The Nankai Trough Earthquake

更新日：2024年10月28日

The Nankai Trough Earthquake is expected to be one of the biggest earthquakes to strike Japan. Tokushima City is predicted to be damaged heavily when it strikes. Be prepared for such an earthquake, stay informed about such disasters, and learn how to evacuate when there is danger of a tsunami. Please identify your emergency evacuation sites and high ground evacuation sites designated by Tokushima City, and make sure you know how to get to them. (Refer to the "ダウンロードのリンク　新規ウインドウで開きます。List of Designated Emergency Evacuation Sites（PDF形式：1,279KB）".)

About Earthquakes

How an Earthquake happens

Most earthquakes happen as the result of movements within the earth’s crust.
How an inter-plate (trench type) earthquake occurs:

1

2

3

  1. The oceanic plate in a trench descends slowly under the continental plate by a few centimeters per year.
  2. This movement pulls the edge of the continental plate down. The elastic strain energy around the plate boundary increases over time.
  3. When the stress reaches its limit, the continental plate springs up, causing an earthquake. This movement may also cause a tsunami.

Damage caused by earthquakes

There may be large-scale damage such as buildings collapsing or cracks in the road. Earthquakes also often cause fire, tsunami and other damage.
When a big earthquake strikes, essential services, such as electricity, water, gas, communication services, and transportation, may not be accessible. After a disaster, it is possible that you may have to live in this condition for an extended period of time.

Earthquake measuring (on the Japanese scale) & estimated damage

Earthquake measuring & estimated damage
Seismic intensity Supposed damage and situations
Level 5 low Unstable items fall down, and windows may break.
Level 5 high

TV sets may fall down.
Concrete walls that are not reinforced fall over. Tombstones fall apart.
Level 6 low

In some buildings, walls, tiles, and windows come down.
Some wooden buildings with a low level of earthquake-proof construction may collapse.
The ground cracks and mountains landslide.
Level 6 high

In many buildings, walls, tiles, and windows come down.
Some concrete buildings with a low level of earthquake-proof construction may be destroyed.
The ground cracks and mountains landslide.
Level 7

Even buildings with earthquake-resistance are in danger of destruction.
Large cracks, gaps in the ground, and landslides may cause topographical changes.

Nankai Trough Earthquake Extra Information

Nankai Trough Earthquake Extra Information is a bulletin issued by the Japan Meteorological Agency in situations such as when an abnormal phenomenon is detected along the Nankai Trough or when it is assessed that the possibility of a subsequent earthquake occurring is relatively higher than usual, and so on. The title of the bulletin will be “Nankai Trough Earthquake Extra Information” + a keyword in parentheses (e.g. “Nankai Trough Earthquake Extra Information (under investigation).” Appropriate disaster prevention response will be announced according to the keyword. Please take appropriate actions following the content of the announcement.

Nankai Trough

総務課

〒770-8571　徳島県徳島市幸町2丁目5番地（本館6階）
電話：088-621-5021
ファクス：088-654-2116