Earthquake2

In the preceding case of earthquake risk, I mention mainly the feature of the Japanese earthquakes from the macro points of view. It’s needless to say that earthquakes happen not only in Japan but also in any other countries. The Japanese situation for earthquakes, however, is a little different for its geological reasons. Japan is located on some seismic plates which are the fundamental causes to shake the land. As a result, the small island is much exposed to the earthquake risks. Furthermore, on the surface of the land there are a lot of active faults caused by successive land jolts since ancient times. This feature complicate its risks. Next we have to think how earthquakes give damages to our life.

In the past one hundred years, there have been at least several gigantic earthquakes(over magnitude 7 on the Richter scale). Of course each earthquake brought about huge damages not only to the buildings but also human lives. Among them there was a earthquake recorded in the Japanese history. It’s the Great Kanto Earthquake, which occurred on September 1^st in 1923 almost just at noon, involving over 140,000 deaths. To take a look at the cause, many of them died from fire. This was due to the fact that the earthquake happened during lunchtime(people used fire for cooking), and that most houses at that time were built wood, which easily spread fire.

On the other hand, in the Great Hanshin earthquake which had taken the lives of over 6000 people early in the morning in 1995, most victims were caused by the pressure of collapsing buildings. The deaths by fire seemingly accounted for only 10% of the total. Why did ironically God give sneak attacks to Japan? Both of the earthquakes were unguarded. In the last one, what could we have done for the big jolt during we were asleep. When it comes to countermeasures on the spot, tremendously important is the first reaction in the very short moment of about 10 seconds just after starting shaking. It’s no exaggeration that your life depends on it, hiding under the safe places or escaping from structures although you couldn’t move at all.

Most of the collapsed houses or even commercial buildings were so old that they didn’t meet the construction standard law which was revised in 1981. This revision was to upgrade the standard for quake-resistance structure to endure the big jolt equivalent to the historical great earthquake in 1923. Nationwide, however, almost half of al houses and buildings standing on the land of Japan didn’t meet the standard when the Hanshin great earthquake happened. It’s because the law went into effect for newly-constructed buildings afterward.

On reflection, the government legislated a new law in order to promote anti-earthquake retrofit in 1995 shortly after the Great Hanshin Earthquake. The act imposes the owners and occupants of houses to make possible efforts for retrofit. If they want to remodel the houses for earthquake resistant ones, they are given subsidies and favorable treatments in taxes or loans. Despite of those official efforts, there is no outstanding anti-quake movement yet partly because of a lack of Japanese risk senses toward earthquakes.

Even though you are living in a very strong apartment which can resist any size of earthquakes, you may face another risk caused by shakings different form fire or collapsing. It's liquefaction. This is a phenomenon that buildings sink below the ground, usually seen in reclaimed land near port cities or around the mouth of rivers. Japan is so small with a big population that it's been reclaiming land from sea. Geologically saying, soils become fluid by big earthquakes because grains of soil once firmly combined will come apart. The soil will lose its strength. That's why even heavy structures such as reinforced apartments sink into the ground like materials do into water. If a big earthquake occurred, it would be rather riskier for the residents on the first floor to be saturated into the basement. You couldn't feel OK to see no apartment's collapse after big earthquakes.

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