Messages from Departments and Centers of NILIM

How are we Restructuring Fragile Cities Faced withEarthquake Disasters?
KANEKO Hiroshi, Director
Urban Planning Department(Key words)

Tsunami disaster prevention urban development, Countermeasures against liquefaction of residential

land,, Fire evacuation simulator
1. Foreword
Three years already have passed since the Great East
Japan Earthquake, which brought on unprecedented
damages, and the Act on Regional Development in
Tsunami Disaster came into effect in December 2011,
and a damage projection of a major Nankai Troughearthquake was publicized in fiscal 2012 from theCabinet Office, predicting tremendous damages byearthquake tsunami in the coastal cities.
Furthermore, a damage projection of a Tokyo-area
epicentral earthquake was publicized in December lastyear from the Cabinet Office, estimating a magnitude
7-class earthquake occurring with a probability of 70%
within 30 years, predicting a death toll of 23,000, totalcollapse of 175,000 buildings and 415,000 to be burnt to
the ground in the worst case.
In Japan’s cities in which population and industries areconcentrated, the enhancement in preventive strengthagainst such earthquake disasters is an urgent issue;
though a variety of disaster preventive countermeasures
are constantly prepared, in order to enhance the cities’
disaster prevention capabilities, further effective
countermeasures must be taken expeditiously.
2. Current tasks and direction to be tackled byresearch and development.
Meanwhile, due to the existence of the following tasks toproceed with urban disaster prevention measures, R&D
corresponding to these has been required as well as theactivation of new scientific knowledge in technologicaldevelopment.
(1) A big change in social economy and diversification in
urban disasters: From local cities faced with population
decline to mega-cities complicated by high density, avariety of urban disasters have been presumed, undersuch circumstances a stance to always verify as towhether or not there are risks of new crucial disasterphenomena occurring is constantly required.
(2) Restriction of time and budget in disaster prevention
measures: Despite how much time remains allotted until
the occurrence of a huge scale earthquake, and in addition,with the rigorous budget restrictions, the key point is towhat extent fragile areas can be fixed in place andconcentrated and effective disaster preventive measures
can be prepared.
(3) Interpretation is easy to understand for damage
forecast and disaster preventive effect: In order to urge
cities disaster prevention measures, the understanding ofpeople involved such as regional inhabitants isindispensable, and from preconditioned damage forecasts
to content of disaster preventive measures, and in regard
to those effects, tools capable of explaining matters
plainly is important.
(4) Limitations of damage forecast simulator andimprovement efforts: Urban disasters cannot be
reproduced and verified beforehand, inasmuch as there is
no alternative but to depend on complementary
experiments and forecasts by simulators based ondamaged scenarios in the past, as well as endeavoring to
improve simulators through experiments or the like for
newly presumed disaster phenomena, not only by
upgrading but also accelerated dissemination bysimplification is necessary.
(5) A variety of countermeasures of hard/soft and urban
restructuring: From hard countermeasures improvement
for infrastructures or the like and reconstruction
promotion for decrepit buildings to soft countermeasures
such as smooth guidance for evacuees, urban
reconstruction countermeasures, disaster prevention
countermeasures are required to effectively be carried out
among measures for urban reconstruction.
I will introduce the content of research currently being
carried out in the Urban Planning Division and visions forthe future in the following.
3. Tsunami prevention urban construction anddevelopment for assistance tools for liquefaction
countermeasures
In the Great East Japan Earthquake, in the damaged
coastal cities, evacuation against tsunami, security offunctions for disaster prevention preparedness facilities, abroad array of fragility of liquefaction or the like wasclarified. For this reason, coastal cities nationwide aredeliberating preparedness against these problems, and toreflect to the project of configuring tsunami prevention
city has become imperative.
Accordingly, in a study on disaster prevention structuringassistance technology, we have been engaging withearthquake proof safety for important lodgment facilities
and resilience of lifelines, substitution by other facilities
and the development of methods for ensuring ofcooperative network.
In addition, in the onslaught of a tsunami, adding in thecollapse of buildings and effects of fires, in order forinhabitant including vulnerable people such as the elderly
to smoothly and safely evacuate, a case study is being
implemented in the multiple coastal cities facing theNankai Trough, as well as developing tsunami evacuation
simulators by road and vehicles. Hereafter, we will verify
the efficiency of simulators, and reflecting this in tsunami
disaster prevention urban creation plan formulation ineach city and utilization in the urban area can beexpected.
Furthermore, based on the liquefaction damage occurringin the Great East Japan Earthquake, in addition tocalculation software capable of judging easily in regard topossibility of liquefaction damages from groundconditions or the like, as a countermeasure againstliquefaction for housing land, we will develop acalculation software capable of judging an effect inconformity with the ground condition of undergroundwater level declining construction method and gridunderground wall construction method to be publicized.
By utilizing these, in addition to configuration ofliquefaction risk degree maps as a pre-earthquake
countermeasure, as a post-earthquake countermeasure,configuration of an effective liquefaction countermeasure
cam be expected.
4. Development of a bloc performance forecast
evaluation tool for improvement promotion ofcongested urban districts
In case of large scale earthquakes or the like, in view ofpresuming tremendous damage of congested urban
districts, the housing life basic plan (nationwide plan)
aims to mostly eliminate “conspicuously dangerous
congested urban districts” of about 6,000ha (for fiscal2012) in fiscal 2020.
At the same time, since roads in congested urban areas
are narrow and residential land is also narrow and small
and due to the difficulty to adapt to the restrictions of theBuilding Standards Law, cases of difficulty inreconstruction are many, and there are problems withdifficulty in the replacement construction of decrepit
timber housing due to high risks of fire spreading andcollapse.
In this regard, in the Development of CoordinatedReplacement Building Rule Formulation Technology in
the Congested Urban Districts, we investigated theenvironmental level of existing congested urban districts,
and are currently proposing a tool for calculating thecondition of sun shadow hours prescribed in the BuildingStandards Law and daylight conditions in addition toevaluation tools for safety, using fire and evacuation

