Basically, Tsunamis are disasters from nature. These are generated by the ocean waves and their magnitude does not remain the same it varies. There are many factors that can trigger a tsunami, but the most important factor is earthquakes, and it is proven scientifically that large earthquakes cause tsunamis.
Before we go to the main topic let me tell you that what is an earthquake?
This can be defined as the movement of the earth’s crust. Simply the shaking of the ground is an earthquake, it caused by nature i-e volcanic activity, landslides, or by human activities i-e coalmine blasts, and atomic experiments
When the shaking of ground occurs due to an earthquake beneath the sea then suddenly the sea slabs move past each other it causes the overlying water to move fast and creating waves
These resulting waves move away from the earthquake and become tsunamis.
How earthquakes cause tsunamis? – Effect of Minor and large earthquake
An earthquake may be minor or large depending upon its magnitude and this magnitude is very important in triggering tsunamis.
Minor earthquakes that are in a range of magnitude below 6.5 are implausible to generate a tsunami but there are following magnitudes that can cause fewer to higher tsunamis.
An earthquake with a magnitude above 6.5 and below 7.5
An earthquake of this magnitude is likely to generate a tsunami. It is generated due to small changes in sea level. This tsunami never did any much destruction but has the capability to cause damage and causalities. Most of the time it is generated due to human activities.
An earthquake with a magnitude above 7.6 and below 7.8
The earthquakes of this magnitude can trigger large tsunamis that can produce destruction. Especially near the epicenter (the is the point on the earth’s surface that is vertically above the focus of an earthquake).
When this type of tsunami is generated it can be sensed from the distance’s places with small sea-level changes and minor waves but tsunamis that can produce damage to distances places are very rare in this type.
An earthquake that has a greater magnitude than 7.9
Earthquakes of this magnitude can trigger destructive tsunamis that can instigate immense damage. Significant or visible sea level changes might be seen in the distance’s places from the epicenter.
Hence. earthquake is a major factor causing tsunamis.
Read More about how dangerous are tsunamis
Here are some of the tsunamis from the past that have been caused by earthquakes:
Sumatra, Indonesia – 26 December 2004
This tsunami was caused by an earthquake that had a magnitude of 9.1 off the coastline of Sumatra. This earthquake occurred at an intensity of 30 km. the tsunami was 50km tall that reached 5 km inward in the vicinity of Meubolah, Sumatra .
This was the most broadly recorded tsunami with nearly one thousand merged tide gauge and witnesses the measurements from around the world, following places from the US, the UK, and Antarctica did report the height.
North Pacific Coast, Japan – 11 March 2011
This tsunami was generated from an earthquake that had a magnitude of 9.0 that reached depths of 24.4km- making it the fourth-largest earthquake ever recorded.
This tsunami traveled 800km per hour with 10m tall waves flew over the east coastline of Japan, which had killed more than 18,000 people.
Lisbon, Portugal – 1 November 1755
This tsunami was generated by an earthquake that had a magnitude of 8.5. it affected three huge waves that strike on several cities near the west coastline of southern Spain and Portugal.
In some places it was recorded at 30 m high, its waves did see from faraway places as Carlisle Bay, Barbados. The earthquake-generated tsunami had killed 60.000 people in Portugal, Morocco, and in Spain.