Earthquake risk management of civil infrastructure: integrating soft and hard risks - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 226

safety specialists manage the known health and safety risks well and quality
managers manage the known and recognised processes well. Nevertheless
within specialisms a range of techniques may be used to assess different
aspects of risk which are diffi cult to integrate. For example, structural engi-
neers not only have new powerful computational tools but there are also
many new and different challenges such as terrorist attack and the impact
of climate change. The net result is that even in successful projects and
companies, major problems seem to arise in the gaps between specialisms
resulting in unknown and unintended complications, such as cost and time
overruns and consequent quality problems. Sometimes even processes for
which no one is directly responsible happen and hence are not properly
controlled. Then there are surprises from previously unknown, unexpected
and unforeseen events.
In this chapter we will address the problem of how we can better facilitate
well-balanced decisions to manage all risks to minimise unintended harmful
consequences. Risk is particularly pertinent to people living in active seismic
zones. At all too frequent intervals, TV pictures of earthquake damage to
buildings, bridges and other infrastructures are beamed around the world.
Similarly sized earthquakes can have very different impacts in different
countries depending on the degree of engineering input into the design and
construction of the facilities. For example, in 2010 similarly sized earth-
quakes in Haiti and New Zealand produced very different consequences.
However in early 2011 Christchurch in New Zealand was hit by a less severe
earthquake in terms of released energy but one that caused more loss of
life and damage. In March 2011 a large earthquake, consequent tsunami
and damage to a nuclear power station, caused considerable loss of life and
damage to large parts of the infrastructure of one of the most prepared
nations in the world: Japan. It is crucial therefore to identify structures,
groups of structural types and whole regions or countries where vulnerabil-
ity to earthquakes is unacceptably high.
A key diffi culty is how decision makers integrate information from many
disparate sources, including different worldviews with different theoretical
or calculational models, to manage risks. Risks are also communicated to a
wide variety of people in many different and potentially confusing ways.
For example rather vague descriptions such as moderate, high or very high
may refer to the return period or the level of damage, whereas evidently
statistical descriptors, such as 1 in 100 years, may leave us unclear about the
level of damage.

9.2 Managing technical risks to structures

Advice to practical engineers about the risks to structures in seismic zones
usually focuses on fi ve technical areas (e.g. Booth and Key, 2006; Gibbs,