A consideration of operational risk for slope disasterin the NOTO Peninsula earthquake
Tomoo Dobashi 1, Sadao Kimura 2
1

Dept. of C i v i l a n d E n v i r o n m e n t a l E n g i n e e r i n g , Kanazawa Institute of Technology
E-mail : dobashi_123@jupiter.kanazawa-it.ac.jp
2
Dept. of C i v i l a n d E n v i r o n m e n t a l E n g i n e e r i n g , Kanazawa Institute of Technology
E-mail : s.kimura@neptune.kanazawa-it.ac.jp

NOTO Peninsula earthquake of seismic intensity a little over 6 occurred in Ishikawa in 2007. By thisearthquake, the damage occurred in many civil engineering facilities. Above all, the damage of the slope
holds about 80% of the damage amount of money in the total civil engineering facility. On the other hand,road disaster prevention inspection is established in 1968 and checks the situation of the slope, the effectof the existing measure method of facility, the history of the disaster. Therefore, in this paper wecompared the true damage that occurred by NOTO Peninsula earthquake with the judgment result of riskof the road disaster prevention inspection, and examined the effectiveness of the judgment method of roaddisaster prevention inspection. As a result, check was inapplicable, and there were about 80% damage
points in the total slope damage number. At the damage point out of a prevention inspection object,surface of deform held most. In addition, about 60% of the damage points were judged appropriately
when we converted it into a reconstruction cost.

1.

INTRODUCTION

The natural disaster such as an earthquake or thetyphoon occurs in Japan. And in late years,large-scale natural disaster occurs. In March, 2007,
NOTO Peninsula earthquake (M6.9) occurred. By
this earthquake, the damage amount of money of
the whole civil engineering facility was about
24,200,000,000 yen. In particular, the damage
amount of money of the civil engineering facility is
about 19,300,000,000 yen and occupies about 80%of the total damage amount of money 1). Figure 1
shows the damage point of road facilities by theNOTO Peninsula earthquake.
On the other hand, for improvement of the disasterprevention power of road installations, road disasterprevention inspection 2) (the following, theprevention inspection) is carried out from 1968. The
prevention inspection is classified into an
earthquake countermeasure, a heavy rain and aheavy snow countermeasure. By the prevention
inspection of the earthquake countermeasure,collection of information that is necessary for a
judgment of the quake resistance of the roadstructure (a road, a bridge, a tunnel) is performed.
By the prevention inspection of a heavy rain and aheavy snow countermeasure, three phases of(measuresrequired,continualobservation,measures unnecessary) evaluation is performed inan inspection point.
This study focuses attention on the road slope andcompared the damage result of the prevention
inspection with the damage by the NOTO PeninsulaExplanatory notes㽢 Epicenter䖃 Roadfacilitiesdamage䕿 Thepreventioninspection

Fig.1 Road facilities damage spot by
the NOTO Peninsula earthquake
Table.1 The judgment standard of the degree ofrisk of the slope for the heavy rain and heavy
snow countermeasure㻳㼑㼚㼑㼞㼍㼘㻌㻱㼢㼍㼘㼡㼍㼠㼕㼛㼚㼟㻶㼡㼐㼓㼑㼐㻌㼚㼑㼏㼑㼟㼟㼍㼞㼥㼙㼑㼍㼟㼡㼞㼑㼟㻼㼑㼞㼒㼛㼞㼙㻌㼏㼛㼚㼠㼕㼚㼡㼍㼘㼛㼎㼟㼑㼞㼢㼍㼠㼕㼛㼚㻰㼛㻌㼚㼛㼠㻌㼚㼑㼑㼐㻙㼑㼟㼜㼑㼏㼕㼍㼘㼘㼥㼚㼑㼣㻌㼙㼑㼍㼟㼡㼞㼑㼟㻱㼢㼍㼘㼡㼍㼠㼕㼛㼚㼟㻌㼛㼒㻌㻯㼛㼚㼠㼑㼚㼠㼟㻼㼛㼕㼚㼠㻌㼣㼔㼑㼞㼑㻌㼒㼍㼏㼠㼛㼞㻌㼣㼕㼠㼔㻌㼜㼛㼟㼟㼕㼎㼕㼘㼕㼠㼥㻌㼠㼛㻌㼐㼕㼟㼍㼟㼠㼑㼞㻌㼕㼟㼛㼎㼢㼕㼛㼡㼟㼘㼥㻌㼍㼐㼙㼕㼠㼠㼑㼐㻚㼀㼔㼑㻌㼜㼛㼕㼚㼠㻌㼠㼔㼍㼠㻌㼙㼍㼚㼍㼓㼑㻌㼎㼥㻌㼙㼛㼚㼕㼠㼛㼞㻌㼣㼕㼠㼔㻌㻯㼛㼚㼠㼕㼚㼡㼍㼘㼛㼎㼟㼑㼞㼢㼍㼠㼕㼛㼚㻌㼒㼛㼞㻌㼠㼔㼑㻌㼠㼕㼙㼑㻌㼎㼑㼕㼚㼓㻌㼍㼘㼠㼔㼛㼡㼓㼔㻌㼠㼔㼑㼚㼑㼏㼑㼟㼟㼍㼞㼥㻌㼕㼟㻌㼍㼟㼟㼡㼙㼑㼐㻌㼕㼚㻌㼠㼔㼑㻌㼒㼡㼠㼡㼞㼑㻚㼀㼔㼑㻌㼜㼛㼕㼚㼠㻌㼠㼔㼍㼠㻌㼎㼑㼏㼛㼙㼕㼚㼓㻌㼠㼔㼑㻌㼒㼍㼏㼠㼛㼞㻌㼛㼒㻌㼠㼔㼑㻌㼐㼕㼟㼍㼟㼠㼑㼞㻌㼕㼟㼚㼛㼠㻌㼐㼕㼟㼏㼛㼢㼑㼞㼑㼐㻌㻘㻌㼐㼛㻌㼚㼛㼠㻌㼚㼑㼑㼐㻌㼜㼍㼞㼠㼕㼏㼡㼘㼍㼞㼘㼥㻌㼚㼑㼣㼏㼛㼞㼞㼑㼟㼜㼛㼚㼐㼑㼚㼏㼑㻚

