Sixteen new locations listed as major active fault zones in Japan

The total number of major active faults in the country has now increased to 113, as the Headquarters for Earthquake Research Promotion of the Japanese government added 16 more faults to the list of active fault zones that could trigger a magnitude-7 or larger earthquake.

More than 2,000 active faults exist in Japan, able to cause an earthquake with a return period of 1,000 to ten thousands of years. However, the term "major active fault zone" is only assigned to the ones being more than 20 kilometers long and having experienced a slip of more than 10 centimeters during a 1,000-year period. Such faults are able of causing quakes larger than magnitude 7, like the 1995 Kobe Earthquake.

For the first time since 2005, the Headquarters reviewed the length, activity and other factors of active faults in three regions of the country and discovered that 16 of them met the conditions for major active fault zones: two faults in the Kanto region, eight in the Chugoku region, and six in the Kyushu region. Two of the faults - the Shinji (Kashima) fault and the Koshiki fault - lay near nuclear power plants. According to The Japan News, both electric power firms state they had already taken the faults into account in the earthquake-resistant design of their power plants.

The Japanese government intends to evaluate faults also in other regions of the country, in order to update the existing list. Their plan is to increase awareness of local people against earthquake hazard and promote the updated list to local governments for inclusion in their disaster prevention strategies.