Positive and Negative Effects of Tsunami

The effects of tsunamis are negative and surprisingly, positive also. Unfortunately, the negative effects of tsunamis seem to outnumber the positive.

In this article, we will take an exciting journey into the world of tsunamis, particularly the negative and positive effects of tsunamis.

Ready? Let’s go!

What is Tsunami?

Positive amd negative effects of tsunami
Tsunami (credit: pexels)

The word “tsunami” is originally a Japanese word that translates into ‘harbor wave’. It originated from the Japanese words ‘tsu’ meaning ‘harbor’ and ‘nami’ meaning ‘wave’. 

It is reported that this word was coined when a group of Japanese fishermen finished fishing and were returning to shore with their catch only to find that their port was swept by a wave they had not seen.

A tsunami is a series of waves in a water body, usually the sea, that is caused by the displacement of a large volume of water below the sea.

Beneath the ocean are large rocky plates called tectonic plates. These plates move relative to each other at different rates. But when there is a sudden movement of the plates beneath the sea, a certain amount of water is displaced by the sudden rising of the tectonic plate and it forms a wave.

A tsunami starts under the level of the sea and is very turbulent there but the wave on the water can be only 5 meters.

In the deep waters, tsunami waves can be so small that a boat sailing in its center may not detect the tsunami differently from a tidal wave.

This is because the massive wave energy is spread between the sea level and thousands of feet to the bottom of the sea. 

But as the tsunami wave approaches the shore, the ocean becomes shallower and the wave energy is suddenly compressed and becomes volatile.

The ocean floor became higher. The displaced water needs to go somewhere.

The only place to go is up, so the waves get taller and taller as they approach the shore, and with the force that water alone possesses, it sweeps everything along its path. 

Causes of Tsunami

Waves in the sea are caused by different reasons. But a tsunami doesn’t have as many options. There are five possible causes of tsunamis. They include earthquakes, submarine landslides, volcanoes, glacier calving, and meteors.

  • Volcano
  • Earthquake
  • Landslide
  • Glacier Calving
  • Meteor

1. Volcano

A tsunami that is caused by a volcanic eruption is known as a volcanogenic tsunami. Normally, to cause a tsunami, a lot of mass needs to be pushed into a body of water to displace it. A volcanogenic tsunami could occur as a result of the falling away. A partial or complete collapse of the volcano.

In August 1883, the mountainous island of Krakatoa, Indonesia was destroyed by a volcano. When the explosion happened, a portion of the island disintegrated and was blasted into the sea. This caused a tsunami with 36,000 fatalities.

When a volcanic eruption happens, the hot magma and the cold ocean water can also cause a steam explosion, hence, a tsunami.

When the nearly submerged Hunga Tonga-Hunga Ha’apai volcano erupted on January 15, 2022, it launched a powerful pressure of ash into the atmosphere, creating a powerful shock wave in the ocean which displaced a huge amount of water. Thus, a tsunami was generated.

A volcanogenic tsunami can also occur as a result of debris being ejected into the water.


The disastrous tsunami that struck the coastal area off northern Sumatra, Indonesia on 26 December 2004 was caused by a massive earthquake of magnitude 9.0. 

After a series of aftershocks occurred, these earthquakes caused tsunamis that affected not only the country of Indonesia but also damaged small islands and the coastal areas in three other continents- Asia, Africa, and the Middle East. 

While it is hard to know the complete death toll from this disaster, it is estimated that 250,000 persons died during the tsunami.

An advantage of an earthquake-induced tsunami is the fact that it strikes with a warning. Since the earthquake precedes the tsunami,  the quake of the earth can be a signal of the need for safety and depending on your distance to the coast can afford you as much as 5 hours.

3. Landslide

A submarine or undersea landslide also causes tsunamis. This happens when slopes under the water become unstable and fall.

A large mass of sand, gravel, and mud then quickly falls to the ocean floor. This pulls or sucks the water down. When it rebounds, it creates a tsunami wave which moves quickly through the sea to the coast.

A subaerial landslide can also cause a tsunami. It happens on land and moves into the sea disturbing the water. A slope above water breaks off and falls into the ocean, it sends a wave strong enough to cause a tsunami.

