Mamoru KOARAI
Head of Geographic Information Analysis Division,
Geographical
Survey
Institute,
Ministry
of
Land,
Infrastructure and Transportation.
Specialty:
Geomorphology, Environmental Geology, Cartography,
Disaster Prevention, Remote Sensing, GIS
GIS ANALYSIS OF THE RELATIONSHIP BETWEEN
EARTHQUAKE DAMAGES AND MICRO LANDFORMS
USING LAND CONDITION MAPS
M. Koarai, H.P. Sato, H. Une, T. Kitahara
Geographical Survey Institute, Japan
koarai@gsi.go.jp, hsato@gsi.go.jp, une@gsi.go.jp, kitahara@gsi.go.jp
Introduction
It is known that there exists strong geographical relationship between the degree of
earthquake damages and micro landforms. In Japan, “land condition maps” have been
prepared by the Geographical Survey Institute (GSI) as a kind of basic thematic maps
covering all the major urban area since 1960s. They clarify the natural conditions of the
land by indicating the results of landform classification using aerial photo interpretation
method. In this paper, two GIS applications using land condition map are described.
The first application is the study on clarifying the geographical relationship between the
variations of micro landforms and the degree of earthquake damages by combining the
vector data of land condition maps and the information of earthquake damage distribution
using GIS, especially case of the 1854 Ansei-Tokai Earthquake, the 1891 Noubi
Earthquake and the 1944 To-Nankai Earthquake in Tokai District (Fig.1). The recent
publication of land condition maps in vector data format by GSI has enabled us to conduct
this kind of study, namely, the study combining various national land data using GIS.
The other application is the seismic strong motion hazard map using land condition map.
Fig.1
Index map of this study
Housing damage distribution by the 1891 Noubi Earthquake and land condition
In 1891 the Noubi Earthquake (M=8.1) occurred, and brought heavy earthquake
damages in the Noubi Plain including Nagoya City, Central Japan.
Fig.2 shows the land classification map of the Noubi Plain based on the land condition
maps “North Nagoya”, ”South Nagoya”, ”Gifu”, ”Ohgaki”, ”Tsushima”, and ”Kuwana”
published by GSI. Noubi Plain, formed by the deposition of three big rivers, the Kiso River,
the Nagara River and the Ibi River, consist of four areas such as alluvial fans, valley plain
or flood plain, coastal plain or delta, and reclaimed land from north to south. In the area of
valley plain or flood plain, natural levees exist along the rivers and former river beds.
Besides, artificially banked up area exists in and around Nagoya City.
Fig.2 Land condition of the Noubi Plain published by GSI
Fig.3 shows the distribution of ratio of housing damages by this earthquake (Muramatu:
1983). Housing damage ratio is estimated as follows: Ratio of housings damage
=
(numbers of completely destroyed houses + 0.5×numbers of half destroyed houses) / total
numbers of houses in studied area. The area where the ratio of housing damage is over
80% exists in the northwest part of the Noubi Plain. The authors produced the polygon data
from the distribution map of housing damage ratio, and overlaid this polygon data with
landform classification vector data of land condition map.
Fig.4 shows the ratio of each landform classification category in each housing damage
ratio range. Valley plain or flood plain and natural levee occupy in the high housing
damage area, where alluvial fan and terrace occupy in the low housing damage area.
Fig.3 Ratio of housing damage by the Noubi Earthquake in 1891 (Muramatu: 1983)
Artificially deformed area
100%
Water surface
Tidal flat
90%
Low water river bed
High water river bed
80%
River bed of Tenjo-gawa
70%
Former river bed
Surface ratio
Back marsh or interlevee lowland
60%
Coastal plain or Delta
Valley plain or Flood prain
50%
Dent or shallow valley
Sand (gravel) bank or sand bar
40%
Sand dune
Natural levee
30%
Gentle frontage of fan
20%
Alluvial fan
Debris avalanche
10%
Talus
Colluvial-like piedmont slope
0%
1019%
2029%
3039%
4049%
5059%
6069%
7079%
8089%
90- 100%
99%
Ratio of building damage
Terrace and table land
Unstable slope
Mountain slope
Fig.4 Ratio of each landform classification category in each housing damage ratio by
Noubi Earthquake
Housing damage distribution by the 1944 To-Nankai Earthquake and land condition
In 1944 the To-Nankai Earthquake (M=7.9) occurred off shore the Kii Peninsula,
Central Japan, and brought heavy earthquake damages in the coastal area of Enshu-nada
Region.
Fig.5 shows the land classification map of Enshu-nada Region based on the land
condition maps “Hamamatsu”, “Kakegawa”, “Iwata” and “Sumiyoshi and Omaezaki”
published by GSI. Three big rivers, the Kiku River, the Oota River and the Tenryu River
run in the Enshu-nada Region, and sand bank or sand bar exist along the coastline. In the
Ota River basin, valley plain or flood plain distributes in upper stream, and coastal plain or
delta distribute in lower stream. In the basin of Kiku River and other small rivers, valley
plain or flood plain distribute widely. In the Tenryu River basin, fluvial fan and natural
levee distribute in upper stream, and natural levee and valley plain or flood plain distribute
in lower stream.
