Table 3: Faults, Thermal
Waters, Seismicity
Modified Mercalli Intensity Scale of 1931
(abridged)
RATING | DESCRIPTION |
I | Not felt except by a very few under especially favorable circumstances. |
II | Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. |
III | Felt quite noticeably indoors, especially on upper floors of buildings, but many people did not recognize it as an earthquake. Standing motor cars may rock slightly. Duration estimated. |
IV | During the day felt indoors by many, outdoors by few. At night some awakened. Dishes, windows, doors disturbed, walls made cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. |
V | Felt by nearly everyone; many awakened. Some dishes, windows, etc., broken; a few instances of cracked plaster; unstable objects overturned. Disturbance of trees, poles, and other tall objects sometimes noticed. Pendulum clocks may stop. |
VI | Felt by all; many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster or damaged chimneys. Damage slight. |
VII | Everybody runs outdoors. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving motor cars. |
VIII | Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse; great in poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. Sand and mud ejected in small amounts. Changes in well water. Persons driving cars disturbed. |
IX | Damage considerable in specially designed structures; well designed frame structures thrown out of plumb; great damage in substantial buildings, with partial collapse. Buildings shifted off foundations. Ground cracked conspicuously. Underground pipes broken. |
X | Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundation, ground badly cracked. Rails bent. Landslides considerable from river banks and steep slopes. Shifted sand and mud. Water splashed (slopped) over banks of rivers, canals, etc. |
XI | Few if any (masonry) structures remain standing. Bridges destroyed. Broad fissures in ground. Underground pipe lines completely out of service. Earth slumps and land slips in soft ground. Rails bent greatly. |
XII | Damage total. Waves seen on ground surfaces. Lines of sight and level distorted. Objects thrown upward into the air. |