Japan is located in one of the most earthquake-prone regions on Earth. Earthquakes of different magnitude occur here several times a day. However, when earthquakes in other countries caused houses to collapse, the Japanese adapted their infrastructure to natural disasters in surprising ways.
As the "country of the East", how did they conquer the fury of nature, and why don't other regions learn from their experience?
Wrath of the earth
About 15 million years ago, the Japanese archipelago was part of Eurasia and was the eastern coastline that surrounded the Bohai Sea and the Sea of Japan. At that time, it was a unified freshwater lake.
Crustal subduction (i.e., the collision of rocky plates where one plate "sinks" below another) significantly raises sea levels in this area.
Geological changes led to the formation of the strait and separated a portion of the land from the mainland, forming the Japanese archipelago. Presumably, some of the last terrestrial connections to the continent disappeared 150,000 to 10,000 years ago. Of course, these events are accompanied by devastating earthquakes and natural disasters.
The process of movement of the crustal plates continues. Here 5 tectonic plates collide with each other: the Philippine Sea plate sinks under the Amur and Okinawa Sea plates, and the Pacific plate sinks under the Bohai Sea plate.
Japan is not alone. On our planet, the oceanic crust expands over a vast area, forming a huge volcanic ring around the Pacific Ocean. It circumnavigates the west coast of the Americas and extends to the east coast of Asia all the way to Australia.
However, the Japanese are not so lucky. The area in which they are located is one of the most active seismic zones. The area is shaking almost all the time. Japan has been experiencing large-scale natural disasters since as long as I can remember. They have to adapt.
What allowed the Japanese to avoid destruction?
Special seismic building standards. When building the skyscraper, the Japanese government and engineers were well aware that the earthquake could not have occurred on a certain day, but could be today. If their projects could not withstand the earthquake, the financial and moral losses would be enormous.
There are two effective techniques to improve seismic resistance: installing a damper and creating a shock-absorbing layer between the foundation and the soil.
Of course, the use of high-quality materials, the characteristics of structural elements (for example, the use of nitinol or steel in load-bearing structures, instead of concrete), and the overall shape of the building are default considerations here.
Inertia dampers are multi-ton pendulums embedded in building structures. They are installed on top of the floor. When buildings are shaken by underground shocks or strong winds, they reduce the magnitude of the building's swing. When the skyscraper tilts to one side, the pendulum swings to the other side, thereby suppressing vibrations according to harmonic vibration theory.
A vibration damping layer is a special suspension system for a building. Depending on the budget and the level of seismic activity in the area, several types of isolation techniques exist.
The foundation isolation pads are equipped with bearings that lay heavy lead plates on the foundation of the skyscraper. The lead plate itself is surrounded alternately by layers of rubber and steel. It is fixed to the foundation by bearings.
The shock absorbers of the "maximum" class are powerful compressor systems located under the foundation. Special sensors automatically detect vibrations in the ground and activate the "protection system". The compressor quickly inflates, allowing the skyscraper to rise 3 centimeters above the ground. The building seems to be suspended above the ground. Even in the strongest earthquakes, the swing is reduced to zero.
Why are these systems only widely used in Japan?
Earthquake-resistant buildings - very expensive to build. They require significant investment. In addition, in the country, the value of human life should be higher than the cost of any building. All this developed over time, when society gradually became richer and there was no political and economic crisis.
In Japan, these technologies did not appear immediately: just 70 years ago, the entire country lived in wooden houses. After the earthquake, these houses were easily rebuilt. However, with the development of the city and the affluence of the Japanese, wooden houses gradually became leisure residences.
In addition, since Japan is located in one of the most dangerous regions on the planet, they must "protect" themselves as best they can. For a country like Armenia or Turkmenistan, such an initiative makes no sense. Although there have been terrible earthquakes in these areas, they only occur 1-2 times every 100 years.
It would be nice for buildings to be built "just in case", but in reality this is not done. No one wants to bear such a cost. In earthquake-hazardous areas, as Turkey's tragic history shows, people save as much as possible on construction. Therefore, Japanese technology is still out of reach.