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...one before it. The period between waves is 10 to 30 minutes. This usually gives people ample time to escape to high ground after the first wave. Most tsunamis originate along the Ring of Fire. The Ring of Fire is a area of volcanoes and seismic activity 24,000 mi long. It encircles the Pacific Ocean. Since the year 1819, more than 40 tsunamis have struck the Hawaiian Islands. A tsunami warning system has been developed in areas such as Hawaii, where many devastating tidal waves occur. Hawaii, the highest risk area, averages one tsunami every year with a damaging occurrence every 7 years. Alaska, also at high risk, averages a tsunami every 1.75 years and a damaging event every 7 years. The warnings are provided by seismograph records. Seismographs help determine the location of where a submarine earthquake occured. These earthquakes usually originate in one of the deep trenches in the Pacific Ocean floor. One of the largest and most destructive tsunamis ever recorded traveled at least half way around the world in 1883 after the collapse of Krakatoa, a volcano in Indonesia. Waves up to 100 ft. high caused great damage along the coast of Sumatra. In 1964, an Alaskan earthquake generated a tsunami with waves between 10 and 20 feet high along parts of the California, Oregon, and Washington coasts. This tsunami caused more than $84 million in damage in Alaska and 123 fatalities in Alaska, Oregon, and California. Although tsunamis are rare along the Atlantic coastline, a severe earthquake on November 18, 1929, in the Grand Banks of Newfoundland generated a tsunami that caused considerable damage and loss of lives at Placentia Bay, Newfoundland. In 1946, a tsunami with waves of 20 to 32 feet crashed into Hilo, Hawaii, flooding the downtown area and killing 159 people. The Tsunami Warning Centers in Honolulu, Hawaii, and Palmer, Alaska, monitor disturbances that trigger tsunamis. When a tsunamis is recorded, it is tracked and a tsunami warning is issued to the threatened area. Most deaths during a tsunami are a result of drowning. Associated risks include flooding, polluted water supplies, and damaged gas lines. Since 1945, more people have been killed as a result than as a direct result of an earthquake's groundshaking. Lightning Even today the phenomenon of lightning is still not fully understood. It is awesome and frightening to many and because of the mystery that surrounds it, several cultures have developed different beliefs about it. Some African cultures believe that when someone is hit by lightning that he/she was cursed even before the event. The Romans and Greeks believed that the gods were fighting and this was one of their weapons. Lightning kills and injures many people, starts thousands of forest fires, and causes millions of dollars in property damage every year. Lightning is characterized by the discharge of electricity between rain clouds or between a rain cloud and the earth. It is usually seen as an arc of extremely bright light which can be many kilometers in length, however, there are other forms as well. Accompanying the lightning is the giant roar of thunder. The thunder is caused by the expansion of air that has been heated by the lightning which then collides with cooler air, creating the sound of an explosion. Thunderstorms are the most common types of storms, and thunder itself, although frightening, is not dangerous. It is the lightning that causes the problems. Lightning and thunder occur together, however we hear the thunder after we see the lightning. Sound waves travel about one mile in five seconds, while light travels at more than 186,000 miles per second. Therefore, lightning is seen immediately when it occurs, and thunder is heard a little later. The different sounds of thunder (deep roar/loud crash) is caused by the different types of lightning, for example, the thunder that has the sharp crackle like sound is caused when the large trunk of lightning forks into many branches. Types of Lightning There are a variety of different forms of lightning. Also, observers see lightning differently depending on where they are situated. Major forms of lightning include forked lightning, streak lightning, ribbon lightning, and chain lightning. There are also rare forms of lightning such as ball lightning, red sprites, blue jets, and elves that have been documented. o Forked lightning is lightning in which visible branches are present. o Streak lightning is a bolt that appears to be a single arc shaped line. o Ribbon lightning is viewed as parallel streaks of light. It is caused when winds separate the strokes of the bolt. o Chain lightning (also called Bead lightning) is characterized by a bolt that breaks into dotted lines as it fades. o Ball lightning's appearance is that of a fiery glowing ball (usually in red, yellow, or orange) which floats several feet above the ground. It can be as big as a grapefruit in size. It has also been reported to