Table.2 The Disaster spot number ofpublic civil engineering facility
Road River Bridge Steep slope Shore
646 151 19
98Erosion and Sediment control
6

Landslide Total
3842


earthquake, and examined the effectiveness of thejudgment technique of the prevention inspection.
An object facility is Ishikawa management road (asupporting national highway, a prefectural road, amajor regional road).

Table.3 A classification result of thedamage situation
Road classification2. THE PREVENTION INSPECTION

Supporting national highway
Prefectural road
Major regional road
Total

Disasters data䠄Damage of road facility䠅
Slope
Other138227971814458323

Table.4 The enforcement situation of(1) Experimental overview
prevention inspection at the slope disaster point
The prevention inspection in 1996 judges degree
Slope of disasterof risk at the slope for the heavy rain and the snow
Inspection spotmeasures. Described in the road earthquake disaster
InOut
Other
measure manual (preseismic countermeasure), for
Supporting national highway
490
PrefecturalroadRoadclassification
0270example, ridge topography and slope with many
Major regional road
5121
cracks occurs slope disaster 3). Described in theTotal948
1
prevention inspection, risk assessment method inheavy rain countermeasure and heavy snow
countermeasure give close agreement with㼀㼔㼑㻌㼞㼑㼟㼠㼛㼞㼍㼠㼕㼛㼚㻌㼠㼛㼜㻌㼢㼕㼑㼣inspection method that described in the roadearthquake disaster measure manual. Table 1
showed the judgment standard of the slope in theprevention inspection. At present, in the case theevaluation for the earthquake disaster of slope, notonly think about the earthquake disastercountermeasure but also think about the measure of
the slope failure by cause except the earthquake
Fig.2 A figure of restoration top view of themeasure. We suppose that this evaluation result isdisaster spot
effective as evaluation technique for the earthquake㻭㻌㻾㼑㼏㼛㼞㼐㻌㼛㼒㻌㼟㼘㼛㼜㼑in this study.
(2) Classification of the road facilities damage
and the identification of the slope disaster.
㻸 㼛 㼏 㼍㼠㼕 㼛 㼚㼟㼗 㼑 㼠 㼏 㼔㼒㼕
Table 2 showed the damage point number ofpublic facilities by the NOTO Peninsula
earthquake. At first, identification of the disasteroccurred point of the slope is necessary to grasp thedamage of the slope by the NOTO Peninsula
earthquake.
The damage of road facilities to show in table 2
becomes all damage including the slope damage.
Therefore, we extract the slope disaster from thisFig.3 A record of the disaster point
damage. We use a disaster date (a restoration top
Table.5 Definition of prevention inspection
view, a restoration cross section and a restoration
result with “Correct” and “Incorrect”
method of construction) for the extraction of theSlope disaster
HappenNot happen
slope disaster. Table 3 is the result that extracted ofMeasuresrequiredCorrect
Incorrect
the slope disaster.
According to the disaster date, there is not
Inplementation Continual observation
Near Correct
Near Correct
Total inspection
information to make the position of the slopepoint
Technical-Incorrect (error of
Measures unnecessary
Correct
disaster clear. The specific result of the disasterthe first kind)point is expressed in the latitude longitude of theSelect-Incorrect(errorNot Inplementation
Correctof the second kind)disaster point. Therefore, we quote the browsing
system fundamental geospatial date and the aerialTable.6 The comparison result of the slope
photograph of the goo map and identify thedisaster㸦About the disaster number㸧
disaster point.
(3) The identification of the position of a
Correct Near Correct T-Incrrect S-Incorrect OtherTotal
2048
158
disaster point and the prevention inspection Slope of disaster 7
䠄unit䠖number䠅
point




