Introduction
The stay of mankind on planet earth has often witnessed moments of helplessness when natural disasters have stuck; thus, destroying many lives and disorienting mankind in the process. From our earliest ancestors to the modern man, we have not been safe from the anger of natural disasters.
Ranging from volcanoes, hurricanes, tornadoes, and the destructive tsunamis, we are susceptible to an array of natural disasters that is always waiting to strike. Such was the case when a tsunami hit the coastline of Sri Lanka on 26th December, 2004.
Without warning, thousands of people were killed by the 2004 tsunami. Such is the common story that is often told when catastrophic disasters like a tsunami strikes. Although we have evolved in science and thus learned many secrets of our world, we have not been able to subdue natural disasters. Since all life is precious, it is our responsibility to use the resources we have, and adopt a behaviour that can help us preserve even a few lives during catastrophic events.
Generally, a tsunami can be defined as a series of wave disturbances which usually originate from a vertical displacement of a water column (Abek 1561). The word “tsunami” has an origin in the Japanese language. Here, “tsunami” can be directly translated as a series of waves that often form at bays (Hassain 51).
Usually, anything with a potential of displacing, or moving a large volume of water can cause a tsunami (Vitarana 84). The most common causes of tsunamis include earthquakes, moving heavenly bodies such as meteorites and asteroids, volcanoes, and landslides (Vitarana 84).
Earthquakes
Most tsunamis originate from earthquakes. Once an earthquake occurs on a sea bed, a large mass of water is displaced upwards. Due to the force of gravity, the displaced volume of water will move downwards to regain its original position (Vitarana 84).
A repetitive cycle where a water column moves up and down is created; hence forming a wave. Usually, a displacement of a water column will occur when part of a sea bed is displaced (UNEP 12). A fault line in the earths crust can especially create a boundary where a vertical displacement of the sea bed can easily occur (Liu 106).
Earthquakes that occur on subduction trenches are the main causes of most tsunamis (Liu 106). The tsunami waves that originate from an earthquake source can then move away from the place where they originate thousands of miles (Moore 143). Knowing the magnitude of an earthquake can especially be useful in determining the scale of tsunamis that have travelled thousands of miles from their source (Hassain 51).
Landslides
Tsunamis can also originate from landslides. Landslides can occur at the seabed, or at the coast (Vitarana 84). Possible causes of such landslides include the earthquakes, the erosion of sea slopes, and volcanoes (Hanson 67).
The erosion of coastal slopes can occur as a result of rain action, from sea waves, and storms (Hanson 67). Due to a displacement of sea water as a result of displaced debris from landslides, a series of waves that has a potential of causing a tsunami is formed (Van 24).
Volcanoes
When a volcano occurs above the surface of the sea, but in proximity to the sea’s surface, a large quantity of rock debris is thrown into the sea. When such debris falls into the sea, it displaces water; hence, creating waves that can cause a tsunami.
However, volcanic eruptions that occur under a sea are more hazardous in forming tsunamis (Hassain 51). Tsunamis can originate from a displacement of water that is caused from a rising slope of a volcano (Van 24).
Besides, gases that are usually released from an erupting volcano can also cause a large water displacement; hence, forming a tsunami in themselves (Hanson 67). Moreover, a volcano can also trigger an earthquake, which can then trigger a tsunami (Damen 106).
Meteorites, Comets and Asteroids
Our earth is constantly in danger of colliding with heavenly bodies like comets, asteroids and meteorites (Hanson 67). While one might think that great damage from such collisions will occur if such bodies hit the earth’s surface in an area that is densely populated (such as a town), a greater catastrophic damage will happen if such bodies strike at sea (Abek 1561).
For example, scientists estimate that if an asteroid that is about six kilometres in size was to fall in the middle of the Atlantic Ocean, a third of the US population would be killed (Damen 106). The gigantic speed and size of a typical asteroid can create huge waves (tsunamis) that can cause a devastating damage to our population (Liu 106).
Although the possibility of us experiencing such a collision (from a heavenly body such as a comet) is almost zero, there is always a possibility, however remote, of such a catastrophe (Abek 1561).
