Understanding Characteristics Tsunami Waves and Classifications

Countries in the Pacific Ring of Fire are prone to tsunamis. Therefore, they must have an excellent understanding of this disaster by learning more about characteristics tsunami waves. This understanding can help them develop the most effective disaster management strategies. 

Tsunamis are extremely hazardous and damaging. It has caused widespread destruction and loss of life in the past. Consequently, countries with high tsunami risks must understand tsunamis and use this knowledge to formulate disaster risk reduction strategies, such as utilizing tsunami wireless alerts.

Tsunami: What is it?

Tsunamis are a natural hazard that typically occurs after an earthquake. This natural disaster comes in a series of waves. Moreover, those waves have an extremely long wavelength. They travel across an ocean and cause destruction when they hit low-lying coastal areas.

Earthquakes are not the only phenomena triggering tsunamis. Landslides and volcanic eruptions may also produce those devastating waves. In general, tsunamis occur when there is a displacement of seawater due to an underwater disturbance.

Characteristic Tsunamis

Each natural disaster in this world has distinctive characteristics to differentiate it from other natural hazards. What are tsunami characteristics?

1. Wave Speed

Tsunami can move extremely fast. Its maximum speed is as fast as the speed of a jet airplane or about 800 kilometers per hour. With this speed, those deathly waves can cross an ocean in less than 24 hours.

However, the speed of tsunami waves will decrease when they hit the shorelines. The speed of those waves typically ranges between 30 to 50 kilometers per hour when sweeping the coasts.

2. Wave Height and Energy

In the deep ocean, tsunami waves look like tidal waves because their height is only a meter above the seawater surface. Consequently, sailors sailing ships in the sea rarely recognize those deathly waves as tsunami waves.

However, the tsunami height will increase when the wave hits coastal areas. Reports said those waves can reach 30 m tall above the sea surface. When sweeping those areas, tsunami inundation can extend to 3 km inland.

How strong is a tsunami? A tsunami has a powerful energy. The energy of tsunamis does not increase or decrease when the wave hits the shorelines. It remains constant from its propagation until hitting an island.

3. Long Wavelength and Period

Long wavelengths are other characteristics tsunami waves. The length of those waves expands up to 500 kilometers. Those wavelengths are much longer than that of common tidal waves which are only 100 to 200 meters.

Due to this wavelength, the period or interval between tsunami waves is lengthy. A series of tsunami waves may hit the coast at 10 to 120-minute intervals. This period is much longer than the period of tidal waves which is about 5 to 20 seconds.

4. Drawback Effect 

Several minutes before the first tsunami wave sweeps the shorelines, the seawater seems to ebb away from the shores. Some people often misunderstand this occurrence as a common tidal wave phenomenon. 

Therefore, they play on the exposed ocean floor. As a result, the first tsunami wave can hit them easily if they don’t notice tsunami alert disseminated by authorities.

5. Shoaling Effect

As mentioned before, decreasing speed is one of the characteristics of tsunami waves.  While the waves are slowing down, the wavelength of those deathly waves shortens. Consequently, these waves increase in height and become more destructive. 

Tsunami Classifications

Experts classify tsunamis based on the tsunami location compared to the site of the disaster. What are those classifications?

1. Remote or Transoceanic Tsunamis

Transoceanic tsunamis travel thousands of kilometers away, crossing an ocean. Those deathly waves sustain their energy from their propagation until they hit an island. 

However, transoceanic tsunamis typically need hours to arrive at distant islands. Therefore, people in those affected islands have more time to evacuate. 

Remote tsunamis have occurred several times in the last few centuries. One of them is the 2004 Sumatra tsunami. It traveled thousands of kilometers and destroyed faraway countries, such as Sri Lanka, Thailand, and India. 

2. Local Tsunamis

Local tsunamis affected islands close to their origin. These waves can reach those islands in 10 to 60 minutes. Consequently, people in the coastal areas of these islands get tsunami alerts only a few minutes before the first wave hits their locations.

Long wavelengths, drawback effect, and shoaling effect are some characteristics tsunami waves. From those characteristics, we know that this hazard can be extremely destructive. Therefore, tsunami-prone countries must have the best tsunami EWSs to minimize disaster impact. They can improve their EWSs by integrating cell broadcasters from smsbroadcaster.com.