It is necessary to identify a damage location andthe prevention inspection point in detail to grasp aslope disaster by the earthquake. The prevention
inspection point is already grasped in latitude
longitude. Therefore, we identify the position of adisaster location and the prevention inspection
point. Figure 2 and figure 3 showed the example ofthe data which used for the identification. About
83% slope damage understands a thing than thisbesides a prevention inspection point. The
comparison result of the identification of thedamage point and the prevention inspection point isgiven in table 4.

Table.7 The comparison result of the slope
disaster㸦About a restoration cost㸧
Correct Near Correct T-Incrrect S-Incorrect Other
slope of disaster 2,075,935

133,0150

1,329,805

Total

3,346

3,542,101䠄denomination䠖1,000yen䠅

Table.8 The classification result of theslope disaster
Correct Near Correct S-Incorrect T-Incrrect OtherTotal

Slope of failure

116019Natural hill of failure

4160011Surface of deform

20360038Total

72480158

3. COMPARISON OF PREVENTIONINSPECTION RESULT AND NOTOPENINSULA EARTHQUAKE DAMAGE

㻻㼠㼔㼑㼞
㻞㻑

㻻㼠㼔㼑㼞㻜㻑

㼀㼑㼏㼔㼚㼕㼏㼍㼘㻙㻵㼚㼏㼛㼞㼞㼑㼏㼠㻜㻑㼀㼑㼏㼔㼚㼕㼏㼍㼘㻙㻵㼚㼏㼛㼞㼞㼑㼏㼠㻜㻑㻯㼛㼞㼞㼑㼏㼠㻝㻞㻑(1) Definition of the prevention inspection resultwith "Correct" and "Incorrect".
Definition of the prevention inspection result anddamage result is given in Table 5. "Correct"
expresses that the true damage accords with theprevention inspection result.
Both "Technical-Incorrect" and "Select-Incorrect"
mean "error of the first kind". "Technical-Incorrect"
means "Technical" from that involved in evaluation
methodoftheprevention
inspection.
"Select-Incorrect" means "Select" from thatinvolved in the extraction method of the prevention
inspection point. We do not focus on "Incorrect"
number to consider the damage of unexpected roadadministrators. The “Incorrect” means “error of thefirst kind”.
(2) Comparison of a prevention inspection result
and the damage result
The comparison result of the prevention inspectionresult and the damage result is given in table 6. As
for the slope disaster, the numbers of 7 were“correct”, and the numbers of 48 were“S-incorrect”. Next, we clarify a restoration cost at
each evaluation of the prevention inspection result.
Table 7 shows the restoration cost at eachevaluation of the prevention inspection result. As
shown in figure 4, represents a ratio of the numberof ͆Correct͇ and ͆S-Incorrect͇, in the casefocused attention on the number of slope disastersand restoration cost. As shown in Figure 4(a),represents the ratio of the number of each
"Incorrect" and "S-Incorrect", in the case focusedattention on the slope disaster number. As shown inFigure 4(b), represents the ratio of the amount ofmoney of each "Incorrect" and "S-Incorrect", in thecase focused attention on the restoration cost. As
shown in figure 4(a), the ratio of "Incorrect"
accounts for about 15% of the total, and㻿㼑㼘㼑㼏㼠㻙㻵㼚㼏㼛㼞㼞㼑㼏㼠㻟㻣㻑㻺㼑㼍㼞㻌㻯㼛㼞㼞㼑㼏㼠㻟㻑㻿㼑㼘㼑㼏㼠㻙㻵㼚㼏㼛㼞㼞㼑㼏㼠
㻤㻟㻑

D 7KHUDWLRRIWKHGDPDJHQXPEHU

㻯㼛㼞㼞㼑㼏㼠㻡㻥㻑㻺㼑㼍㼞㻌㻯㼛㼞㼞㼑㼏㼠㻠㻑

E 7KHUDWLRRIWKHUHVWRUDWLRQFRVWFig.4 The ratio of the slope disaster of the"Correct" and "Incorrect"
㼀㼔㼑㻌㼞㼑㼟㼠㼛㼞㼍㼠㼕㼛㼚㻌㼏㼞㼛㼟㼟㻌㼟㼑㼏㼠㼕㼛㼚Fig.5 The restoration cross section of thedisaster point that we judged the slope of failure㼀㼔㼑㻌㼞㼑㼟㼠㼛㼞㼍㼠㼕㼛㼚㻌㼏㼞㼛㼟㼟㻌㼟㼑㼏㼠㼕㼛㼚Fig.6 The restoration cross section of the disasterpoint that we judged the natural hill of failure㼀㼔㼑㻌㼞㼑㼟㼠㼛㼞㼍㼠㼕㼛㼚㻌㼏㼞㼛㼟㼟㻌㼟㼑㼏㼠㼕㼛㼚

