What’s exactly a Tsunami- As first monster wave hits Japan’s west coast,  know all about this geological phenomenon

What’s exactly a Tsunami? As first monster wave hits Japan’s west coast,  know all about this geological phenomenon

The first wave of the Tsunami hit parts of the west coast along the Sea of Japan. The waves were approximately one meter high, 3.3 feet, with expectations of a larger wave.

This occurrence followed a 7.6 magnitude earthquake that hit north-central Japan earlier in the day. Subsequently, the Japan Meteorological Agency issued a tsunami warning for the western coastal areas of Ishikawa, Niigata, and Toyama prefectures.

What is Tsunami?

Tsunamis are immense waves triggered by underwater earthquakes or volcanic eruptions. As they approach shorelines, their elevation significantly increases due to the shallower waters.

The pace of tsunami waves correlates with the depth of the ocean rather than the distance from where they originate. Over deep waters, these waves can match the speeds of jet planes, gradually decelerating as they near shallow areas.

Although commonly known as tidal waves, oceanographers discourage this term as tsunamis have minimal association with tides.

What causes a Tsunami?

These magnificent waves are primarily triggered by substantial earthquakes beneath the ocean at the boundaries of tectonic plates. The sudden rise or fall of the ocean floor along these boundaries swiftly displaces the water above, generating the rolling waves that evolve into a tsunami.

Approximately 80 percent of tsunamis occur within the “Ring of Fire” in the Pacific Ocean, an area of intense geological activity marked by frequent volcanic eruptions and earthquakes due to tectonic movements.

Underwater landslides, volcanic eruptions, and in the distant past, the impact of large meteorites crashing into oceans, are also potential causes of tsunamis.

Tsunamis surge across the sea at speeds reaching up to 500 miles (805 kilometers) per hour—equivalent to the velocity of a jet airplane. Traveling at such high speeds, they can traverse the entire Pacific Ocean within a day. Furthermore, due to their long wavelengths, they lose minimal energy during their journey.

In the depths of the ocean, tsunami waves can seem relatively insignificant, often measuring only about a foot in height. However, as they near the coastlines and encounter shallower waters, their pace decreases while their energy and height amplify. The upper sections of these waves move faster than their lower parts, leading to a sudden increase in their vertical dimension.

What happens when Tsunami hits the land?

Before a tsunami’s peak reaches the shore, its trough often arrives first, causing a suction effect pulling seawater seaward, and exposing the sea and harbor floors. This withdrawal is a crucial sign of an approaching tsunami, with the peak wave and its vast water volume hitting around five minutes later, essential for saving lives.

Tsunamis typically arrive as wave trains, increasing the destructive impact with successive waves. Caution is advised as hazards might persist beyond the initial wave, awaiting official safety notices. Some tsunamis flood coasts without colossal breaking waves. Early warning systems like the Pacific Tsunami Warning System, headquartered in Hawaii, aid in protecting coastal regions worldwide with seismic and water level sensors.