Activities of Man
Any human activity that can result in a displacement of a large volume of sea water can lead to the build-up of a tsunami wave. The carrying out of nuclear tests in deep sea can especially release large amounts of energy which can then displace large volumes of sea water; hence, leading to the development of a tsunami wave.
Characteristics of a Tsunami
As we had seen earlier, a tsunami originates from a displacement of a large volume of water (Van 24). Such a displacement creates a wave that moves up and down. A tsunami is therefore a wave that is very similar to the kind of wave ripples that we usually observe when we throw a stone in a tank of water (Damen 106).
Very often, a tsunami will travel as a series of multiple waves; hence, it is usually called a train of waves (Damen 106). Once it forms, a tsunami can travel thousands of miles in the sea before reaching a coastal area (Liu 106).
For example, a tsunami with an origin in the Atlantic can travel at an incredible speed of over 1000 km/hr to reach the Japanese coastline within 24 hours. Usually, tsunamis travel at very high speeds in deep sea waters (Hassain 51).
However, on reaching shallow waters, the speeds of tsunamis usually reduce gradually (Van 24). Such behaviour results from an energy flux that remains constant during a wave travel (Hanson 67). Since the energy flux of a tsunami is proportional to the speed and amplitude of a tsunami wave, tsunamis at deep waters will travel at high speeds and low amplitudes.
Unlike their counterparts in shallow waters, such tsunamis will usually consist of waves that are small in amplitude and long (in horizontal size) (Abek 1561). Indeed, it is sometimes difficult to physically observe a tsunami wave that is travelling in the deep sea (Moore 115).
However, as a tsunami moves into shallow waters towards a coastal area, its speed decreases while its amplitude increases. Travelling at a speed that is proportional to the square root of gravity constant multiplied by depth, a tsunami that is travelling in water that has a depth of five kilometres can move at a speed of over 800 km/hr.
On hitting a coastline, such a tsunami can travel at amplitude that is within ten to fifty meters. Such tsunamis can be observed as a series of water waves forming a series of rises that alternate with falls at the coastline. Usually, tsunamis can occur for several hours.
Like any other wave, tsunami waves can add to one another to form waves with higher amplitudes, or subtract from one another to form waves of lower (or zero) amplitudes (Moore 116).
The 2004 Tsunami in Sri Lanka
The date of 26th December, 2004, will be remembered for a long time by many people in Sri Lanka. During this particular date, a tsunami of a large magnitude and scale hit the coastline of Sri Lanka (Liu 117). The 2004 tsunami in Sri Lanka was caused by an earthquake of a high magnitude that occurred in the western coast of Sumatra (Moore 138).
The focal depth of this particular earthquake was about thirty kilometres (Liu 117). Described as the worst earthquake to occur in the history of our planet in the past five decades, the earthquake that caused Sri Lanka’s tsunami measured over 9.0 on the Richter scale (Liu 106).
The above earthquake originated from an interaction of Australian, Sunda, and Burmerse tectonic plates. Here, as much as 30 meters of the sea bed covering a distance of over one thousand kilometres was displaced (Abek 1561).
Thus, the displacement that was caused by the described tsunami resulted in a vertical displacement of a very large volume of water; hence, creating a tsunami (Moore 129). Moreover, the 9.0 earthquake caused a series of about fifteen other earthquakes in the affected region.
As a result of a water displacement (caused by the resulting upward movement of the sea floor) that was caused by the 9.0 earthquake, a series of three tsunami waves was formed (Liu 106). Time duration between these tsunami waves averaged about twenty minutes.
Effects of the 2004 Sri Lanka’s Tsunami
When a tsunami reaches a coastline, it travels with high amplitude (from ten meters to even fifty meters). Thus, water overflows from the coastline towards the inland. Such a moving volume of water travels at a high speed, and with enormous energy that can cause huge destructions.
The 2004 tsunami, which hit the Sri Lankan coastline, affected more than two thirds of the Sri Lankan coastline. More than 20% of the Sri Lankan population was thus affected by the 2004 tsunami. Here, the moving tsunami wave drowned and killed thousands of people.
There were especially many deaths since the country was not expecting a tsunami, and was not therefore prepared for an emergency evacuation. It is reported that due to ignorance, thousands of Sri Lanka’s went to learn of what had happened when the first of the three series of tsunami waves hit their coastline (Liu 119).
