CHINA

1. Unit to express the size of an earthquake

Vibration Frequency

Vibration frequency is the measurement of the number of cycles that occur per second. The main frequency component of earthquake is less than 10Hz and its vertical wave has higher frequency than horizontal wave.

Acceleration

Unit to express the acceleration of earthquake is *Gal.
980Gal=980cm/s²≒1G
So called "Mega-earthquake" once occured in Japan; Hanshin, Chuetsu and Tohoku recorded the waveform of more than 1000Gal and it was clear that the acceleration was bigger than a gravitational acceleration (1G) generated in these quakes.

Unit of acceleration, 1Gal=1cm/s², and widely used in the field of seismology.
"Gal" is categorized as non SI (international unit) with limitation. However, it is allowed to be used freely in gravitational acceleration or earthquake related matters.

Magnitude

Magnitude is the measure of an earthquake size from the focus. Generally, the deeper and larger the magnitude is, the more the vibration spreads.

Seismic Intensity Scale in Japan

At present, Japan Meteorological Agency use Shindo to measure the intensity of an earthquake.
The Seismic Intensity Scale is calculated based on the ground acceleration waveform.
The Seismic Intensity Scale may change after the calculation according to the earthquake duration and vibration.

Seismic Scale in Other Countries

The value the JMA established was re-evaluated after the Great Hanshin/Awaji earthquake. It is classified into 10 scales; 0-4・5-lower・5-upper・6-lower・6 upper・7.
Each country uses a different seismic scale .

【See chart】

-1000	7	X XI XII	XI XII	VII	Thrown by the shaking and impossible to move at will.	Water and electric supplies may stop over wide areas.
	6-upper		X		Impossible to keep standing and impossible to move at all.	Gas pipeline to the local district and water distribution facility are damaged.
-500	6-lower				Difficult to keep standing.	Gas supply pipelines to the household and major water pipes are damaged.	400Gal: Stop all the power supply in the factory.
-400		IX
-300			IX	VI			250Gal: Emerfency call for evacuation. Shut down the dangerous gas pipeline (explosive, lethal)
	5-upper				Many people are considerably frightened and find it diffucult to move.	Gas supply pipelines to the household and major water pipes are damaged.	150Gal: Go on a patrol thoroughly to check the situation of damage of all equipment from all departments.
				V
-200		VIII
			VIII
	5-lower				Most people try to escape from danger by running outside.	Gas meter with safety devices are tripped, stopping the supply of gas in same household. In rare cases, suspension of water supply may occur.	100Gal: Go on patrol to check if there is an abnormal condition in important equipment.
					Some people find it difficult to move.		80Gal: Evacuation call. Emergency stop for the part of equipment. Shutdown part of lifeline.
-100			VII
		VII
				IV
	4				Many people are frightened. Some people try to escape from danger.	-	40Gal: Make an announcement of earthquake scale. Evacuation call if necessary. Check if there is an abnormal condition equipment by going on a quick patrol.
-50			VI
-30		VI			Most sleeping people awake.
	3				Felt by many to all people indoors.	-	8Gal: Make an announcement of earthquake scale. No need to evacuate. Check if there is an abnormal condition in equipment by going on a quick patrol.
			V	III
-20		V
					Some people are frightened.
			IV
-10		IV
	2				Felt by many people indoors.	-	-
-5				II
		III	III
					Some people awake.
-3				I
-2	1				Felt by only some people indoors.	-	-
		II	II
-1		I
	0		I	0	Not felt by all or most people.	-	-
Reference Acceleration (GAL)	JMA Seismic Intensity in 1996	Modified Mercalli Intensity in 1956	M.S.K Intensity. in 1964	Taiwan Seismic Intensity in 2000	Human perception and reaction	Utilities and Infrastructure	Reference Example of Alarm Output in Japan

**Note: Information on this chart is only for reference.