Japan Meteorological Agency seismic intensity scale

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The Japan Meteorological Agency seismic intensity scale is a measure used in Japan and Taiwan to indicate the strength of earthquakes. It is measured in units of shindo (震度, shindo^? seismic intensity, literally "degree of shaking"). Unlike the Richter magnitude scale (which measures the total magnitude of the earthquake, and represents the size of the earthquake with a single number) the JMA scale describes the degree of shaking at a point on the Earth's surface. As a result, the measure of the earthquake varies from place to place, and a given quake may be described as "shindo 4 in Tokyo, shindo 3 in Yokohama, shindo 2 in Shizuoka".

The JMA operates a network of 180 seismographs and 600 seismic intensity meters^[1] and provides real-time earthquake reports to the media and on the internet.^[2]

1 History
2 JMA scale explanation
3 See also
4 References
5 External link

[edit] History

It is told that nation wide Japan has approx. 400 time ^[3]of earthquake in everyday when counts from shindo scale "0" or less detectable by apparatus which is imperceptible to people. Having earthquake so frequently, JMA set four scale Shindo, 微 (faintly), 弱 (weak), 強 (strong), 烈 (furious) with simple description in 1884 and used till 1897. In 1898 four scale is further expanded to 0-6, 7 scales. In 1908, these 7 scale is fully described with literary language widely used since Meiji period, and in 1936-1948 scale description is revised to vernacular fashion used in early Shōwa period. Shindo had been derived by expert in JMA, however after Great Hanshin earthquake in 1995, Shindo further expanded to 10 scales, 0-4, 5 lower/upper, 6 lower/upper and 7 and Shindo scale has been began to measured by seismic intensity meter from 1996.^[4]^[5]

[edit] JMA scale explanation

The JMA Scale runs from 0 to 7, with 7 being the strongest that set in February 1996. Sometimes roman numerals are used, as in the Mercalli intensity scale; however this is not the usual practice in Japan. The real-time reports are calculated automatically from measurements of ground acceleration. The JMA reports the shindo based on the ground acceleration, measured automatically with seismic intensity meters since 1, April 1996.

