The last decade has experienced a tremendous increase in numbers of disasters. In 2004, and on boxing-day, an earthquake in Indian Ocean caused tsunami that ravaged the coasts of Asia and Africa continents leaving behind over 230,000 people dead and properties worth 150Billion dollars damaged in fourteen countries. This incidence has been rated as the worst disaster in human civilization. 5 years later, another earthquake struck right in the heart of Haiti killing over 300,000 people within a wink. T?hoku, a Japanese nuclear power plant city in March, 2011 took her turn of the endless onslaught. A devastating tsunami hit the city and claimed over 25,000 lives.
Lagos State, the commercial hub city was not spared from the plain and sharp assaults. The flood of 2011 as a result of a heavy down pour in conjunction with some unregistered astronomical events raised the water level abnormally and blocked the channels designed to drain water away from the roads and discharge to the ocean. Nature went on rampage. Worse enough, the down pour took place at a time when the water surface of the Ocean was experiencing its natural periodic high tides.
Tide is the vertical motion of the surface of the ocean. This up and down motion grows to highest height twice in a day or complete cycle in every 12 hours in the Nigerian waters. A height of 2.7meters, almost the ceiling of a standard house has been recorded in the Niger Delta creeks. Tide results when Newton’s force of attraction acts between the moon and the surface of the ocean, so that the moon literarily pulls up the ocean surface towards itself. This is different from ocean waves. Some rivers especially the ones that empty directly to the ocean reverse their direction of flow at this period. This actually creates a kind of two layers of a the same river flowing in opposite directions, which are, the usual flow beneath towards normal direction and the tide that flows on top in opposite direction. The locales have tried to demystify this double layered to and fro types of rivers and after a long term, synchronized the usage to their advantages. Any member of JTF sent to the creeks and does not know about this science, will surely miss his ways. He could drive his boat conveniently at 08.00 o’clock, only to meet an empty river by 12.00 noon and gets grounded or perhaps gets his boat mysteriously covered by meters of waters. Whenever the famous River Niger assumes these characteristics, one would expect some unbearable flood, at least 200meters either side of the banks that are below 2meter level. Onitsha South end could be flooded, but not the North end. Asaba North end could be flooded but not the South end. The same with any other town by the river side, Lokoja etc.
Disaster can be classified as natural, man-made or both. While man-made disasters such as wars, food crises, and traffic accidents are avoidable, natural disasters such as earthquakes, tsunami, hurricanes, flood or famine cannot be avoided, we simply live with them. The only thing that can happen in this latter case is to manage the situations so that damage to both human and properties are minimized. To an extent, they are predictable using some probabilistic measures unlike the man-made disaster that can hardly be predicted.
Tsunami is the deadliest of all the natural phenomena owing to the speed of the wave. This wave actually goes beneath the surface of the water, hence fishermen hardly notice it until it emerges ashore after surging ferociously inland demolishing anything on its path. This type of wave emerges whenever the water attempts to fill up the sudden gap created by differential settlement of the earth crust as a result of earthquake. The millions of cubic water being forced to fill it up with the unimaginable speed, spills over the gully and off it goes. The simple description of tsunami is ‘retreat and surge wave’ at shore. The word ‘retreat’ is not commonly used by scientists; because, some researchers illustrate it with ‘ram fight’ instead of a spill over. The retreat is when the water from the shore-side makes its own contribution to refill, so that whenever the shore appears to be suddenly and abnormally retreating, expect tsunami.
One cannot exactly avoid natural disasters, one can only manage it. The well-defined disaster management circle consists of preparedness, response, recovery and mitigation (PRRM) pronounced prem. This management chart is applicable to both natural and man-made disasters beginning with preparedness and in that order. The response stage is to alleviate suffering of the affected. In this case, the agencies such as Police, Red Cross, Road Safety, Military, NEMA, and others are given unlimited priorities to traffic and operations. A temporary relief camps are created in schools, churches and other available spaces with food, water and blankets provided. Emphases are placed on survivals. It is after the livings have been rescued that the recovery of the dead and properties is commenced. Mitigation involves relocation of the displaced.
Presently, Nigeria owns three Satellites NigeriaSat-1, NigeriaSat-2 and NigeriaSat-X. These satellites function in conjunction with other satellites being maintained by some collaborating countries to make up the Disaster Monitoring Constellation or DMC. The collaboration makes it possible for adequate coverage of the globe whereby a satellite from this constellation visits Nigerian space at every 4 hours especially because Nigeria lies at the equatorial region where the orbits of the satellites are aligned. These satellites give remote sensing data about land cover and vegetation; hydrology; fire and burn scar mapping; flood monitoring, soil and fertility types; disease control; etc.
In Nigeria, one hardly talks about getting prepared for disasters. This is because; Nigeria is one of the countries that have not been hit by serious natural disasters. It is also probable that she does not expect any major one around the corner. Therefore, how to manage it when it occurs is never in any agenda. However, one cannot rule out a tsunami in Nigeria, and at any moment from now. Mr. Chris King of Keele University in his paper during the Nigerian Geological Survey Agency (NGSA) annual lectures in Abuja 2011 indicated that there exists a hand full of evidence that Nigeria may be in danger of disastrous occurrences of earthquake and tsunami. The main source of fear therefore; is that Nigeria lies on the coast of Atlantic Ocean. As a matter of facts, Nigeria has received a lot of symptoms about this impending danger. The typical examples are the 2011 flood of Lagos and the flood on the banks of River Niger. Going by the memory lane, Nigeria has had a bit of warnings. While one cannot stop the earth and moon getting closer during their astro-potential orbiting, one must learn how to live by the realities they unleash on lives. On 17th of August, 2012, there was an earthquake of 5.2m Richter scale in the mid-Atlantic fault right on same latitude at Nigerian coast. This was big enough to make small surges that can reach Lagos and Niger Delta coastal regions. This occurrence may have swelled the offshore underwater ridges near Lagos which eventually caused the surge into the coast and can be connected to the surge that killed 5 people recently. It is also possible that the swell may have gradually moved inland and responsible for the on-going flood in the Niger Delta region. In 1984 and 2009 earth tremor shook the Shagamu, Ijebu-ode, Aboekuta axis leaving some houses damaged and the evidently projecting bridges over the paved Shagamu-Ore express road. Earth tremor is a minor earthquake. As the saying goes, “a problem identified, is a problem half solved”.
Earthquake itself doesn’t kill; it is the debris from buildings and the speedy water waves (tsunami) that kill. Also, as we get acquaint ourselves with these signs, it is very important that the NEMA gets prepared for the emergency situations. The emergency management circle is usually applied in this situation. Some GIS tools have the emergency management circle that enables us to use computer to manage disasters whenever it occurs.