have been floating within houses and barns. It is unknown why ball lightning occurs and what it is made of. o Red sprites are characterized as a dim, reddish-colored burst. They only last for a couple thousandth of a second and can be numerous kilometers wide. They appear suddenly, most likely more than one at a time, and rise up to 90 kilometers above the cloud layer. o Blue jets are cone-shaped bursts that spring forth from the center of a thunderstorm at speeds up to six thousand kilometers per hour. The rise up to 50 kilometers above the cloud tops and are brighter than red sprites. o Elves are bursts of light shaped like a doughnut or saucer. They are about four hundred kilometers wide and occur one hundred kilometers above the cloud tops. They last for less than one thousandth of a second and are theorized to be green in color. Safety Tips Since lightning can be very dangerous and it has killed and maimed many people, it is important for us to follow safety measures and protect ourselves and property. During a storm stay indoors, however if you are caught outside in a severe storm, never stand under any tall objects such as trees. It is better to lay down in an open field away from any surrounding tall objects. Avoid any large bodies of water and if you are swimming, leave the water immediately. Stay away from metal objects such as bicycles and tractors. Never play golf or go fishing during a storm. If your are outside playing any games with metal gear, be sure to take it off if a storm starts. If you are driving a car during a thunderstorm stay in the car as this is though to be a safe place, however avoid touching any metal in the car. Do not use the telephone since lightning might strike the tall telephone poles. Avoid using any electrical equipment such as hair driers, electric razors, microwave ovens, or washers et cetera. Today, most tall buildings are protected by lightning rods. This concept was first introduced by Benjamin Franklin in 1749. These are metal rods which are placed on top of the highest, most exposed part of the building. A wire leads from the rod and is buried underground away from the building. This attracts the lightning and conducts its discharge away from the building and into the ground. Aerials and power lines are protected by using lightning arrestors. These have a space between the line and ground wire which is filled with gas. The lightning discharge causes the gas to ionize, which in turn offers a low-resistant exit for the electricity. Earthquakes An earthquake is a shaking of the ground caused by the sudden dislocation of material within the earth's outer layer, or crust. When forces pushing on a mass of rock overcome the friction holding the rock in place and blocks of rock slip against each other a earthquake may occur. Some earthquakes are so slight, and some occur in such remote areas, that they are barely felt. Others are so violent that they cause extensive damage. Causes of Earthquakes Earthquakes are caused by stresses below the earth's outer surface. These stresses usually build up until the rocks fracture along a "fault plane." This causes vibrations, also known as seismic waves. Seismic waves will then travel in all directions from the area of fracture. In large earthquakes seismic waves may be detected over the entire earth. Earthquakes can be caused by volcanoes in certain cases. Nuclear explosions under the ground can create waves that are very similar to natural seismic waves. The seismic energy created in a atomic bomb is one hundred-thousandth that of the largest earthquake. Location and Distribution of EarthQuakes Earthquakes take place or have taken place in all parts of the world. Frequent activity occurs along certain belts. 80% of all seismic energy is generated from a belt that is found at the border of the Pacific Ocean. A great deal of volcanoes are also found there, and volcanoes set off many earthquakes. Japan, the Philippine Islands, New Guinea, and New Zealand are all part of the Pacific belt. A second seismic belt produces 15% of seismic activity. It goes through southern Asia to the region of the Mediterranean Sea. The final 5% of seismic energy comes from parts of the Arctic, Atlantic, and Indian Oceans. Antarctica and Australia experience the least amount of earthquake activity then any other areas of the world. Effects of Earthquakes Earthquakes produce various damaging effects to the areas they act upon. This includes damage to buildings and in worst cases the loss of human life. The effects of the rumbling produced by earthquakes usually leads to the destruction of structures such as buildings, bridges, and dams. They can also trigger landslides. An example of how an earthquake can lead to even more destruction is the 1959 earthquake near Hebgen, Montana. It caused a land slide that killed several people and blocked the Madison River. Due to the fact that the Madison River was blocked, a lake was created which later flooded the nearby town of