Civil Engineering Reference
In-Depth Information
and has social cohesion. Widespread damage can have a substantial long-
lasting social, economic and cultural impact on the well-being and vitality
of a city and nation. Some recent examples are the earthquakes in the three
continents:
2009 L'Aquila earthquake in Italy (Europe);
2011 Christchurch earthquake in New Zealand (Oceania);
2011 Tohoku earthquake in Japan (Asia).
The 2011 Tohoku Earthquake caused $319 billion in direct damage and
$619 billion costs of recovery and other indirect losses, but mostly it showed
that post-earthquake evaluation needs improvements in order to be more
systematic, accurate and quicker trying to allocate resources and personnel
involved in the recovery process effi ciently. However a magnitude 9.0 event
is very large and it is not possible to avoid chaos in the response. Overall
the military forces were very effective in rescue activities, as were the emer-
gency authorities.
The 2011 Christchurch earthquake (EERI, 2011; Muir-Wood, 2012) in
New Zealand will be remembered for the effect of very close main shocks
and numerous aftershocks. New unmapped faults were found during these
events which is a quite common characteristic of every earthquake. The
presence of all these uncertainties has shown the current limitations of the
Uniform Hazard Spectrum (UHS) which is built using known seismogenic
earthquake sources defi ned in terms of location, geometry and character-
istics which are time and spatially independent. A
M
w
6.3 earthquake after-
shock was registered near Christchurch, New Zealand, on Monday, February
21 (UTC), 2011, being triggered 6 months after a
M
w
7.0 earthquake struck
the South Island of New Zealand. Obviously these two events cannot be
considered as time and spatially independent, therefore recent develop-
ments (Yeo and Cornell, 2009) are able to incorporate aftershocks effects
in probalistic seismic hazard analysis (PSHA), but these methodologies
have not been incorporated in the assessment of the UHS.
The 2009 L'Aquila earthquake in Italy showed a well-organized emer-
gency response in the short term, but the long-term reconstruction phase is
showing poor performance of decision makers and politicians who are also
an essential part of the recovery process. It also pointed out the necessity
to rehabilitate old masonry buildings using traditional retrofi t techniques
which performed pretty well when properly designed and installed, reduc-
ing building vulnerability (Cimellaro
et al.
, 2010a).
After all these recent extreme events, the international community has
become aware that resilience is the key to describe earthquake engineering
performance. Disaster resilience is often divided between technological
units and social systems (Bruneau
et al.
, 2003). On a small scale, when consid-
ering critical infrastructure, the focus is mainly on technological aspects. On
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