-Japan Earthquake-

The Japanese archipelago is located in an area where several continental and oceanic plates meet. This is the cause of frequent earthquakes and the presence of many volcanoes and hot springs across Japan. If earthquakes occur below or close to the ocean, they may trigger tidal waves (tsunami).

Historic earthquakes

Many parts of the country have experienced devastating earthquakes and tidal waves in the past. The Great Kanto Earthquake, the worst in Japanese history, hit the Kanto plain around Tokyo in 1923 and resulted in the deaths of over 100,000 people.

In January 1995 a strong earthquake hit the city of Kobe and surroundings. Known as the Southern Hyogo Earthquake or Great Hanshin Earthquake, it killed 6,000 and injured 415,000 people. 100,000 homes were completely destroyed and 185,000 were severely damaged.

Earthquake measurement

The Japanese "shindo" scale for measuring earthquakes is more commonly used in Japan than the Richter scale to describe earthquakes. Shindo refers to the intensity of an earthquake at a given location, i.e. what people actually feel at a given location, while the Richter scale measures the magnitude of an earthquake, i.e. the energy an earthquake releases at the epicenter.

The shindo scale ranges from shindo one, a slight earthquake felt only by people who are not moving, to shindo seven, a severe earthquake. Shindo two to four are still minor earthquakes that do not cause damage, while objects start to fall at shindo five, and heavier damage occurs at shindo six and seven.

Preparedness

Every household should keep a survival kit with a flashlight, a radio, a first aid kit and enough food and water to last for a few days. Avoid placing heavy objects in places where they could easily fall during an earthquake and cause injury or block exits. Have a fire extinguisher. Familiarize yourself with the designated evacuation area in your neighborhood.

During and after an earthquake

Falling objects, toppling furniture and panic present the greatest dangers during an earthquake. Try to protect yourself under a table or doorway. Do not run outside, and try to remain as calm as possible. If you are in the streets, try to find protection from glass and other objects that may fall from surrounding buildings.

After a strong earthquake, turn off ovens, stoves and the main gas valve. Then listen to the radio or television for news. In coastal areas beware of possible tidal waves (tsunami) while in mountainous areas beware of possible land slides. 

From : http://www.japan-guide.com/e/e2116.html