Ennis. Besides producing floods and destroying buildings, earthquakes that take place under the ocean can sometimes cause tsunamis, or tidal waves. Tsunamis are high and long walls of water which travel at a very rapid rate. They are notorious for destroying entire populations and cities near coastlines. In 1896 Sanriku, Japan, with a population of 20,000, suffered such a fate. Droughts Drought is a period or condition of unusually dry weather within a geographic area where rainfall is normally present. During a drought there is a lack of precipitation. Droughts occur in all climatic zones. However, its characteristics vary significantly from one region to another. Drought usually results in a water shortage that seriously interferes with human activity. Water-supply reservoirs empty, wells dry up, and crop damage ensues. Its seriousness depends on the degree of the water shortage, size of area affected, and the duration and warmth of the dry period. In many underdeveloped countries, such as India, people place a great demand on water supply. During a drought period there is a lack of water, and thus many of the poor die. Most precipitation depends on water vapor carried by winds from an ocean or other source of moisture. If these moisture-carrying winds are replaced by winds from a dry region, or if they are modified by downward motion, as in the center of an anticyclone, the weather is abnormally dry and often persistently cloudless. If the drought period is short, it is known as a dry spell. A dry spell is usually more than 14 days without precipitation, whereas a severe drought may last for years. Statistics indicate that every 22 years a major drought occurs in the United States, most seriously affecting the midwestern states. The drought of 1933-35, during which large areas of the Great Plains became known as the Dust Bowl, is an example of a disastrous drought that took place in the United States. The effect of the drought was brought about by overcropping, overpopulation, and lack of relief measures. Although drought cannot be reliably predicted, certain precautions can be taken in drought-risk areas. These include construction of reservoirs to hold emergency water supplies, education to avoid overcropping and overgrazing, and programs to limit settlement in drought-prone areas. The Southern Africa Development Community monitors the crop and food situation in the region and alerts the people during periods of crisis. Effects of Drought Drought produces a large number of impacts that affects the social, enviornmental, and economical standard of living. Its affects spread far beyond the physical effects of drought itself. Water is integral to produce goods and provide certain services.Some direct impacts of drought are reduced crop, rangeland, and forest productivity; reduced water leves; increased fire hazard; increased livestock and wildlife death rates; and damage to wildlife and fish habitat. A reduction in crop productivity usually results in less income for farmers, increased prices for food, unemployment, and migration. The many effects of drought can be listed as economic, environmental, or social. Please click here to see the list of its many negative effects. However, not all impacts of drought are negative. Fortunate agricultural producers located outside the drought area benefit by selling their goods at higher prices. Drought is also associated with increases in insect infestations, plant disease, and wind erosion. Droughts may cause problems with insects and diseases to forests. Forest fires increase dramatically during periods of droughts Farmers are not the only ones who suffer from droughts. Retailers who provide goods and services to farmers must deal with reduced business. This later leads to unemployment and loss of tax revenue for the government. The recreational and tourism industries are seriously damaged because tourists do not want to travel to a country that is suffering from a severe water shortage. Shortages of certain goods results in the costly importation of necessary goods from outside the affected area. Environmental losses are caused by damages to plant and animal species. Wildlife habitat, and air and water quality are usually damaged due to a lack of water and an increase in forest and range fires. Most of the effects of drought are short-term, and as the drought comes to an end many problems are solved. However, many other environmental effects hinder the area for long periods after the drought is over. For example, wildlife habitat may be ruined through the loss of wetlands, lakes, and vegetation. Some species of animals may be wiped out from the area as well. Other drought-related impacts include social impacts. Social impacts include health, public safety, conflicts between water users, and reduced quality of life. During droughts many people migrate to areas outside the drought-affected location. When this happens, the area loses a great deal of its population, and thu...