of
the
ground
motion
at
each
subarea
of
250m
mesh
were
computed
by
means
of
the
multiple
reflection'
theory
of
SH
wave(Figure
4).
S-wave
velocities
on
the
ground
surface
in
Noshiro,Akita
and
Honjo
Cities
were
measured
by
method
hitting
a
plate,with
re-
searching
into
undergroud
water
level,and
re-
lated
to
liquefied
sites[Research
Group
of
Short-
and
Long-Period
Microtremors,Saito,et
al.
,1988
a
a.n
pm
Figure
4.
Locations(*)
of
boring
data
at
sub-
area
of
250m
x
250m
throuout
Akita
City.
well
to
classification
of
soft
and
hard
micro-
topography
and
ground
surface
geology
in
Akita
City.
It
was
found
that
the
accuracy
of
the
detailed
seismic
intensity
was
0.1-0.2
from
standard
error
calculation.
Moereover,
we
made
an
empirical
formula
for
estimating
the
detail
ed
seismic
intensity
by
means
of
multiple
re-
gression
analysis[Nogoshi,1990].
In
Figure
4,locations
of
boring
data
at
sub-
area
of
250m
mesh
throughout
Akita
City.
580
boring
data
were
obtained
in
Akita
City,but
we
obtained
233
boring
data,after
we
selected
as
the
deepest
boring
datum
of
some
boring
data
at
each
subarea
of
250m
mesh
in
Akita
City.
Thickness
to
tertiary,depth
to
N-value=50
and
depth
which
N-value
changed
steeply
were
ob-
tained
as
three
informations
from
233
boring
data.
Next,we
analysed
the
strong-motion
accelero-
grams
of
54
components
on
the
1983
Nihonkai
Chubu
earthquake,and
obtained
some
attenuation
curves
of
peak
acceleration
and
velocity
in
nothern
Tohoku
district
and
Akita
Prefecture
[Nogoshi
and
Nakamura,1989].
Peak
acceleration
and
velocity
at
subaea
of
250m
mesh
were
cal-
culated
from
the
attenuation
curves
of
Akita
Prefecture.
We
investigated
about
the
ground
vibration
by
the
aftershocks
of
the
1983
Nihonkai
Chubu
earthquake
and
microtrmor
measurements
with
S-
wave
velocities
on
the
ground
surface
in
Akita
Noshiro
and
Honjo
Cities[Nogoshi„1985;Reserch
Group
of
Short-
and
Long-Microtremors,Nogoshi,
et
al.,1987].
1021
Also,we
researched
into
the
underground
water
level
from
boring
data
in
Akita
City
and
Noshiro
City.
Moreover,we
used
the
damage
investigation
data(total
collapse
and
half
collapse)
in
Akita
City
during
the
1983
Nihonkai
Chubu.
Earthquake.
Prop°.
Coef.
Propo.
and
Cum.
Prop.
SI,ONM,Dep,D50,M,S
(COR.)
Cum.P.
Coef.P.
I
II
III
IV
V
VI
Component
Figure
6.
C.P.
and
P.
of
principal
components.
Eigenvalues
of
the
CORRELATION
matrix
+1.e
[
3
SITE
EFFECT
EVALUATION
OF
OVERLAY
METHOD
We
tried
to
use
the
pricipal
component
analysis
as
a
method
to
evaluate
the
site
effects,that
is,we
tried
overlay
and
evaluate
totally
such
terms
on
seismic
microzonation
as
the
detailed
seismic
intensity,boring
data(depth
to
tertiary
,etc.),microtopography
and
subsurface
geology,
theoretical
amplification
on
the
ground,ground
vibration
by
aftershocks
and
microtremors
measurenients,peak
acceleration
and
velocity,
S-wave
velocity
on
the
groud
surface,under-
groundwater
level,and
damage
investigation
data
at
subarea
of
250m
mesh
in
Akita
City.
Eigenvalues
of
the
CORRELATION
matrix
Component
II
1.0
0.5
+1.0
+0.5
0
0.3
1.0
X(1)
X(2)
SI
DNM
ma)
X(4)
Dep
030
XIS)
X(6)
Figure
8.
Eigenvalues(Component
II)
of
6
variables.
+0.5
22
SI.INM.Dop.DS21.M.5
3
.*
*
*
*
*I
***.:
sr
**
*
-s
Figure
7.
Eigenvalues(Component
I)
of
6
variables.
Figure
9.
Scatter
diagram
of
z
1
and
z2
—1.0
0
—0.5
X(1)
Xt2)
SI
ANM
X(3)
3(4)
Dep
D58
XIS)
Xt6)
Component
'
I
0
—3
(CDR.)
sr
4
21
1022
Com
onont
I
+1.0
+0.5
—0.5
Component,
III
+1.0
+0.5
-e.s
of
the
detailed
seismic
intensity(SI),the
boring
data(DNM,Dep
and
D
so),the
microtopogra-
phy(M)
and
the
subsurface
geology(S),the
Ampli-
fication
(peak
amplification;BY8,predominant
period;BX',and
BYB
x
BX'),the
damage
invevsti-
gation
data(total
collapse;C,half
collapse;H).