simulations based on buildings in urban districts andconditions or the like of roads.
Utilizing these research results, we are proceeding withdeliberations for guidelines of coordinated replacementbuilding in the congested urban districts; we have alreadyheld repeated hearings targeting academic experts andlocal public authorities, when using preferential measures
such as consolidated building design system, and will
prepare an evaluation tool to compare how far the bloc
performance varies, advancing deliberations withreference to conditions to carry out designated permission
in the Building Standards Law.
According to this research, the coordinated replacementbuildings in the congested urban districts willappropriately be carried out utilizing the designatedmethod of the Building Standards Law, and thepromotion of the disaster prevention measure and theenhancement of living environment in regular life will beexpected.
5. Future efforts for the improvement of fragile urban
structure
Furthermore, on the assumption of changes insituations in the urban districts and complexity inescaping in evacuation actions in case of disasters, wewill verify the scope of fragile parts of cities in view ofdisaster prevention, stemming conditions, the degree ofeffects or the like and a study on fragile part of cities
against fire in the urban districts in earthquakes andevaluations for disaster preventive effects, which will
implement evaluation and verification for disasterprevention countermeasures based on those, to be carriedout in three years from the next fiscal year.
This study corroborates the features of new materials
in fire in urban districts by fire experiment or the like, as
well as reflecting to a fire evacuation simulators, carryingout a case study reflecting the actual state of fragile
congested urban districts, effects of fire on the decrepit
congested land with wooden houses and effects of fire on
sloping land, complexity situations in evacuation and therelevancy to disaster prevention effects for those, we havemade to develop a method for evaluation/verification in
respect to disaster prevention effects for those.
Regarding measures for restructuring of cities in eachcity and responding to various problems, we would liketo actively engage with research and development (R&D),
so as for fire prevention measures to be promoted with afocus placed on priority and effectiveness.