Japan Meteorological Agency seismic intensity scale

The JMA scale (Japanese気 象 庁 震 度 阶级, Kisho -chō shindo kaikyū, dt " earthquake magnitude classes according to Japan Meteorological Agency ( JMA ) " ) is that of the JMA and the Taiwanese CWB (Central Weather Bureau ) used intensity scale for earthquakes.

A first scale with four levels of intensity was developed in 1884 by the JMA. After several extensions in 1951 elaborated on the basis of the 1900 developed by Fusakichi Omori Ōmoriskala a new scale of the JMA, the seven levels based on limits for the maximum ground acceleration. Since 1996, the JMA will now use the scale in its present form.

Unlike magnitude scales, such as the frequently quoted Richter scale, describe intensity scales such as the JMA scale, the EMS scale or the Mercalliskala the effects of an earthquake on the surface and can therefore for a single earthquake at different locations reflect different strengths. They should therefore not be confused with magnitude scales, especially not with the JMA magnitude scale.

In earthquake in Japan, the earthquake are now being detected based on automatic measurements and the intensity determined by the frequency filtered accelerations and " measured earthquake magnitude " into a (计 测 震 度, Keisoku shindo ) to be converted. The calculated values ​​are transmitted according to defined limits on the JMA scale. Then next to the Magnitude cards with intensities for all stations are published by the JMA (and stronger quake addition of the mass media).

The individual steps ( shindo kaikyū ) of the JMA scale are described as follows: