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

Landslides or flooding disasters are closely linked to rapid and unchecked urbanization that
forces low-income families to settle on the slopes of steep hillsides or ravines, or along the
banks of flood-prone rivers.
Famines can be closely linked to shortages of purchasing power caused by rural unemployment
or a sudden influx of refugees into a country from a strife-torn neighboring country.
High numbers of deaths accompanying earthquakes almost always result from structural
collapse of poor, low-cost houses.
In other disasters, such as cyclones and tsunamis, humans can increase their vulnerability by
removing bits of their natural environment that may act as buffers to these extreme natural
forces. Such acts include destroying reefs, cutting natural wind breaks and clearing inland
forests.
The poor countries that suffer the worst disasters are the same countries in which
environmental degradation is proceeding most rapidly. Countries with severe deforestation,
erosion, overcultivation and overgrazing tend to be hardest hit by disasters. 4
Therefore, it can be said that nature causes extreme events (called “hazards” when they
threaten people), but people create disasters by:
• making faulty assessments of natural hazard risks
• undermining the resilience of impacted natural and social systems, and
• failing to practice appropriate protective measures.
Natural hazards are agents or trigger mechanisms that can come into contact with a vulnerable
human condition to result in a disaster.
Classifications of Disasters
Hazards and the disasters they cause are classified as rapid onset or cataclysmic, and longterm
or continuing. In a cataclysmic disaster, one large-scale event causes most of the damage
and destruction. Following this event, there may be a tremendous amount of suffering and
chaos, but things soon begin to improve. In a long-term, continuing disaster, the situation after
the event remains constant or may even deteriorate as time passes. Cataclysmic disasters
include earthquakes, volcanic eruptions, cyclonic storms, and floods. Continuing natural
disasters include droughts, crop failures, and environmental degradation such as deforestation
and desertification. The damaged area in a cataclysmic disaster is usually relatively small,
while the area affected in a continuing disaster may be extremely large.
Cataclysmic disasters destroy buildings and entire human settlements. Loss of life is sudden
and therefore dramatic. In terms of food and food distribution, cataclysmic disasters are
normally more disruptive than destructive. For example, they may disrupt the transport and
marketing systems. They can disrupt or damage irrigation systems and, to a limited extent, they
may destroy food supplies. But the extent of destruction depends on the season, the location of
the disaster, and the total area affected. On the other hand, while continuing disasters disrupt
transportation and distribution networks, they can also bring them to a complete halt and
ultimately destroy the system itself. 5