Method of using Geological data
for PSHMs in Japan
Hisanori MATSUYAMA and Nobuhiko TOYAMA(Oyo Corporation, Japan)

Hiroyuki FUJIWARA(National Research Institute for Earth Science and Disaster
Prevention：NIED)

Contents of presentation･ 1 objectives and character of the model.
･ 2 modeling methods and used data : 0thorder geological model.
･ 3 modifying the model : 1st –order model.
･ 4 conclusions and problems

1

Objective of the Model
Headquarters for Earthquake Research
Promotion (HERP)
National Research Institute for Earth Science and Disaster Prevention (NIED)
Earth Research Institute of Tokyo Univ. etc…
Observed waveform data
(K-NET, KiK-net etc…) →←3D deep subsurface

Seismic Faults datastructure model→

National Seismic Hazard Maps
Probabilistic Seismic Hazard Maps (PSHMs) etc…
→ on the Web : J-SHIS (Japan Seismic Hazard Information Station)“strengthening disaster prevention measures, particularly for thereduction of damage and casualties from earthquakes “Schematic overview of the subsurface
structure models
Shallow subsurface structure
Surface waves
Waves amplifying
Body waves

tens to hundreds of meters

Engineering bedrockVs ≈ 400 (300-700)m/s

Deep subsurface structure
Seismic source fault

several kilometers

Seismic bedrockVs ≈ 3,000m/s

Mohorovičić discontinuity

2

Outlines of
3D deep subsurface structure model・Based on geological data and geophysicalexploration data.
・Composed of different seismic velocity layers.
・Vertically divided into
cubes with about 1km
1km
mesh surface.
1km

Flow chart of modelingthe “Deep” subsurface structure
Subsurface structure data

Surface geological data

・Deep borehole, Logging
・Seismic reflection , refraction survey
・Micro tremor survey
・Gravity survey

・Topographical Map
・Geological Map

Distribution of physical properties

Structure of Sedimentary layers

・Seismic wave velocity ・Density

・depth ・thickness ･faluts ・folds

Layered structure model of physical property(0th-order geological model）

Model modification compared to observed waveform data
Simulation of seismic waveform using the Layered Model
Deep subsurface structure model for Strong-motion Evaluation(1st-order model）

3

Surface geological data(1)Geological Map 1:200,000(Geological Survey of Japan)

Foundation ofa geological model

These maps are compiled as“Seamless digital geological map of Japan
1:200,000” on the web.
using Geographic Information System (GIS) software.

Surface geological data(2)Geological Map 1:200,000
SHINJO AND SAKATA(Geological Survey of Japan)

In some areas, we can use deep geological profiles
down to 5,000m depth based on deep borehole.

4Surface geological data(3)<Surface distribution of seismic bedrock >Old sedimentary rocks
Plutonic rocks
Metamorphic rocks
Compiled from the data of Geological Survey of Japan

Surface geological data(4)<Surface distribution of sedimentary rocks>

Soft and low S-velocity ,amplifying seismic waves
Neogene rocks
Pliocene sedimentary rocks
Pliocene volcanic rocks
Late-Middle Miocene sedimentary rocks
Middle-Early Miocene sedimentary rocks
Early Miocene sedimentary rocks5

Deep borehole and seismic logging data
<Borehole and P-wave velocity : Niigata area>
P-wave velocity (km/s)
max scale : 7

velocity increasing
with depth

NeogenestrataSeismic survey data(1)Survey lines

not abundant survey data

Niigata area

Tokyo area

Data of “Japan Oil，Gas and Metals
National Corporation (JOGMEC）” ,“the Deep subsurface survey project”
by HERP ,“Japan Agency for MarineEarth Science and Technology(JAMSTEC）” and others.

6Seismic survey data (2)Seismic reflection, refraction survey data of Tokyo area
Depth

Neogene strata

0km- 1.7

1.7

2.0

2.0

2.0

2.1

1km2km-Miocene stratum

1.7

Pliocene-Pleistocene stratum

2.0
2.0
2.9

3.1

2.9

5.5
5.5

3km5.5

Seismic bedrock

P-wave velocity(km/s)

4km-

Data of the Deep subsurface survey project by HERP

Depth distribution from seismic survey
Depth distribution of the upper surface of example layers
Depth(m)Layer no.5 (Vs2.1km/s) upper surface

Upper surface of the seismic bedrock

7

Flow chart of modelingthe “Deep” subsurface structure
Subsurface structure data

Surface geological data

・Deep borehole, Logging
・Seismic reflection , refraction survey
・Micro tremor survey
・Gravity survey

