NATURAL DISASTERS

INTRODUCTION

Nature around us is a source of life. The sun makes flowers and trees grow, soil along the river, or at the base of volcanoes, is fertile and good for crops. But too much sun or rain is bad for plants, and floods or volcano eruptions can destroy whole towns.

Earthquakes, floods, fires, volcanic eruptions, tropical storms, landslides, drought, are part of nature, like sun and rain. These events affect almost every part of the earth. Long ago, people only had folk tales to explain these events. Today, science and history help us understand more about them. But we still have natural disasters.

Extreme natural events may cause disasters, but some events that seem natural are caused by people. Too much or too little rain may cause floods or drought. But floods and drought can also happen because we don’t take proper care of the earth. If we destroy parts of nature like cut trees faster than the nature can replace them, the soil becomes poor and hard, and won´t absorb water properly. If we destroy parts of nature like coral reefs, forest, or fragile mountains plants, we take away natural barriers that protect us from tsunamis, drought, landslides or other events.

1. What is an environmental emergency?

Environmental emergencies are defined as sudden-onset disasters or accidents resulting from natural, technological or human-induced factors, or a combination of these, that causes or threatens to cause severe environmental damage as well as loss of human lives and property. The terms includes secondary consequences from natural disasters such as earthquakes, storms, floods, volcanic eruptions, tsunamis, wild land fires, hurricane, droughts, tornado o twister, avalanches, etc. and man-made disasters such as industrial accidents, transport accidents, chemical spills, oil spills and a multitude of other types of emergencies.

2. Types of emergencies

a. Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. At the Earth's surface, earthquakes manifest themselves by vibration, shaking and sometimes displacement of the ground. The vibrations may vary in magnitude. Earthquakes are caused mostly by slippage within geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. The underground point of origin of the earthquake is called the focus. The point directly above the focus on the surface is called the epicenter. Earthquakes by themselves rarely kill people or wildlife. It is usually the secondary events that they trigger, such as building collapse, fires, tsunamis (seismic sea waves) and volcanoes, that are actually the human disaster. Many of these could possibly be avoided by better construction, safety systems, early warning and planning. Some of the most significant earthquakes in recent times include: The 2004 Indian Ocean earthquake, the third largest earthquake recorded in history,registering amoment magnitude of 9.1-9.3. The huge tsunamis triggered by this earthquake killed at least 229,000 people.

• The 2011 Tōhoku earthquake and tsunami registered a moment magnitude of 9.0. The death toll from the earthquake and tsunami is over 13,000, and over 12,000 people are still missing.

• The 8.8 magnitude February 27, 2010 Chile earthquake and tsunami cost 525 lives.[7]

• The 7.9 magnitude May 12, 2008 Sichuan earthquake in Sichuan Province, China. Death toll at over 61,150 as of May 27, 2008.

• The 7.7 magnitude July 2006 Java earthquake, which also triggered tsunamis.

b. Volcanic eruption

Volcanoes can cause widespread destruction and consequent disaster in several ways. The effects include the volcanic eruption itself that may cause harm following the explosion of the volcano or the fall of rock. Second, lava may be produced during the eruption of a volcano. As it leaves the volcano, the lava destroys many buildings and plants it encounters. Third, volcanic ash generally meaning the cooled ash - may form a cloud, and settle thickly in nearby locations. When mixed with water this forms a concrete-like material. In sufficient quantity ash may cause roofs to collapse under its weight but even small quantities will harm humans if inhaled. Since the ash has the consistency of ground glass it causes abrasion damage to moving parts such as engines. The main killer of humans in the immediate surroundings of a volcanic eruption is the pyroclastic flows, which consist of a cloud of hot volcanic ash which builds up in the air above the volcano and rushes down the slopes when the eruption no longer supports the lifting of the gases. It is believed that Pompeiiwas destroyed by a pyroclastic flow. A lahar is a volcanic mudflow or landslide. The 1953 Tangiwai disaster was caused by a lahar, as was the 1985 Armero tragedy in which the town of Armero was buried and an estimated 23,000 people were killed.

c. Hydrological disasters

It is a violent, sudden and destructive change either in quality of earth's water or in distribution or movement of water on land below the surface or in atmosphere.

• Flood

A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Flooding may result from the volume of water within a body of water, such as a riveror lake, which overflows or breaks levees, with the result that some of the water escapes its usual boundaries. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, it is not a significant flood unless the water covers land used by man like a village, city or other inhabited area, roads, expanses of farmland, etc.

Some of the most notable floods include:

• The 1998 Yangtze River Floods, in China, left 14 million people homeless.

• The 2000 Mozambique flood covered much of the country for three weeks, resulting in thousands of deaths, and leaving the country devastated for years afterward.

• The 2005 Mumbai floods which killed 1094 people.

• The 2010 Pakistan floods, damaged crops and infrastructure, claiming many lives.

• Tsunami

Tsunamis can be caused by undersea earthquakes as the one caused by the 2004 Indian Ocean Earthquake, or by landslides such as the one which occurred at Lituya Bay, Alaska.

• The 2004 Indian Ocean Earthquake created the Boxing Day Tsunami.

• On March 11, 2011, a tsunami occurred near Fukushima, Japan and spread through the Pacific.

d. Meteorological

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