It can also be caused when sediments that are unstably set on steep slopes loosen. These loosenings can happen as a result of construction activities, tidal waves, earthquakes, or a combination of factors

Coastal Alaska is an object of landslide tsunamis, both submarine and subaerial, particularly in Southeast and South-central Alaska. This area has produced some of the largest tsunami waves ever recorded. 

Something to note about landslide tsunamis is that, unlike earthquake-induced tsunamis, they can strike with no warning.

The earthquake produces shaking and pressure that notifies. However, a submerged mass may fall to the sea floor and the tsunami wave begins to move without warning.

In 1958, some M7.8 earthquake-induced landslides in Lituya Bay produced a megatsunami with a massive run-up of 1,720. Run-up is the elevation above sea level that a tsunami wave reaches.

4. Glacier Calving

This is the breaking of glacier ice. While most tsunamis are caused by earthquakes and the movement of tectonic plates, global warming has also been contributing to the occurrences of tsunamis.

The heating increases the melting of glaciers making them break off and fall into the water. Glacier calving into the ocean is predicted to be one of the largest contributions to sea-level rise in the future.

5. Meteor

A meteorite’s impact can also cause a tsunami. Space-borne objects can disturb the water from above the surface and displace the water from its equilibrium position. However,  no meteors have been recorded to cause any tsunami in the past.

Direct Impacts of Tsunami on the Environment

The direct impacts of tsunamis on the environment include

  • Solid Waste and Disaster Debris
  • Contamination of water
  • Hazardous Materials and Toxic Substances
  • Contamination of the ocean
  • Damage to infrastructure

1. Solid Waste and Disaster Debris

The water leaves imported waste in the environment. Disposing of these wastes in an environmentally appropriate manner becomes a preoccupation.

Contents of landfills and solid waste disposal sites are re-introduced into the environment. The debris from waste treatment sites provides accumulated dirt to the environment and pollutes the environment.

2. Contamination of water

Water pollution is another crucial direct impact of a tsunami on the environment. The salination of water bodies such as rivers, wells, inland lakes, and groundwater aquifers has occurred in many of the affected countries killing freshwater creatures and affecting drinking water.

This also includes the contamination of water systems. Damaged septic tanks, sewage, and toilets release their contents which infiltrate water systems.

3. Hazardous Materials and Toxic Substances

Toxic substances that have inadvertently mixed up with ordinary debris are introduced into the environment. These include asbestos, oil fuel, and other industrial raw materials and chemicals.

4. Contamination of the ocean

Positive and negative effects of tsunami
contamination (credit: nrdc.org)

After every tsunami, new components are introduced into the ocean; the debris that was dragged into the ocean by the receding waters. And ocean pollution also has its effects.

5. Damage to infrastructure

A tsunami causes damage to environmental infrastructure, buildings, and industrial sites. either complete or partial damage is experienced. Many times, whole sections of infrastructure are washed away.

Effects of Tsunami

The effects of tsunamis can be positive or negative and we are going to look at the two.

Negative and Positive Effects of Tsunami

Positive Effects

  • New Economic Opportunities
  • New study Opportunities
  • Infrastructural Development

1. New Economic Opportunities

In tsunami-prone areas, tsunami-resistant infrastructure and buildings are needed. This offers new economic opportunities for architectural and engineering firms.

The need to rebuild infrastructure also contributes economically to firms.

2. New Study Opportunities

Tsunamis have provided insight into nature. Such natural disasters reveal the abilities of nature to man and make us aware of man-made contributions so we can have an impact on their frequency.

3. Infrastructural Development

The development of many cities began after the tsunamis. There is an opportunity for a re-development of the city; a total or virtually total re-development is possible.

Negative Effects

The amount of water and the energy of a tsunami can cause intensive damage both primary and secondary. For example, the collapse of a building is primary but destructive fire outbreaks caused by a tsunami are secondary.

