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Why is Japan prone to tsunamis?

Description: Tsunamis, are natural disasters that can unleash devastating consequences upon coastal communities. This article delves into the definition of tsunamis, the processes that lead to their formation, their impact on coastal areas, regions most prone to tsunami occurrences, and the geographical features associated with these catastrophic events.

Tsunami is a Japanese word with the English translation, "harbor wave." It is a very long-wavelength wave of water that is generated by sudden displacement of the seafloor or disruption of any body of standing water. 

An underwater earthquake is the most common cause for a tsunami, but all underwater earthquakes do not cause a tsunami. The earthquake needs to be a large enough earthquake of around 7.0 magnitude or bigger.

Underwater earthquakes happen because oceanic and continental plates, which are huge areas of the earth’s crust, push into each other and build up pressure. The pressure builds and builds until eventually the oceanic plate slips under the continental plate releasing all that pressure and energy in the form of an earthquake. If an underwater earthquake is large enough, the ocean floor will make significant movements, therefore the water above the sea floor will also move. The ocean water is pushed upward causing a large ripple that begins to travel through the ocean.

The difference between tsunamis and normal waves or waves caused by strong wind is the extreme distances between wavelengths. This is the distance from one wave crest to the next wave crest, which can be between 100 and 300 km. A further feature of tsunamis is their relatively small wave height on the open sea - mostly between half a metre and one meter. Even though they can travel up to 1 000 km/h, these waves are generally not noticeable in deep waters. The wave itself only becomes dangerous once it reaches land.  A trough of a tsunami wave approaches the land first; because of this the water is pulled back into the sea by enormous currents.

Impact of Tsunamis

Tsunamis can have devastating consequences on coastal communities. Upon reaching shorelines, they can inundate low-lying areas, causing widespread flooding and destruction. The force of these waves is capable of eroding coastlines, submerging buildings, and displacing entire populations. The sheer volume and energy of a tsunami make it a formidable force that can leave lasting impacts on both human and natural environments.

Regions Prone to Tsunamis

Certain regions of the world are more susceptible to tsunamis due to their proximity to tectonic plate boundaries. The Pacific Ring of Fire, which encircles the Pacific Ocean, is a hotspot for seismic activity and is consequently more prone to both earthquakes and tsunamis. Countries bordering the Pacific, such as Japan, Indonesia, and Chile, often experience these natural disasters. The Indian Ocean is also susceptible, as seen in the devastating 2004 Indian Ocean tsunami that affected multiple countries, including Indonesia, Thailand, Sri Lanka, and India.

Why is Japan prone to earthquakes and tsunamis?

Japan is situated along the ‘Pacific Ring of Fire’, which is the most active earthquake tectonic belt in the world. The ‘ring’ refers to “an imaginary horseshoe-shaped zone that follows the rim of the Pacific Ocean, where many of the world’s earthquakes and volcanic eruptions occur,” according to a report by Live Science.

Within the Ring of Fire, there are different tectonic belts, including the Pacific Plate, Eurasian Plate, and Indo-Australian Plate, which keep meshing and colliding with each other, causing earthquakes, volcanic eruptions and tsunamis.

In 2011, Japan was hit by a 9.0 magnitude earthquake and a resulting tsunami which devastated its northeastern coastal communities, killing around 18,000 people and displacing tens of thousands. Those tsunami waves led to a nuclear meltdown at the Fukushima power plant, causing the most severe nuclear accident since the 1986 Chernobyl disaster in the Soviet Union.

Preparedness and Mitigation

Efforts to mitigate the impact of tsunamis involve early warning systems, community education, and land-use planning. Governments in tsunami-prone regions invest in technology that monitors underwater seismic activity, allowing for prompt warnings when significant disturbances are detected. Community preparedness programs educate residents on evacuation procedures and the importance of moving to higher ground in the event of a tsunami warning.