・Topographical Map
・Geological Map

Distribution of physical properties

Structure of Sedimentary layers

・Seismic wave velocity ・Density

・depth ・thickness ･faults ・folds

Layered structure model of physical property(0th-order geological model）

Model modification compared to observed waveform data
Simulation of seismic waveform using the Layered ModelDeep subsurface structure model for Strong-motion Evaluation(1st-order model）

0th-order geological model(1)Depth distribution of the upper surface of example layers

00Layer no.5 (Vs2.1km/s) upper surface

00

Upper surface of the seismic bedrock8

0th-order
geological model(2)Geological Profile in Niigata area
Depth E-W (N37°45′)(m)「新竹野町」
南北断面

N91 A

00

「新潟平野」
南北断面「新竹野町」
東西断面「新津」東西・南北断面
東白根
TS-1

竹野町 -1

南郷K- D

朝日R-31

0-

Uo
Uo

UTd

Ny
LTd

5,000

Ny

SyLTｄNaGf角田山東縁断層10,000

Bs

Neogene strata
more than 5000m

新潟平野東縁断層帯

138°50′139°10′139°00′Flow chart of modelingthe “Deep” subsurface structure
Subsurface structure data

Surface geological data

・Deep borehole, Logging
・Seismic reflection , refraction survey
・Micro tremor survey
・Gravity survey

・Topographical Map
・Geological Map

Distribution of physical properties

Structure of Sedimentary layers

・Seismic wave velocity ・Density

・depth ・thickness ･faluts ・folds

Layered structure model of physical property(0th-order geological model）

Model modification compared to observed waveform dataSimulation of seismic waveform using the Layered Model
Deep subsurface structure model for Strong-motion Evaluation(1st-order model）

9

Peak-period ofobserved R/Vspectral ratio

peak period (sec)
>10
7-10
4-7
2-4
1-2
<1Difference of peak periods

S-velocity (km/s)

0Seismic observatory

123

40
1R/V spectral ratio

K-NET
KiK-netDepth (km)

23
40.1

1

period (sec)10

red circle : peak period of average observed R/V spectral ratio- gray lines : observed R/V spectral ratios- black line : average observed R/V spectral ratio- pink line : calculated H/V spectral ratio based on Vs andthickness of layers of the 0th-order geological model (right figure)

Model modification by comparison of observed
R/V and model-calculated H/V spectral ratios (1)Example : Hokkaido area
Difference of peak periods

Peak periods are the same

Modified layer
structure

0th-order geological model

Modified model10

1st-order velocity layered model(1)Depth distribution of the upper surface of example layers

modified area00000Layer no.25 (Vs2.1km/s) upper surface

0Upper surface of the seismic bedrock

Flow chart of modelingthe “Deep” subsurface structure
Subsurface structure data

Surface geological data

・Deep borehole, Logging
・Seismic reflection , refraction survey
・Micro tremor survey
・Gravity survey

・Topographical Map
・Geological Map

Distribution of physical properties

Structure of Sedimentary layers

・Seismic wave velocity ・Density

・depth ・thickness ･faults ・folds

Layered structure model of physical property(0th-order geological model）

Model modification compared to observed waveform dataSimulation of seismic waveform using the Layered Model
Deep subsurface structure model for Strong-motion Evaluation(1st-order model）

11

Comparison between observed and calculated
waveforms using the 0th-order, 1st-order models
Good correspondence !

-black line : observed waveforms-red line : calculated waveforms using 1st-order model-blue line : calculated waveforms using 0th-order model

Conclusions :･ Deep subsurface structure model based on geological
data covers all over Japan.
･ Modified model is useful to simulate strong motions
caused by future earthquakes and can be downloaded
from the website of "J-SHIS".
Several problems :･Deep subsurface structure model could be upgraded tomore precise one based on more and more geological andgeophysical exploration data.
･Deep model must be integrated with the shallow one.
･Modeling method calculating subsurface structures with
low-angled reverse-fault must be developed.

1246

Latest expanded model area

444240Depth distribution of the upper surface of example layers

3836

34

3434

33

33

3232

313130302929282827272626252524243230

123

124

125

126

127

128

129

130

Layer no.25 (Vs2.1km/s)
upper surface

131

123

128

124

125

126

127

128

129

130

130

132

134

136

138

140

142

144

146

131

Upper surface of the seismic
bedrockThat’s all.
Thank you for your attention .

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