Research Trends and Results

Efforts to Minimize Damage to Sewerage
Infrastructure in the Event of a Major Earthquake
OGAWA Fumiaki, Head; FUKATANI Wataru, Senior Researcher; MATSUHASHI Manabu, Researcher
Wastewater System Division, Water Quality Control Department
Keywords: sewerage pipeline, major earthquake, database, disaster support system
1. Introduction
In the Cabinet Office Central Disaster Prevention
Council, there is concern about a massive earthquake that
may occur in the Nankai Trough or directly under
Metropolitan Tokyo. Should such an earthquake occur,sewer pipelines, one of the critical lifelines, are expected
to suffer serious damage. It is, therefore, urgently
required to establish pre- and post-earthquake measures
to minimize damage, ensure toilet functions afterearthquake and preserve water quality in public waters.
Since damage simulations of higher accuracy are required
to implement effective measures, it is effective to analyze
and utilize damage trends based on data on pipeline
damage caused by past earthquakes including the Great
East Japan Earthquake.
NILIM is organizing data on pipeline damage causedby past earthquakes in a unitifed format in order to utilize
the data for simulating damage to sewer pipeline
infrastructure in the event of a massive earthquake suchas a Nankai Trough Massive Earthquake. Using this data,
NILIM is performing simulations of damage to sewer
pipeline infrastructure in the event of a massive Nankai
Trough Earthquake, studying disaster support systems
and effective earthquake-proofing for infrastructure, andevaluating priorities in disaster mitigation measures.
2. Establishment of a database of damage
information on sewer pipeline infrastructure
Since earthquake-proofing of existing infrastructure
requires a lot of money and time, it is necessary to
promote earthquake-proofing efficiently and effectively
by estimating areas prone to damage in advance,
determining priorities amongst earthquake proofing
measures, and focusing investment in areas of highpriority.
In prioritizing earthquake-proof measures, it isnecessary to consider the probability of damage to any
sewer system and the social impact if the seweragesystem is damaged. To consider the probability ofdamage, it is effective to analyze damage trends, but
information on past damage is not well organized. NILIM
is collecting information on damage to sewerage systems
available since the 2000 Western Tottori Earthquake, tocreate a database in a unified format.
In fiscal 2013, data from about 130 local governments
damaged by the Great East Japan Earthquake wascollected to organize the data on the specifications ofsewer pipeline infrastructure (pipe type, pipe diameter,year of installation, etc.) and level of damage thereto,

damage information including the number of cases ofmanhole liquefaction, ground information including thenature of soil, N-value, etc., and turbulence information
including measured seismic intensity, etc.
3. Simulation of damage to sewer pipeline
infrastructure in the event of a massive Nankai
Trough Earthquake and study on support systems
A massive Nankai Trough earthquake, which is expected
to occur, is estimated to cause wide-spread damage
across prefectures and Regional Development Bureaus.
Support from national and local governments is essential
to minimize damage to sewer pipeline infrastructure andrestore functions promptly. It is, therefore, important tostudy in advance necessary support systems, rules ofsupport, etc. based on damage simulations.
Based on the seismic intensity and flooding fromtsunamis assumed by the Central Disaster Prevention
Council for a massive Nankai Trough Earthquake,
NILIM is simulating damage to sewer pipeline
infrastructure and studying necessary support systems.
In the future, after analyzing the factors that greatly affectdamage quantity, such as earthquake-proofing ofinfrastructure and ground conditions, we are going toimprove the accuracy of damage simulations and study
technologies for immediate damage estimation.
4. Conclusions
Since the Great East Japan Earthquake, local
governments throughout the country are reviewing theirdisaster prevention plans and earthquake-proofing
infrastructure. There are various constraints on such
efforts, but since it is essential in the future to simulate
damage at low cost and to a high degree of accuracy, andcarry out measures efficiently and effectively, NILIM
will also advance research relating to the issues.
Kushiro-oki Earthquake
Southern Hyogo Prefecture
Earthquake

infrastructure
specifications

Ground conditions

Mid Niigata Prefecture
Earthquake2011 Tohoku Offshore
Earthquake

Seismic
characteristic

Pipe type

Pipediameter

PL value Soil property

Seismic
intensity

Covering Pipe age

Ground water

Acceleration

Figure: Image of Database

Damageclassification