What Are Natural Disasters
A natural disaster is an outcome of natural hazards, when they have an
effect on the environment that leads to human, financial, and environmental losses. The serious natural hazards are earthquake, tsunamis, floods, cyclones (Click on the image to see Cyclone Tracy, which occurred in 1974), droughts, tornadoes, and heat waves. The magnitude of the losses depends on the scale of the hazard, and the awareness of the emergency management. The loss may be reduced if the people and the state are physically prepared to meet the consequences of the hazards. The terms disaster, hazards, and vulnerability are interlinked, and have an influence on each other. Thus, a natural disaster will not occur in a deserted area, since humans are not affected. The presence of humans will influence the environment and create the factor of vulnerability. A hazard is the threat potential of an incident that may cause a distress on the humans, and the environment.
Description Of Tsunami
A tsunami consists of an
ocean wave series, created by undersea earthquakes, underwater detonations of nuclear devices, landslides below the oceans, or volcanic eruptions. Tsunamis are also known as tidal waves or seismic sea waves. When the ocean bottom at the plate boundary rises or drops abruptly, it relocates the surrounding water, and waves are launched that become a tsunami. As the tsunamis reach the shores, its destructive potential is increased significantly, though some tsunamis arrive at the shores quietly. The wavelengths of tsunamis may be several hundred miles, with speed up to 600 miles per hour, and height of water exceeding 100 feet. The height of wave lengths will be more along sloping shores and ridges. A tsunami might take place at any condition of the tide, and the coastal areas may be flooded even at low tide. The majority of tsunamis happen in the geographical regions where the occurrence of earthquakes and tectonic shifts are common. It is believed that the earth crust consists of rigid plates that shift over a less rigid inner surface, and these movements cause earthquakes and shifts in earth land masses.
The event of tsunami 2004 is shown in the image.
Tsunami Warnings And Prevention
A tsunami can neither be accurately predicted, nor prevented. However, the geologists and seismologists may initiate a tsunami warning after analyzing the characteristics of each earthquake. Several warning indicators have been developed that can indicate an imminent tsunami, and reduce the devastating effects of a tsunami. Base pressure sensors are attached to buoys that observe the pressure of the water column above, and with suitable calculations estimate the occurrence of a tsunami. Other factors that are used for an assessment of the approaching tsunami are the ocean floor shape, and the general topography. Regions may be active seismically, but all earthquakes may not generate tsunami. Computers are utilized as a tool to analyze the tsunami risk of the earthquakes that occur in vulnerable areas. Countries located around the Pacific Ocean frequently conduct evacuation rehearsals to prepare the people for a tsunami.