Fig.5 Land condition of Enshu-nada Region by GSI
Fig.6 shows the distribution of ratio of housing damages by this earthquake (Ooba:
1957). Areas with high ratio distribute in fluvial plains along rivers. The areas with the
ratio of housing damage over 60% spread on valley plain of the Kiku River basin and
valley plain of the Ota River basin. The authors produced the polygon data from the
distribution map of housing damage ratio, and overlaid this polygon data with landform
classification vector data of land condition map.
Fig.7 shows the ratio of each landform classification category in each housing damage
ratio range.
Valley plain or flood plain widely occupies the area with high housing
damage ratio. Especially, occupation rate of valley plain or flood plain is over 40% in the
area with the housing damage ratio over 80%. Big occupation of coastal plain or delta in
the area with housing damage ratio between 20-79% is shown. However, coastal plain or
delta is under 15% in the area where housing damage ratio is under 20% or over 80%. The
ratio of natural levee is constant such as about 13% in each housing damage ratio range.
Fig.6 Ratio of housing damage by the To-Nankai Earthquake in 1944 (Ooba: 1957)
100%
Artificially deformed area
Water surface
Low water river bed
High water river bed
River bed of Tenjo-gawa
Former river bed
Back marsh or interlevee lowland
Coastal plain or Delta
Valley plain or Flood prain
Dent or shallow valley
Sand (gravel) bank or sand bar
Sand dune
Natural levee
Alluvial fan
Colluvial-like piedmont slope
Terrace and table land
Mountain slope
Surface ratio
80%
60%
40%
20%
0%
0-19%
20-39%
40-59%
60-79% 80-100%
Ratio of building all-damage
Fig.7 Ratio of each landform classification area in each housing damage ratio
Seismic intensity distribution of the 1954 Ansei-Tokai Earthquake and land condition
In 1854 the Ansei-Tokai Earthquake (M=8.4) occurred and brought heavy earthquake
damages in Enshu-nada Region.
The authors overlaid the point data of seismic intensity with landform classification
vector data of land condition map. Seismic intensity was estimated using the old
documents of temples (Namegata and Tsuji: 2006).
The large numbers of points with seismic intensity 6 are located on sand bank or sand
bar. Many points with seismic intensity 6 and 6.5 are located on natural levees and lower
terraces. Among locations of points with seismic intensity 5 and 5.5, ratio of fluvial fan is
high.
Application of land condition map for seismic strong motion hazard map
We have developed the seismic strong motion hazard map using landform classification
data of land condition maps. Table1 shows the relationship of seismic strong motion and
landform classification. Using this table, GSI produced new type seismic strong motion
hazard map based on land condition map. Fig.8 is a sample of seismic strong motion
hazard map of Suzaki Bay area, Kochi Prefecture, southern Shikoku Island (Fig.1). Left
part is landform classification of land condition map “Suzaki”, and right part is seismic
strong motion hazard map using landform information on land condition map.
Table1 Relationship of seismic strong motion and landform
Degree of
seismic strong
Landform classification
motion
Mountain slope, Land slide,
Small
Terrace and table land (Upper, High, Middle, Low)
Terrace and table land (Lower), Piedmont aggraded slope,
Less small
Alluvial fan, Sand dune
Natural levee, Sand (gravel) bank or sand (gravel) bar,
Middle
Valley plain or flood plain etc.
Less large
Dent or shallow valley, Coastal plain or delta, Former river bed
Large
Back marsh, Land reclamation area of water
Landform classification
Seismic strong motion hazard
Coastal plane
Fluvial plain
Reclaimed land
Back marsh
Sand bank
Mountain slope
Large
Less large
＊ Land condition map “Susaki”
Middle
Less small
Small
Fig.8 Landform classification map and seismic strong motion hazard map
(Sample of Suzaki Bay area)
Conclusion
Using vector data of land condition map, it is possible to combine several kind of land
information by GIS. In this research, the authors overlaid the landform classification data
of land condition map with distribution map of housing damages by large earthquake. On
terrace or fluvial fan, housing damages are relatively small. And on valley plain or flood
plain, coastal plain or delta and natural levee, housing damages are relatively large. From
the research results, the authors considered the relationship between earthquake damage
and micro landforms, and produced the seismic strong motion hazard map, based on
landform classification of land condition maps.
Acknowledgement
The authors thank for helpfulness of Mr. H. Murakami who works for GSI and Ms. Y.
Moriguchi who is graduated student of Tsukuba University, for producing GIS data of
housing damage distribution.
This work was supported by KAKENHI Grant-in-Aid for Scientific Research (B)
(18300314).
Reference
I.Muramatu, 1983, Distribution of the percentage of Collapsed Houses in the Nobi Plane
for the Nobi Earthquake of 1891. Science report of the Faculty of Education Gifu
University (Natural science), Vol.7, 867-882.
Y.Namegata and Y.Tsuji, 2006, Distribution of seismic intensities of the 1854 Ansei Tokai
earthquake in Shizuoka Prefecture estimated by the building damage records of temples.
REKISHI ZISIN, Vol. 21, 201-217.
S.Ooba, 1957, Study of the Relation between the Subsoil Conditions and the Distribution
of the Damage Percentage of Wooden Dwelling Houses in the Province of Totomi in the
case of the Tonankai Earthquake of December 7th, 1944. Bulletin of the Earthquake
Research Institute, Vol. 35, 201-295.