Issue 9 / January - March 1995
Catastrophes Of The Earth
It seems that almost everyday the media brings us news of a disaster and resultant death toll. These events occur throughout the world in various forms. Some results from manâ€™s interaction with the highly artificial environment he has himself caused. They include railway disasters and those on ships, submarines, or in the air. The other kind of disaster includes the gigantic convulsions in nature; earthquakes, volcanic eruptions, hurricanes, and tornadoes.
As to the former, the main causes of such disasters, where people are capable of significantly of influencing events are carelessness, inaptitude and inertia. We are often able to cope with and even learn from them. Learning lessons from these bitter experiences leads to improvements in safety conditions. Public places are built to be safer and redesigned to minimize the element of human error and to reduce the risk of accident. However, there is little man can do to arrest or mitigate the great eruptions of the earth.
Nowhere to run
The movement of the earth now affects more people than ever before, according to a recent report from the UN (Kerpelman, 1994). The number of people killed, injured or displaced by disasters has increased by 6 percent a year over the 30 years covered by the report. Charles Kerpelman, its author, says floods killed more people than any other type of disaster. In terms of numbers of people killed and injured, Southern Asia and Southern Africa have been the worst. However, â€˜there is no area in the world that is really safe from disastersâ€™.
Almost every part of the world is susceptible to at least one kind of disaster that has the potential for causing a large number of deaths and significant damage. In the past 100 years, 1 million people have died in earth-quakes, another million in hurricanes, typhoons and tropical cyclones, and as many as 9 million in floods-these figures do not include the millions of deaths from diseases and famine directly caused by these catastrophes (Robinson, 1993). We can learn from examining the several types of disasters and their effects.
The Atlantic is prone to storms, although the most lethal known storm occurred in the Bay of Bengal in November 1970, when winds of more than 160 kilometres per hour led to the death of an estimated half a million people. Over 45,000 people have been killed by hurricanes and intense tropical storms, in the region this century. The Pacific is not exempt. Hurricane Flora killed 5000 in 1963 on Haiti (Knapp, 1990).
Hurricanes are made of strong winds spiraling around the area of calm which is a few kms across. The largest hurricanes spread over hundreds of kilometres and last for many days. When Hurricane Frederic rushed into the Caribbean Sea in September it reached a speed of 230 kilometres per hour. Within a few hours, $2 billion of damage had been caused, explaining why hurricanes are called the insurerâ€™s nightmare in America. They caused a total loss of $44.2 billion from 1987 to 1993 (Legget, 1993).
Volcanoes occur when the earthâ€™s surface is breached and magma flows forth as lava exploding into the air as tuff. All volcanic eruptions are driven by rapidly expanding gases within the magma. The two factors that determine the violence of an eruption are the amount of dissolved gases and how easily they can escape (Beazley, 1992). In the past few decades we have seen the worst volcanic disasters since the start of the century with 25,000 people killed as a result of just three eruptions, El Chichn in Mexico (1982), Nevada del Ruiz in Columbia (1985) and Mount Pinatubo in the Philippines (1991).
Another class of disaster includes earthquakes. There are 150,000 noticeable earthquakes every year, and over a million can be measured using sensitive apparatus. Nowhere is totally free of earthquakes although the must serious ones are concentrated at the well known â€˜faultsâ€™. The earthâ€™s crust is not stable, several kinds of cracks and faults lead to earthquakes. In Tokyo 140,000 people-two-thirds of the city- were killed in 1923. More recently, 10,000 people were killed in Mexico City in 1985 and on 30 September 1993, Killari, a village in India, was reduced to rubble within seconds leaving 10,000 people dead. Of course, earthquakes themselves do not usually kill, the deaths are caused by the collapse of buildings, roads and other human artefacts. Considerable destruction is also caused by the aftereffects like fire, flood, landslide and tsunamis-tidal waves. As it is widely known, earthquakes alone are sufficient to destroy the prosperity of any country.
It is obvious that man cannot resist the giant force of the earthâ€™s shock, however, we can hope to reduce the damages by predicting these events and being prepared. Unfortunately, scientists have not reached a reliable way of prediction.
Forecasting or monitoring?
Having suffered many horrifying cataclysms, man has been trying to develop technologies to predict when and where the next disaster emerge. Today, the technical description and analysis of disasters is far more detailed than the past, but we cannot say that man has achieved any reliable forecasting method. Scientists monitor the catastrophes, that is, they record the earthâ€™s activity, they do not predict.