Usually, due to interactions with a coastline (often leading to a loss of energy), the first wave of a tsunami is often less devastating than those that follow after it. Thousands of people here were thus caught unaware and killed by the second wave of the 2004 tsunami.
The total number of people who were killed in Sri Lanka by the 2004 tsunami has been estimated to be around 31,000 in total (Liu 119). A larger proportion of those killed by the 2004 Tsunami consisted of women and children.
It is estimated that over 10,000 of those killed here during the tsunami disaster consisted of children (Liu 119). Apart from deaths, about seventeen thousand people were injured by the tsunami tragedy while more than five thousand were reported as missing (Liu 119).
Moreover, the overflowing waters of the 2004 tsunami resulted in a massive destruction of property along the Sri Lankan coastline. As a result of the 2004 tsunami tragedy, more than eighty thousand homes were destroyed; hence, displacing about a million individuals as a result.
So as to cater for the needs of the people who were displaced by the 2004 tsunami in Sri Lanka, about 800 camps for the displaced were formed. Many of the people in these resettlement camps had lost their property and livelihoods as a result of the tsunami tragedy. Many others had to undergo psychological trauma due to the negative ways in which the tsunami had affected their ordinary living.
Apart from houses, many infrastructural facilities were destroyed by the 2004 tsunami; thus affecting transport, communication and also posing a reconstruction challenge. A lot of debris could be seen around all the areas that had been affected by the tsunami.
Besides, the 2004 tsunami affected the ground fresh water table through salinization of fresh water sources. It will take a lot of efforts and time to clean some of these water tables that were affected.
Since the Indian Ocean bed has been proven to contain lesser amounts of titanium as compared to the Pacific Ocean, more studies will be required before we can determine if large amounts of titanium was deposited inland during the 2004 tsunami.
Economic Impacts
The 2004 tsunami affected the economy of Sri Lanka in several negative ways. Many people lost their sources of livelihoods as a result of the 2004 tsunami. Some of these people who had lost their livelihoods had lost their businesses and houses, which had been destroyed by the destructive tsunami waves (Dawson 224).
Moreover, since a large community of the Sri Lankan population depends on fishing, many fishermen became poor as a result of losing their boats to the destructive tsunami waves that had hit their coastline (Dawson 224). A United Nations report on the 2004 tsunami catastrophe estimated that about two hundred thousand people in Sri Lanka were in danger of becoming poorer following the 2004 tsunami tragedy (Dawson 224).
Because a large part of hotels, beaches, among other tourist facilities were destroyed by the tsunami tragedy, the tourism economy of Sri Lanka was affected negatively. With no places were tourists could visit and relax, the number of tourists arrivals in Sri Lanka decreased significantly.
As a result, many people who were directly employed by the tourism sector lost their jobs. Moreover, due to a decrease in tourist arrivals, Sri Lanka was thus losing an important source of foreign exchange for developing her economy.
With a destruction of her infrastructure as a result of the tsunami tragedy, billions of dollars were needed for restructuring. With limited resources, it will be difficult to meet the cost of restructuring affected infrastructure. Meanwhile, as a result of infrastructural destruction, many businesses were affected negatively (Dawson 224).
Many of these businesses depend on telecommunication, electrical power, and transport to carry on with their day to day activities. Most of these businesses are small businesses that contributed positively to the Sri Lankan economy (through employment of people and paying of taxes).
Since most of these businesses have suffered from a displacement of people (hence a loss of market and human resource), and also from a physical damage of their properties and facilities, they have found themselves in a very repelling environment to operate in; thus, limiting their capacity and output to the Sri Lankan economy.
Measures that can be taken to Avoid Future Tsunami Disasters
No matter how much we prepare, we can never be ready for natural disasters. However, a possible measure of precautions and preparedness can help us to avoid, or minimize the destructive effects of natural disasters.
Although there is uncertainty on the effectiveness of using technology to mitigate the effects of natural disasters such as tsunamis, we should always work in the direction of utilizing such technologies if we can save a few lives as a result.
Together with several countries, the United States has developed and placed sensors at specific areas on the seabed of the Pacific Ocean. These pressure sensors have been designed to detect possible tsunami waves (UNEP 18).
