THE WORST RECORDED NATURAL DISASTERS

USEFUL DATA ABOUT NATURAL DISASTERS                                   

                            

Earthquakes and volcanoes are among the most violent and unpredictable of all nature’s forces. High risk areas are along plate margins and coastlines. Some of to-day’s largest cities, including Tokyo, Los Angels and Mexico City have been built in these dangerous zones.

Facts and Figures:

• The largest earthquake ever was recorded off the coast of Chile on May 22, 1960. It measured 9.5 on the Richter scale.
• The Montagua earthquake in Guatamala in 1976 made more than one million people homeless. It also caused US $ 1.25 billion worth of damages.
• The largest volcanic eruption ever recorded was Krakata in Indonesia in 1883. The blast was heard 4635 kms. away and the collapse of the volcano caused 150 m waves in the nearby Sunda Strait.
• The largest volcano eruption of the 20^th century in the USA was NOvarupta in Alaska in 1912. The eruption produced 21 sq, kms. of volcanic material.
• The largest death toll from a tsunami was on the most-hit island of Indonesia in December 2004. Over one lakh people got killed and several lakhs were rendered homeless.

Destructive Forces:

Avalanches, landslides, giant waves and violent weather have been the cause of terrible catastrophes. As our understanding of these and other dangerous natural phenomena improves so does our ability to predict them and take measures to minimize the destruction they cause.

Guarding against earthquakes and volcanoes:

01.  Earth movements are monitored globally using instuments called seismometers. These pick up the minor vibrations which often preced major earthquake.

02.  Volcanoes often ‘bulge’ before an eruption as magma slowly rises in to them. Tiltmeters placed on a volcano can measure this and warn of an impeding eruption.

03.  Modern buildings are designed to withstand shocks in locations that are susceptible to earthquakes.

04.  Emergency evacuation plans have been put in place by countries most at risk particularly in Europe, the USA and Japan.

Avalanches and Land Slides:

Avalanches and Land Slides are the rapid mass movement of either snow and ice or earth under gravity. They are triggered by a number of factors.

• Weight: A heavy snowfall can provide enough extra weight to destabilize a sloping snowfield causing it to slide downhill, often taking rocks and trees with it.
• Water: Excessive rainfall or seeping ground water can destabilize and lubricate soil on a slope causing it to slide.
• Earthquakes: The vibrations from earthquake can destabilize both earth and snow causing landslides and avalanches.
• Noise: Vibrations caused by loud noises can trigger avalanches. Gunfire in the European Alps during the first World War is known to hasve caused several avalanches.
• Explosion: Avalanches can also be started by explosions in many places where avalanches are a threat, they are set off artificially by causing controlled explosions.
• Volcanoes: Volcanic eruptions are often associated with landslides and lahars. Lahars are mud flows caused when water from a crater lake or melted snow from the summit and sides of an erupting volcano, mixes with ash and slides downhill.
• Tsunami: The devastation tsunami can cause is legendary. Tsunami monitoring stations have been established in the Pacific since 1949. Although these provide an early warning system, there is little defensive action that can be taken other than evacuation.
• Storms: A storm is a violent disturbance in the atmosphere with wind speeds of 90 km/hr or higher- force 10 or above on the Beaufort scale. There are about 1600 storms taking place around the world at any one time,

Worldwide danger zones: Severe storms occur most frequently around Antarctica and the North Pole. However because of their remoteness these are rarely a danger to large number of people. The majority of truly devastating storms occur in the tropics, within about 23 degrees either side of the equator. This area includes densely populated cities and countries. Storms have different names, like hurricanes, cyclones, typhoons, depending upon their locations.

Floods: Floods can be caused by high tides, tsunamis or heavy rainfall. River floods can be exacerbated by deforestation upstream. This is the principal cause of the floods that have devastated Bangladesh in recent decades.

Facts and Figures:

• The most rain recorded over 24 hours was 187 cms. On the island of Reunion in the Indian Ocean in March 1962.
• A water spout ( a whirlwind that sucks up water ) struck the leading boats in the 2001 Sydeny to Hobart Yacht race.
• The longest lightening flash on record measured 30 kms.
• The most people killed by a single lightening flash was 81 passengers of a jet that crashed after being struck on December 8, 1963 above Maryland, USA.
• The most people killed by hailstorms was 246 in a storm in the city of Muradabad, India on April 20, 1988.
• Australian meteorologist Clement L. Wragg introduced naming of hurricanes in 1887.
• Recent hurricane that struck east coast of USA in August 2011 had a devastating effect on the people living there.
• Incidence of frequent shocks of earthquakes in last week of August in our region has caused alarm all around.