This century has brought scientists a better understanding of some aspects of hurricanes. Many of the major questions remain largely unanswered. We still have relatively little idea, for instance, why some storms turn into hurricanes and others do not; why some hurricanes make landfall and others remain at sea; what causes a hurricane to wobble or even to reverse. Until the arrival of satellites, hurricanes were awkward phenomena to study, impossible to encompass in their entirety. There are still many things to learn, as noted in Science in 1990 that after 30 years of advances in weather satellites, computer forecasting models, and basic research, forecasters have reduced error in predicting the paths of hurricanes by just 14 percent.
Despite the astonishing technology of the late twentieth century, volcanic eruption prediction remains a humbling science, The history of a volcano, both its geology and its eruptions, if known well enough, is often a good guide to its future behaviour, however, monitoring restless magma is one thing, forecasting when it will erupt is another The chairman of the Coordinating Committee for Prediction of Volcanic Eruptions wrote in Nature that â€˜the prediction of eruptions is extremely difficult....the prediction of the date and time of initial outburst is still like a kind of bettingâ€™ (Robinson, 1993). Recently, radar systems have been used to study erupting volcanoes, however, Rick Hobblit, a volcanologist admits that the single most important piece of information you can have is whether an explosive eruption is in progressâ€™ (Pendick, 1993).
The introduction of a special issue of The Bulletin of the Seismological Society of America stated that â€˜earthquakes do not have to occur where and when we want them or forecast them to occur and our understanding of how and why earthquakes occur and recur, even along the best studied active crustal fault in the world, is rudimentary and incompleteâ€™. Brian Brady, a geologist studying quake-like rock bursts in mines, had made a notorious prediction that a giant earthquake would strike Peru in June 1981. The people of Peru, 66,000 of whom had died in an earthquake as recently as 1970, became jittery and restless as June 1981 approached. The result? Nothing happened. Later Brady wrote, defending himself that â€˜our expanding knowledge of the earth derived from the extraordinary sophistication of new instrumentation, has ironically served to magnify our lack of understandingâ€™ (Robinson, 1993).
Not only to destroy
So far, we have attempted to show the damage caused by disasters and the level of our understanding of them. Bearing in mind that everything in the universe exists or happens for a reason, we may ask ourselves what is behind these catastrophes which cause such great loss to destruction. As Charles Darwin said reporting the ruin of Concepcion in Chile, by an earthquake, â€˜it is a bitter thing to see works, which have cost man so much time and labour, overthrown in one minuteâ€™. But unlike Darwin, we believe every event in the universe is planned. Elsewhere, our scholars have explained this more fully. Here it is sufficient to say that like everything in the universe, disastrous activities of the earth, too, have some benefits to earth and its inhabitants.
Storms and hurricanes help disturb the whole depths of the sea so that plankton-tiny creatures on which most fish swimming near the surface feed-get their food as chemicals from the sea bed. They carry heat from the tropics to the poles helping to even out the world temperatures. If this did not happen the tropics would get hotter and hotter. The poles would ice over without the heat from the tropics. Storms and hurricanes simply do the vital job of carrying surplus energy quickly across the earth. Severe storms such as hurricanes help drought-stricken lands recover. When dry air sits over continents like Asia, a great concentration of energy is needed to make big clouds that will bring rain. This is usually provided by hurricanes (Knapp, 1990).
It is widely known that volcanic eruptions have an overall cooling effect on the earth. Volcanoes cool the globe by injecting large quantities of material into the stratosphere, especially droplets of sulphuric acid. Once in the stratosphere, this material absorbs heat from the sun, preventing it from reaching the ground. This influence can last for several years.
Already, the Pinatubo eruption has cooled the earthâ€™s surface by an average of 0.5 Ã‚Â°C. One other benefit of volcanic eruptions is their 20,000 atm- pressure from magma to surface which helps the earth harden and provides protection from earthquakes. The idea that the volcanoes diminish the ozone layer is denied by recent research which argues that â€˜the chlorine emitted during volcanic eruptions is not responsible for the damage to ozone layer. Two researchers in the University of California have shown that although large amounts of hydrogen chloride are released during some volcanic eruptions, the compound is efficiently washed out in the rain that always accompanies such eruptionsâ€™ (Science, vol.260, p.1O82).
We have attempted to show the effect of disasters in terms of loss of life and money and how far we are from understanding the earth and its activities. Even the dazzling technological advances of the twentieth century could not help us overcome the violence of the earth-shaking events, apart from showing us our lack of understanding. Scientists need to carry on experimenting and studying the mysteries of the world so that man can cope with nature. We must always bear in mind that all those horrifying activities of the earth are not purposeless and free from reason but help maintain the earthâ€™s vitality. They perform tasks that cannot be carried out in more gentle conditions.