Since tsunamis consist of waves that have rising and falling amplitudes, the resulting difference in the depth of water can cause pressure alterations at sea beds. These pressure alterations can thus be detected by pressure sensors at the seabed (Meihde 56).
However, since such a process of measurement is highly complex, it is very difficult for sensors at the sea bed to have accuracies that can detect tsunami waves. Still, the progress that has been made in using sensors to analyse data for a possible tsunami waves is positive (UNEP 12).
Moreover, since tsunamis interact with the coastline in a way that is difficult to predict, it is equally difficult to predict their behaviour. Sometimes, tsunami waves can add together or cancel one another; hence, making it difficult to determine their eventual behaviour (Meihde 56).
Several researchers remain uncertain if the tsunami warning technology in the Pacific Ocean can be replanted in the Indian Ocean. Still, Sri Lanka has been part of an ongoing program that has been working with several other countries to develop a system that can monitor for possible tsunamis before they occur (Liu 106).
Under the tsunami warning system, The Sri Lankan meteorological department will work together with Japanese technologies and the Pacific Tsunami Warning System (PTWC) to possibly help in the detection of future tsunamis (Yadav 107).
Although we do not have a reliable system of detecting tsunamis, the above development is progressive in developing reliable systems that can be useful in detecting and monitoring tsunamis before they hit a coastline (Andrew 23). However, since the Indian Ocean bed is different in structure and complexity to the Pacific Ocean bed, there is a need for scientists to develop a warning system that is unique to the Indian Ocean (Patra 362).
Currently, there has been a debate on whether to allow building of houses a few meters from the coastline (UNEP 21). Here, it will be useful to develop buildings that are protective and safe from tsunamis. Importantly, there is also a need to conserve the Sri Lankan coastline (Meihde 56).
A huge part of the coastline should be planted with mangrove forests (Patra 362). A thick cover of mangrove forests is useful in cutting and breaking tsunami waves before they move further inland (Yadav 107). Conservation of the Sri Lankan coastline will thus be useful in at least reducing possible damages that may occur from future tsunamis (Andrew 22).
Importantly, the political leadership in Sri Lanka has become more aware of damages that can result from natural disasters like tsunami attacks.
With such awareness, the political leadership in Sri Lanka can prepare for emergencies and move with speed to mitigate damages that can arise from similar disasters in the future (Patra 362). Here, it will be useful to develop a quick response system that can help in quick evacuations and treatments during times of natural disasters (Yadav 107).
An important area that needs to be utilised for the purposes of mitigating the effects of future natural disasters is the use of technology. Here, technology can especially be used to help in assessing the damage that could have occurred following the occurrence of a natural disaster (Patra 362).
Importantly, technology can be employed to communicate with the people who are in danger of being hit by a natural disaster (Andrew 22). It is fruitful to relay information to a target populace with instructions on where they can move to stay safe, what they can do, and how they can ask for help during such times (Meihde 56).
As we had seen earlier, a large number of people who died during the 2004 tsunami attack died from the second wave (Yadav 107). Having heard of what had happened, many people moved in ignorance to witness the effects of the first wave before the more deadly second wave hit (Yadav 107).
With the right communication, these people could have been told to stay away from the beach; hence, cutting on the number of fatalities that occurred (Patra 362). As it has been proven time and again, an effective system of coordination and communication is essential in saving lives during times of natural disasters (Andrew 23).
Conclusion
Natural disasters will always remain a part of us during our stay on planet earth. So as to minimize the loss of lives during natural disasters, it is useful for man to utilize all resources at his disposal to preserve lives during the occurrence of natural disasters.
Such a direction would involve understanding the science of natural disasters like tsunamis, and thus develop measures that can help in warning, planning and rescue programs when natural disasters strike. The 2004 tsunami has especially provided us with important lessons on the direction that we can adopt to prevent massive deaths during such disasters.
Adopting programs that are helpful in preparing for such disasters can be fruitful in saving many lives.
Such a direction would involve developing an efficient system of communication, designing and implementing a standby resource of manpower and machinery for emergencies, using technological systems to warn for possible oncoming disasters, and importantly, developing a system of peaceful coexistence with our natural environment (such as the planting of mangrove forests along coastlines to help in subduing tsunamis).
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