Shindo scale ^[6]
Magnitude-Shindo Number (Shindo Number in Japanese) / Meter reading	People	Indoor situations	Outdoor situations	Wooden houses	Reinforced-concrete buildings	Lifelines	Ground and slopes	Peak ground acceleration
0 (0) / 0-0.4	Imperceptible to people.							Less than 0.008 m/s²
1 (1) / 0.5-1.4	Felt by only some people in the building.							0.008–0.025 m/s²
2 (2) / 1.5-2.4	Felt by most people in the building. Some people awake.	Hanging objects such as lamps swing slightly.						0.025–0.08 m/s²
3 (3) / 2.5-3.4	Felt by most people in the building. Some people are frightened.	Dishes in a cupboard rattle occasionally.	Electric wires swing slightly.					0.08–0.25 m/s²
4 (4) / 3.5-4.4	Many people are frightened. Some people try to escape from danger. Most sleeping people awake.	Hanging objects swing considerably and dishes in a cupboard rattle. Unstable ornaments fall occasionally.	Electric wires swing considerably. People walking on a street and some people driving automobiles notice the tremor.					0.25–0.80 m/s²
5-lower (5弱) / 4.5-4.9	Most people try to escape from a danger. Some people find it difficult to move.	Hanging objects swing violently.Most Unstable ornaments fall. Occasionally, dishes in a cupboard and books on a bookshelf fall and furniture moves.	People notice electric-light poles swing. Occasionally, windowpanes are broken and fall, unreinforced concrete-block walls collapse, and roads suffer damage.	Occasionally, less earthquake-resistant houses suffer damage to walls and pillars.	Occasionally, cracks are formed in walls of less earthquake-resistant buildings.	A safety device cuts off the gas service at some houses. On rare occasions water pipes are damaged and water service is interrupted. (Electrical service is interrupted at some houses)	Occasionally, cracks appear in soft ground. and rockfalls and small slope failures take place in mountainous districts.	0.80–1.40 m/s²
5-upper (5強) / 5.0-5.4	Many people are considerably frightened and find it difficult to move.	Most dishes in a cupboard and most books on a bookshelf fall. Occasionally, a TV set on a rack falls, heavy furniture such as a chest of drawers falls, sliding doors slip out of their groove and the deformation of a door frame makes it impossible to open the door.	In many cases, unreinforced concrete-block walls collapse and tombstones overturn. Many automobiles stop because it becomes difficult to drive. Occasionally, poorly-installed vending machines fall.	Occasionally, less earthquake-resistant houses suffer heavy damage to walls and pillars and lean.	Occasionally, large cracks are formed in walls, crossbeams and pillars of less earthquake-resistant buildings and even highly earthquake-resistant buildings have cracks in walls.	Occasionally, gas pipes and / or water mains are damaged.(Occasionally, gas service and / or water service are interrupted in some regions)	Occasionally, cracks appear in soft ground. and rockfalls and small slope failures take place in mountainous districts.	1.40–2.50 m/s²
6-lower (6弱) / 5.5-5.9	Difficult to keep standing.	A lot of heavy and unfixed furniture moves and falls. It is impossible to open the door in many cases.	In some buildings, wall tiles and windowpanes are damaged and fall.	Occasionally, less earthquake-resistant houses collapse and even walls and pillars of highly earthquake-resistant houses are damaged.	Occasionally, walls and pillars of less earthquake-resistant buildings are destroyed and even highly earthquake-resistant buildings have large cracks in walls, crossbeams and pillars.	Gas pipes and / or water mains are damaged.(In some regions, gas service and water service are interrupted and electrical service is interrupted occasionally.)	Occasionally, cracks appear in the ground, and landslides take place.	2.50–3.15 m/s²
6-upper (6強) / 6.0-6.4	Impossible to keep standing and to move without crawling.	Most heavy and unfixed furniture moves and falls. Occasionally, sliding doors are thrown from their groove.	In many buildings, wall tiles and windowpanes are damaged and fall. Most unreinforced concrete-block walls collapse.	Many, less earthquake-resistant houses collapse. In some cases, even walls and pillars of highly earthquake-resistant houses are heavy damaged.	Occasionally, less earthquake-resistant buildings collapse. In some cases, even highly earthquake-resistant buildings suffer damage to walls and pillars.	Occasionally, gas mains and / or water mains are damaged.(Electrical service is interrupted in some regions. Occasionally, gas service and / or water service are interrupted over a large area.)	Occasionally, cracks appear in the ground, and landslides take place.	3.15–4.00 m/s²
7 (7) / 6.5- up	Thrown by the shaking and impossible to move at will.	Most furniture moves to a large extent and some jumps up.	In most buildings, wall tiles and windowpanes are damaged and fall. In some cases, reinforced concrete-block walls collapse.	Occasionally, even highly earthquake-resistant buildings are severely damaged and lean.	Occasionally, even highly earthquake-resistant buildings are severely damaged and lean.	(Electrical service gas service and water service are interrupted over a large area.)	The ground is considerably distorted by large cracks and fissures, and slope failures and landslides take place, which occasionally change topographic features.	Greater than 4 m/s²

[edit] See also

[edit] References

^ 気象庁 | 震度観測点（全国）
^ Japan Meteorological Agency | Earthquake Information
^ http://www.hinet.bosai.go.jp/about_earthquake/part1.htm Japanese web site; official data of Shindo 1-7 in 1997 to 2006 is 32,244 times, and Shindo 1-3 is 4 to 5 times in a day. Web site of 防災科学技術研究所;National Research Institute for Earth Science and Disaster Prevention=NIED/ Although none of web site is available for basis of 400 times in a day, but 400 times is well told and well assumable number with this data.
^ 気象庁震度階級（明治17年～昭和23年）in Japanese
^ 震度 in Japanese
^ JMA seismic intensity scale

[edit] External link

Up dating information of earth earthquakes in Japan in last 7 days, Japanese language. Circled number is Shindo(震度) Number.　Format is Hypocenter of earthquakes, location, north latitude, east longitude and depth.