Resilient Cities: Coping With Natural Hazards - Theme Cities: Solutions for Urban Problems - page 317

what really are the fragile electronic linkages that connect the contemporary world
in so many ways. Yet despite all these examples of destructive effects it is worth
remembering that some of these extreme natural events create longer term positives ,
such as the annual river flooding that deposits silt in flood plains and increases their
fertility, as seen in the Nile and other major river valleys. With the social organiza-
tion that provided the catalyst to organize the surplus of the greater productivity
from such lands, these areas developed many of the world's first urban civilizations.

9﻽4 Hazard Risks and Human Activities

At first sight it would appear that the loss of human life and destruction of prop-
erty and infra-structure from one or more of these natural hazards is a product of
these environmental events alone. However there can be no doubt that the scale of
the disasters from natural events has been actively increased by human activity, as
stressed by many texts on environmental hazards (Smith and Petley 2009 ) and such
reports as Rethinking Disasters (Bray et al. 2008 ) or Arup's ( 2011 ) report for the
Red Cross. Several factors contribute to this conclusion. The most obvious is an
increasing population size and areal spread of settlements, which provides a bigger
target area for natural hazards, given the limited spatial incidence of at least some
of these events. Their wealth often makes losses higher. In addition, location factors
are involved. For example, many settlements have been built or extended on flood
plains or seashores, ignoring the risk of exceptional floods, tides or storm surges and
the sewer back-ups that occur. Although these problems exist in the developed world
especially on the low over-built South Florida coast, it is in the developing countries
that some of the greatest risks occur. For example, many large cities in lowland
basins, such as Jakarta, are increasingly prone to flooding, as seen by the 2002 and
2007 floods, displacing 365 and 450,000 people respectively—which in the latter
case led to three-fifths of the city being under water for several days. Part of the de-
struction is due to greater cyclone incidence, but as much is due to the result of more
intense human activity in its site. It has been estimated that the area is sinking ten
times as fast as the current sea level rise, due to ground water extraction, compaction
from high rise buildings, and the over-concreting of lands (Jha et al. 2012 ), while lo-
cal wetlands have been built over. However Jakarta's failure to dredge its dozen riv-
ers and canals—which have silted and receive a third of the garbage output—have
contributed substantially to the problem, although the World Bank and the Indonesia
government are now embarked on major waterway maintenance and rehabilitation
projects. Similar problems are expected in many other coastal Asian megacities
(Adikrai et al. 2010 ). The floods around Bangkok in 2011 inundated many of the
area's industrial parks, resulting in $46 billion estimated losses in this 1 year .
In the context of earthquake damage it is worth noting the locational differenc-
es in destruction in areas of different material. Buildings on clay, sand or silt on
shorelines suffer more from earthquakes than those on rock. The reason is that the
earthquake-shaking tremors are amplified in such sediments and if the sediments