  • Death and Injuries
  • Damage to Properties and Loss of Resources
  • Fire Explosion
  • Disease Outbreak
  • Economic Losses
  • Psychological Problems
  • Damage to Marine ecosystem

1. Death and Injuries

Death is constantly happening in virtually all tsunamis. The falling of buildings causes death and permanent and chronic injuries. Flooding has many effects one of which is death, and electrocution, power lines in water have caused many deaths also. For example, the 2004 Indian Ocean tsunami killed around 230,000 people in 17 countries.

2. Damage to Properties and Loss of Resources

Properties such as ships, buildings, businesses, boats, trees, power lines, telephone lines, cars, and bridges are damaged when a tsunami hits. Tsunamis carry just about everything in their sight either when they are moving inland or receding to the ocean.

3. Fire Explosion

This is a secondary effect of a tsunami. It is called secondary because it is not a direct effect. Simply put, it is the destruction that is caused by another destruction.

Power plants and power lines can cause fire explosions as was the case with the Fukushima power plant in Japan.

4. Disease Outbreak

Carcass outbreaks cause diseases. Carcasses decaying and lying above the ground may even take a while to be found.

Likewise, sewage leakage into water systems causes a quick spread of disease.

After a tsunami,  there have also been records of the spread of disease among even the livestock population.

5. Economic Losses

This includes the loss of harvests, the destruction of fishing spots, and the destruction of businesses. Human resources are also affected as many are displaced, wounded, or die.

The Indian Ocean tsunami itself resulted in an economic loss of US $9.4 billion. Aceh, Indonesia had the worse hit- economic damage of US $ 4.5 billion; its previous year’s GDP equivalent.

6. Psychological Problems

The loss of loved ones affects victims for many years.

It is reported that an experience of a tsunami causes psychological problems that continue for years, especially among children and adolescents.

7. Damage to the Marine ecosystem

The ecosystem becomes affected/changed. It deposits terrestrial sediments in water bodies. Estuaries, coral reefs, and beaches are altered.

The biodiversity of different species is threatened as a result of a tsunami. For instance,  the Japan 2011 tsunami killed over 110,000 Laysan Albatross chicks on the Midway Atoll National Wildlife Refuge.

How to Survive a Tsunami

In the past, people have constructed sea walls, floodgates, and channels to divert the water but against this force of nature, it’s fallible. 

In 2011, a tsunami surpassed the floodwall built around the Fukushima nuclear plant in Japan and accumulated a death toll of over 18,000.

Now, administrative bodies have decided to focus on early detection through monitoring underground water pressure and seismic activities.

They have also begun to target their efforts at establishing global communication networks so that alerts can be distributed alerts.

Positive and negative effects of tsunami- How to survive a tsunami
Tsunami evacuation sign (credit- Dreamstime)

Some tsunamis are triggered by earthquakes. So if there is an earthquake and you are in a tsunami area, protect yourself from the earthquake first. Drop, Cover, and Hold On. 

Drop to your hands and knees. Cover your head and neck with your arms(against falling objects). Hold on to any sturdy material or furniture until the shaking stops. A great example is to crawl under a sturdy table and hold a leg until the shaking stops.

When the shaking stops, immediately move to a safe place as high and as far from the coast as possible. Since you are in a tsunami-prone zone, do not wait for tsunami warnings and evacuation orders. Just go. If a tsunami doesn’t come, at least you’ve practiced your evacuation route.

If you are outside of the tsunami hazard zone, stay where you are. You’re most likely safer where you are but leave immediately if you are told to do so. 

Evacuation routes often are marked by a wave with an arrow in the direction of higher ground.

If you are in the water, then grab onto something that floats, such as a raft or tree trunk, or climb into a roof floating around. If you remain in the water, you will encounter a lot of injurious debris.

If you are in a boat at sea, it is best to remain there where the waves are nicer. You could face the waves and head out further to sea. 

If you are in a harbor, this is where it strikes hardest. Dock, go inland, as highest and furthest from the coast as possible.

It is truly a wise saying that when nature is too powerful to stop, the best route is to get out of its way.


We have dealt with the positive and negative effects of tsunamis as we proposed to do. However, the negative effects outshine the positive effects. Sometimes whole islands become unrecognizable because of tsunami invasions. A wonder yet a terror.


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