Natural Hazards: Causes and Effects - Disaster Management Center ...

If the number of “people affected” actually included the people who pay tax or otherwise
contribute to the disaster response, then the number of people affected would be far greater.
Not included in the above statistics is the growing threat from technological hazards such as
liquid nitrogen gas, cyanide, nuclear reactors, etc. Nor is the disaster created by civil strife
treated here. A discussion of these dangers is beyond the scope of this course.
What Are Disasters?
Natural hazards such as earthquakes, hurricanes, floods, and droughts spring to mind when the
word “disaster” is mentioned. But a disaster should be defined on the basis of its human
consequences, not on the phenomenon that caused it. An earthquake, for example, is simply
an event in nature. Even a very strong one is not a disaster unless it causes injury or destroys
property. Thus an earthquake occurring in an uninhabited area (as do scores of major tremors
each month) is only of scientific interest and is not considered a disaster.
When a natural event does affect a human settlement, the result may still not be a major
disaster. Consider the earthquake that struck San Fernando, California, in 1971. The quake
registered 6.4 on the Richter scale, yet the region around San Fernando Valley (with a
population of over seven million people) suffered only minor damage and 58 deaths. Two years
later, though, an earthquake of a magnitude of 6.2 struck Managua, Nicaragua, and reduced the
center of the city to rubble, killing an estimated 6,000 people. 3
A disaster can be more precisely defined as an occurrence of widespread severe damage,
injury, or loss of life or property with which a community cannot cope and during which the
society undergoes severe disruption.
While some developed nations may be as prone to disasters as poor nations, the people of
wealthier nations are not as vulnerable to disasters; they do not die in as large numbers nor
does their environment collapse as easily. Both Tokyo, Japan, and Managua, Nicaragua, are
prone to earthquakes. But the people of Tokyo are far less vulnerable to injury by earthquake
because Tokyo has strictly enforced building codes, zoning regulations and earthquake training
and communications systems. In Managua, there are still many people living in top-heavy mud
houses on hillsides. They are vulnerable.
This difference is shown by a list of disaster events and fatalities over 1960-81 (Fig. 1.4).
• Japan suffered 43 earthquakes and other disasters and lost 2,700 people: 63 deaths per
disaster.
• Peru suffered 31 disasters with 91,000 dead, the vase majority lost in the single event of the
1970 earthquake.
Analysis of Fig. 1.4 shows that the vast majority of the deaths occurred in just two catastrophic
events, the 1970 Bangladesh cyclone killing nearly 500,000 and the Tangshan, China,
earthquake in 1976, killing over 240,000 people.
Rapid population growth, urban migration, inequitable patterns of land ownership, lack of
education, subsistence agriculture on marginal lands, etc. lead to vulnerable conditions such as
unsafe siting of buildings and settlements, unsafe homes, malnutrition, unemployment and
underemployment, illiteracy, etc. The poor within the poor countries are the most vulnerable.