As
shown
in
Figure
10,11,12,and
13,we
can
see
that
approximately,3
components(I,II,
and
III)
explain
totally
these
term
data(11
variables)
from
cumulative
proprtion(C.P.),and
component
I
shows
only
plus
eigenvalues
except
C
and
H,and
component
II
shows
plus
eigenvalues
except
BX'
and
MB x
BV,and
component
III
shows
lager
plus
eigenvalues
of
C
and
H.
Component
I
almost
is
similar
to
the
first
case,Conponent
II
and
III
are
complicated,but
it
is
estimated
that
the
detailed
seismic
intensity(SI)
is
closely
related
the
depth
to
tertiary(Dep),the
microto-
pography(Cand
the
damage
investigation
data
(C
and
H).
Figure
14
shows
a
scatter
diagram
of
scores(
zi
)
of
component
I
and
scores(
z2
)
of
component
I,and
Figure
15
shows
a
scatter
diagram
of
scores(
z
i
)
of
component
I
and
scores(za
)
of
component
III,with
the
mark
locations
of
damage
investigation
data(C
and
H).
As
shown
in
Figure
14,
toatal
collapse(C)
We
showed
an
overlay
model
of
such
term
data
of
250m
mesh
data
as
the
detailed
seismic
intensi-
ty,etc.in
Figure
5.
We
calculated
the
principal
components
between
these
terms,by
means
of
the
principal
component
analysis,and
discussed
the
site
effects
which
were
evaluated
by
the
prin-
cipal
components.
First,we
calculated
the
principal
components
of
the
detailed
seismic
intensities(SI),boring
data(depth
which
N-value
changed
steeply;DNM,
thickness
to
tertiary;Dep,depth
to
N-value=50;
D50),microtopography(Csubsurface
geology(S).
As
shown
in
Figure
6,7
and
8,we
can
see
that
approximately,2
principal
components(I
and
II)
explain
totally
these
term
data
from
cumulative
proportion(C.P.),and
component
I
shows
only
plus
eigenvalue,and
coponent
II
shows
plus
eigenvalues
of
SI,Dep,S
and
M.
This
result
explains
that
the
detailed
seismic
intensity
is
closely
related
the
depth
to
tertiary,the
sub-
surface
geology
and
the
microtopography.
Figure
9
shows
a
scatter
diagram
of
scores(z
)
of
component
I
and
scores(z
2
)of
component
II,and
this
explains
that
the
used
data
at
sub-
aea
of
mesh
is
equally
scattered.
Second,we
calculated
the
principal
components
Prapo.
Coef.
Prop°.
and
Cum.
Prop.
SI,DNM,D5e,Dep,M,S,BYB,EX',EYBxBX',C,H
CCOR.)
1.0
Cure.
P.
+0.5
0
+1.0
0.5
Coef.P.
0
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
Component
Figure
10.
C.P.
and
P.
of
principal
components.
Eigenvalues
of
the
CORRELATION
matrix
xii
)
IM4
1152
)
",4
)
xV
)
04%-
)
",1
0)
9
1)
Figure
11.
Eigenvalues(Component
I)
of
11
variables.
-0.5
Co
anent
II
—1.01
Xi)
IL4,
3 X
V
)
X
T
)
diax
,
xce
x'4"
Figure
12.
Eigenvalues(Component
II)
of
11
variables.
Eigehvalues
of
the
CORRELATION
matrix
xii
,
la
11.4
ayi4M-xce
x'4"
Figure
13.
Eigenvalues(Component
III)
of
11
variables.
Eigenvalues
of
the
CORRELATION
matrix
1023
SI.DNM,D30.Dep,M.S.BYLEX
.
dralx13X*.C,H
0
a
(CUR.)
CC
I
-
is
01.1
1
-
40
0C,H
0
Z2
5
-
0
-6
0
zt
Figure
14.
Scatter
diagram
of
z1
and
z
2
.
(CUR.)
CC
1
-
15
014
1
-
40
*C,H
0
a
*
-3
-6
0
21
Figure
15.
Scatter
diagram
of
z1
and
z3.
and
half
collapse(H)
are
closely
related
to
the
detailed
seismic
intensity(SI),the
depth
to
ter-
tiary(Dep),the
subsurface
geology(S)
and
the
microtopograohy(M).
As
shown
in
Figure
15
and
13,total
collapse(C)
is
approximately
similar
to
the
scatter
diagram
of
z
1
and
z
2
,
Moreover,
we
will
report
about
the
principal
component
as
total
term
of
seismic
microzonation
in
future
,in
addition
to
other
term
data,
for
example,
the
ground
vibration,
and
peak
acceleration
etc.
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23
8
SI.DN11.D50,D0p,1,S.EIMOV.IYINSX',C.H
0
1024