Resilient Cities: Coping With Natural Hazards - Theme Cities: Solutions for Urban Problems - page 310

9﻽2 Natural Hazard Variations

9.2.1 Types of Hazards

We live in a world in which our regular life and activities generally function within
the normal range of both seasonal climate changes and small-scale geophysical pro-
cesses. But we are in a period in which the old climate averages based on records
of the previous 30 years are being adjusted to new normals to take into account the
effect of an average global warming of at least 0.8 ﾰC degrees since 1880. Accord-
ing to the 2012 reports of the U.S. National Oceanic and Atmospheric Administra-
tion (NOAA 2012 ) temperatures have been rising above the long term average for
the 36th year in a row, although the last decade has seen a reduction in the rate of
growth, primarily because of the oceanic absorption of the extra heat. In addition,
some natural events are occurring with much higher magnitudes and in new loca-
tions—effects often not seen for generations—that involve the input of sufficiently
large concentrations of energy and materials into the environment to cause threats
and harm to humans and their assets. For example, it has been revealed that the av-
erage latitude at which tropical cyclones reached their maximum intensity in each
year over the last 30 years had moved polewards by 53 and 62 km per decade in
the north and southern hemispheres respectively, paralleling the shift of the tropi-
cal zone expansion (Kossin et al. 2014 ). Given the coastal location of many major
big cities this trend will make more liable to larger storms in the future. This means
that many buildings and infrastructures will have to be moved or built stronger to
withstand the emerging climate regimes. Significant losses of life and environmen-
tal degradation also come from unintended consequences of direct human actions,
such as various industrial accidents, while indirect human influences can also cause
disasters and may help exacerbate the effects of some of the physical hazards. Al-
though these potential hazards to cities can be classified in many ways, they are
basically of five broad types shown in Table 9.1 .
It is impossible for a single chapter to cover all of these issues in any detail, so the
focus of this discussion is upon the consequences of the first three of these types of
natural or physical hazards and the emerging range of risk management procedures

Table 9.1 Types of hazards affecting settlements
Main origins

Major hazard examples

1. Geophysical Earthquakes, volcanoes, landslips, avalanches and mudslides, extra-terrestrial-

meteorites etc.

2. Climate extreme heat, cold or drought, intense precipitation (rain, hail, snow, ice), fog,

lightning, storms and winds (hurricanes, typhoons, tornadoes, local winds).

4. Biological Diseases, toxic plants, landscape fires.

5. Human a) Direct: transport accidents, industrial plant failures, toxic material spills,

building and infrastructure decay and collapse, fires, wars.
b) Influences: pollution, land-sea degradation, climate changes.