Surface protection method

Fig.7 The restoration cross section of the disasterpoint that we judged the surface of deform
"S-Incorrect͇ accounts for 80%. On the other hand,
as shown in figure 4(b), the restoration cost of"Incorrect" accounts for about 60% of the total, and"S-Incorrect" accounts for about 40%.
(3) Consideration of the characteristic of theslope disasterIn the case focused attention on the number ofslope disaster and restoration cost, a ratio of“Correct” and “S-Incorrect” change greatly. To
investigate of the above-mentioned cause, thenumber of 58 slope disasters are classified into
three kinds "Slope of failure", "Natural hill offailure", and "Surface deformation". The
classification of the slope disaster uses therestoration top view and the restoration crosssection of the damage point. We show below theexample of the restoration cross section of thedisaster spot that we spoke by the above. As forfigure 5, the slope of failure, figure 6 the natural hillof failure, figure 7 as surface of deform.
With the criterion mentioned above, we show theresult that classified in table 7. We show eachcriterion in table 8. In consequence, the numbers of
9 were slope of failure; the numbers of 11 were
natural hill of failure; the numbers of 38 weresurface deformation. Surface of deform the number
36 were “S-Incorrect”.
As shown in figure 8(a), show the ratio of theresult that classified of the slope disaster in the total
number of "S-Incorrect". In addition, figure 8(b)show the ratio of the restoration cost in the total
number of ͆S-Incorrect͇. In the case focused
attentions on the slope disaster number, surface ofdeform holds about 75% of the total. From this, it
became clear that a lot of surface of deform that therestoration cost was occurred by the NOTO
Peninsula earthquake. On the other hand, in thecase focus attention of a restoration cost, the surfaceof deform holds about 25% of the total.

Table.9 The criterion of the slope disaster
Slope of failure

Collapse soil is mentioned in the disaster point of the law side.

Natural hill of failure Collapse soil is mentioned in the disaster point of the natural hill.
Surface of deform

A restoration method of construction for the slope is carried out,
and there is not a mention of the collapse soil.

Slope of failure
13%
Natural hill of failure
13%

Surface ofdeform㻔㼍㻕㼀㼔㼑㻌㼞㼍㼠㼕㼛㻌㼛㼒㻌㼠㼔㼑㻌㼐㼍㼙㼍㼓㼑㻌㼚㼡㼙㼎㼑㼞

Surface ofdeform

Slope of failure
46%

Natural hill of failure29%㻔㼎㻕㼀㼔㼑㻌㼞㼍㼠㼕㼛㻌㼛㼒㻌㼠㼔㼑㻌㼞㼑㼟㼠㼛㼞㼍㼠㼕㼛㼚㻌㼏㼛㼟㼠Fig.8 The classification result of the slope
disaster in the "Select-Incorrect"
total.
The result clearly showed that NOTO Peninsula
earthquake damage was caused by out of theprevention inspection point. On the other hand, inthe case focused attention restoration cost of slope
disaster, relatively-massive damage place was madeappropriate judgments adequately in the casefocused attention restoration cost of slope disaster,
we consider the judgment method of the prevention
inspection an effective means of the NOTO
Peninsula earthquake.
However, in the case focused attention the numberof disaster, about 80 percent of all was damaged outof the prevention inspection point. And about 70%of disaster out of he prevention inspection point
was surface of deform. In the case focused thenumber of slope disaster, there is room for theimprovement at the surface of deform of theprevention inspection point.
REFERENCES
1) Ishikawa Prefecture㸸 2007 NOTO Peninsula
earthquake disaster record magazine㸪 p22㸪 2009.32) Road management technology center 㸸 The
manual of Road Disaster Prevention Inspection(heavy rain / heavy snow)㸪 2007.93) Japan Road Association㸸 The Road Earthquake
DisasterMeasure
Manual(preseismicCountermeasure)㸪 pp86-90㸪 2006.9

4. CONCLUSIONSIn this study, we examined the effectiveness of therisk assessment method of the prevention inspection
for the NOTO Peninsula earthquake damage in2007.
ձ About 80% of the total of the slope disaster are“S-Incorrect” that is a disaster out of aninspection point.
ղ In the case focused attention restoration cost ofslope disaster, “S-Incorrect” account for
approximately 40% of the total.
ճ In the case focused attention “S-Incorrect” ofslope disaster, surface of deform account for
approximately 70% of the total. Restoration
cost account for approximately 20% of the