EXPLANATORY TABLE
ON THE JAPAN METEOROLOGICAL AGENCY (JMA)
SEISMIC INTENSITY SCALE

(February 1996)

Seismic intensity provides a measure of the strength of seismic ground motion. It is observed with a seismic intensity meter. This table describes the situations and damage that may be caused by seismic ground motion of each seismic intensity. When using this table, please note the following:
(1)The seismic intensity announced by JMA is a value obtained with a seismic intensity meter, and is not determined from observed phenomena described in this table.

(2)Sites where equal seismic intensities were observed did not necessarily suffer the same degree of damage, since damage depends on the type of construction used and on the nature of the seismic ground motion. This table describes some typical situations which may appear. More or less damage than that described in the table may occur.

(3)Seismic ground motion are greatly influenced by ground and topography. Seismic intensity is a value observed at a site where a seismic intensity meter is installed. Seismic intensity occasionally varies even within a city. Seismic intensity is usually measured on the ground surface, so in general, the shaking on upper stories of buildings may be amplified greatly.

(4)A large earthquake generates long-period seismic waves. Even at locations far from the epicenter, where the seismic intensity is rather small, the long-period waves may occasionally cause unusual types of damage, such as the sloshing of oil in a tank or troubles with elevators.

(5)This table is prepared based mainly on the examples collected from recent destructive earthquakes. The table is subject to revision when new examples are collected or the present descriptions become inconsistent with actual situations, due to the improvement of earthquake resistant buildings, etc.


Instrumental Seismic Intensity JMA Seismic Intensity Scale People Indoor situations Outdoor situations Wooden houses Reinforced-concrete buildings Basic infrastructure Ground and slopes
  0 Imperceptible to people.            
0.5                
  1 Felt by only some people in the building.            
1.5                
  2 Felt by many people in the building. Some sleeping people awakened. Hanging objects such as lamps swing slightly.          
2.5                
  3 Felt by most people in the building. Some people are frightened. Dishes in a cupboard rattle occasionally. Electric wires swing slightly.        
3.5                
  4 Many people are frightened. Some people try to escape from danger. Most sleeping people are awakened. Hanging objects swing considerably and dishes in a cupboard rattle. Unstableornaments fall occasionally. Electric wires swing considerably. People walking on a street and some people driving automobiles feel the tremor.        
4.5                
  5Lower Most people try to escape from 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 swaying. Occasionally, window panes 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. Rock falls and small slope failures take place in mountainous districts.
5.0                
  5Upper Many people are very 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. Some doors get unhinged. In many cases, unreinforced concrete-block walls collapse and tombstones overturn. Many automobiles come to a stop because it becomes difficult to drive. Occasionally, poorly installed vending machines fall over. Occasionally, less earthquake-resistant houses suffer heavy damage to walls and pillars and lean to one side. Occasionally, large cracks are formed in walls, crossbeams and pillars of less earthquake-resistant buildings, and even highly earthquake-resistant buildings develop 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. Rock falls and small slope failures take place in mountainous districts. 
5.5                
  6Lower Difficult to keep standing. A lot of heavy and unbolted furniture moves and falls, it is impossible to open the door in many cases. In many 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 develop 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 and slope failures take place in mountainous districts.
6.0                
  6Upper Impossible to keep standing or to move without crawling. Most heavy and unbolted furniture moves and falls. Occasionally, sliding doors are thrown out of their grooves. 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 heavily 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 and slope failures take place in mountainous districts. 
6.5                
  7 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 houses are severely damaged and lean to one side. Occasionally, even highly earthquake-resistant buildings are severely damaged and lean to one side. [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 local topographic features.


* The descriptions given in [ ] of "Basic infrastructure" describe situations concerning gas, water and electrical service in particular.