Geoscience Reference
In-Depth Information
Appendix 10
The Modified Mercalli Intensity Scale
(abridged version)
I . Not felt except by a very few under especially favourable conditions.
II .Felt only by a few persons at rest, especially on upper floors of buildings.
III .Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many
people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations
similar to the passing of a truck.
IV .Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes,
windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking
building. Standing motor cars rocked noticeably.
V .Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects
overturned.
VI .Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen
plaster. Damage slight.
VII . Damage negligible in buildings of good design and construction; slight to moderate in
well-built ordinary structures; considerable damage in poorly built or badly designed
structures; some chimneys broken.
VIII . Damage slight in specially desinged structure; considerable damage in ordinary
substantial buildings with partial collapse. Damage great in poorly built structures. Fall of
chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
IX . Damage considerable in specially designed structures; well-designed frame structures
thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings
shifted off foundatins. Underground pipes broken.
X . Some well-built wooden structures destroyed; most masonry and frame structures
destroyed with foundations. Rails bent.
XI .Few,ifany (masonry) structures remain standing. Bridges destroyed. Rails bent greatly.
XII . Damage total. Waves seen on ground surface. Lines of sight and level are distorted.
Objects thrown into the air
654
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