The Dangers of Tsunami
A tsunami is a series of enormously long waves created by a sudden shift in the ocean floor, which resulted from an earthquake under or above the ocean floor. This force produces waves that move in all directions away from their source, crossing entire ocean basins in the process. Tsunamis propagate water columns from the ocean floor to the surface. In contrast, wind-driven waves travel through the topmost layer of the ocean, Earthquakes on converging tectonic plate boundaries are the most common cause of tsunamis. According to the Global Historical Tsunami Database, earthquakes have caused over 80% of possible tsunamis since 1900. Tsunamis differ from normal undersea currents, which due to the gravitational pull of the Moon and Sun.
Tsunamis, on the other hand, do not follow regular waves because their wavelength is much longer. From the point where the tsunami begins, waves move in all directions. We can determine the tsunami's speed determined by water depth, which means it speeds down as it reaches the shore as the water becomes shallower. The water column behind it, on the other hand, is also in deeper water, which means it is going faster and catching up, causing the wave to increase significantly.
Tsunami Hits Minamisoma. (flickr)
We can gauge the size of the wave by the coastline and the ocean floor's physical features. For decades, people have been preparing their structures. According to experts, preparing for such an event would be nearly impossible. Tsunamis grow in size as they travel down long, gradual slopes. It usually occurs near the shore, where the water depth is less than 100 meters. We referred to it as shoaling. The shoaling effect allows waves in the open ocean with a height of about 1 meter to reach 10s or 100s of meters above sea level.
Tsunamis are typically a series of waves, with the first one not always being the most powerful, which is why a small tsunami on one shoreline may transform into a large wave on another. Peaks can be anywhere from 5 to 90 minutes apart. If a disturbance occurs close to shore, the first wave could hit the beach in a matter of minutes without warning. Areas less than 8 meters above sea level and within a mile of the shoreline are particularly vulnerable. Since a tsunami begins in the sea, its waves and receding waters will cause havoc on land, wreaking havoc on any infrastructure in the run-up zone. The most common cause of death associated with tsunamis is drowning, but they may also cause flooding, contaminated drinking water, and gas line fires.
An aerial view of tsunami damage in Tōhoku. (wikimedia)
The Great Tohoku Earthquake is one particular event that shocked the world on how tsunamis can damage human lives and properties. The Tohoku earthquake struck off the coast of Japan in 2011. The earthquake reached a magnitude of 9 on the Richter scale, making it a devastating earthquake that wreaked havoc on Japan. Two tectonic plates collided at a destructive plate boundary, specifically a subduction zone, causing an earthquake to occur. The Pacific tectonic plate, which is denser, slipped under the North American plate, which thinner.
As the massive plates collided and trapped, the energy built up as they attempted to free themselves. The pressure eventually built up, and the plate finally gave way, resulting in an earthquake. The water was displaced by the sudden uplift, resulting in the birth of a tsunami. The tsunami slammed into Japan's northeastern coast. In the first 30 minutes, a 40-meter-high wave crashed into the shore, followed by nine more 10-meter-high waves.
The city of Rikuzentakata, Iwate Prefecture, suffered extensive damage from the tsunami. (wikimedia)
Tsunami flooding on the Sendai Airport (wikimedia)
According to Japan's National Police Agency, over 15,000 people died as a result of the disaster. Furthermore, there are 2000 people injured, 530 000 people were homeless, 1.2 million homes left without power or water, 50 000 homes were damaged, and 32 bridges destroyed. The earthquake caused a system breakdown at the Fukushima Daiichi Nuclear Power Plant. It resulted in a level 7 nuclear meltdown, which causes to release of radioactive materials was one of the most devastating effects. TEPCO, the Tokyo Electric Power Company, confirmed in July 2013 that the plant leaks about 300 tons of radioactive water into the Pacific Ocean every day. The radioactive material was known as cesium-134 and cesium-137 radioactive isotopes.
NOAA tsunami energy map. (wikimedia)
A seismogram recorded in Massachusetts, United States during the Tohoku Earthquake. (wikimedia)
Scientists have no way of knowing when or where a tsunami will occur. There are tsunami warning centers that alert the public when an earthquake would likely produce a tsunami. It sends out warnings to the coastal residences and the public, in general. The center keeps an eye on networks of deep-ocean and coastal sea-level observation systems, which track tsunamis. They used the data to predict coastal impacts and inform local evacuation decisions using computer algorithms. Scientists work to improve the warning centers and to assist communities in becoming more prepared to respond.
Therefore, a tsunami is one of the most devastating natural disasters that result in the loss of many lives and property. Governments of various countries and states, especially those in coastal areas, must take different measures to reduce the loss that this natural disaster can cause. We must realize that government alone can only take a minimal number of safety measures. We should give a hand by preserving mangroves in our shoreline. We can monitor our fate by not being afraid and following the above instructions. We must also recognize significant steps toward a better future by doing preparations before tsunami-like events, not during the disaster itself.
Note: The cover image is created by the author using canva. The background image of the is from pixabay
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