Mechanism of secondary disaster

The real fear of earthquakes is not only shaking.
In some cases, what is a "secondary disaster" that exceeds the size of an earthquake?

What is a "secondary disaster"?

A "secondary disaster" is a disaster that is caused by the occurrence of an earthquake.
In addition to the tsunami that caused massive damage in the Great East Japan Earthquake and fires that caused significant damage in the Great Hanshin Awaji Earthquake, secondary disasters also include
There are various things.

What is the difference between an earthquake and a secondary disaster?
Isn't the "tsunami" seen in the Great East Japan Earthquake one of the secondary disasters ...?
It's a horrible second disaster!
The second disaster is not only a tsunami, right?
Eh, really? It's super cool!
Tension is too high ...


A fire is a secondary disaster which has a high probability of occurring due to an earthquake .
Even if it's a small shake, there is a good chance that it will develop into a big fire if you fail to deal with the fire.
The causes of fires are not only gas and oil-powered appliances, but also fires from electrical equipment.
← Pictures of houses spreading fire in the Great Hanshin-Awaji Earthquake
In addition, the rising air generated by the fire may cause a fire whirlwind.
In the case of the Kanto earthquake that occurred in 1923 (Taisho 12), this fire whirlwind has been a catastrophe.

○ Be careful when an earthquake occurs

• Switch off the devices in use. ・ Shut off the breaker (distribution board) at the time of evacuation.
• When using the equipment again after an earthquake, make sure that there are no gas leaks and that there is nothing wrong with the wiring equipment.


Regarding the disaster caused by the tsunami, the Tohoku Region Pacific Coast Earthquake that occurred in 2011 in recent years
I think in the memory that a large tsunami struck the town shortly after the earthquake.
In the first place, tsunami is a human disaster such as loss of life, physical damage such as damage to facilities of ships and ports, and housing,
In addition, there are three types of indirect damage such as flooding and flooding of fields.
The size of the damage caused by human disasters is not limited to the size of the tsunami.
It is greatly influenced by the time when the earthquake occurred and the living condition and evacuation situation of the town.
* The picture of the tsunami is not included as a consideration for those who feel stress. Please note.

Ground crack

Strong ground motions can cause cracks on the surface. This is a crack in the ground.
It is usually an irregular crack and easy to form on soft ground or slopes such as landfills.
Mountainous areas may suffer from falling rocks and landslides, and in some cases the topography may change.
← Photograph that ground crack occurred in Niigata Chuetsu-oki earthquake (2007)

Liquefaction phenomenon

Liquefaction occurs when the ground, such as a landfill, is loose and the water in the ground increases, and the ground weakens.
Unlike other lands, landfills are evenly mixed with sediment particles and water particles.
When a large earthquake occurs, heavy soil moves down and water particles move to plum, which weakens the ground.
Cars and buildings will sink and manholes will pop up.
← A picture of liquefaction occurring in Urayasu city and a manhole jumping out

Anything is scary ...
Next, I will introduce two major disasters that I have heard on TV in the future.
What are the two major disasters?
It is an earthquake directly below the capital and Nankai Trough earthquake.

Next episode
EP03 / It does not necessarily happen in Tokyo! ? Tokyo Metropolitan Earthquake