foundation system of burj al arab

Modified Mercalli Seismic Intensity Scale

Intensities portray the effects of an earthquake in a particular location. These effects include potential damage, perception of shaking and permanent changes in topography. The most popular intensity scale used in the United States is the Modified Mercalli Scale (MMI) first developed in 1931.



MODIFIED MERCALLI INTENSITY SCALE 
MMI Value
Full Description
I
People do not feel any earth movement.
II
Felt by persons at rest, on upper floors of tall buildings 
III
Felt by people indoors.  Hanging objects swing back and   forth. 
Vibration from the earthquake may seem like the passing of light 
trucks. May not be recognized as an earthquake.
IV
Hanging objects swing.  Vibration may seem like   the   passing 
of heavy  trucks  or  a jolt, like  a  heavy  ball striking  the walls.   
Parked vehicles may  rock noticeably. Windows, dishes, doors 
may rattle and glasses clink.  In the upper range of IV, walls of 
wood frame buildings may creak.  
V
Almost everyone feels movement whether inside or outdoors. 
Sleeping  people  are  awakened.  Liquids  in  containers  are 
disturbed;    some  are  spilled.  Small   unstable  objects  are 
displaced   or   overturned. Doors   swing,   close,  or   open.   
Shutters, pictures on the wall move. 
VI
Almost everyone feels movement whether inside or outdoors. 
Sleeping   people  are  awakened.  Liquids  in containers are 
disturbed;   some are   spilled.  Small   unstable  objects  are 
displaced   or   overturned.  Doors  swing,  close,   or  open.   
Shutters, pictures on the wall move. 
VII
People  have  difficulty  standing. Drivers   on   the  road feel 
their cars shaking. Furniture  may  be  overturned and broken. 
Loose bricks fall from buildings and masonry walls and cracks 
in plaster   and  masonry  may  appear.  Weak chimneys may 
break at the roofline.  Damage  is  slight  to  moderate in well-
built structures; considerable in  poorly  constructed  buildings 
and facilities.
VIII
Drivers have trouble steering. Tall   structures such as towers, 
monuments  and  chimneys   may  twist and fall. Wood frame 
houses  that  are not bolted to their foundations may shift and 
sustain  serious  damage.  Damage   is   slight to  moderate in 
well-constructed buildings,considerable in poorly constructed 
buildings. Branches are broken  and  fall from trees. Changes 
occur in flow or  temperature  of   springs and  wells. Cracks 
appear in wet ground and on steep slopes. 
IX
Masonry  structures  and  poorly  constructed  buildings suffer
serious  damage  or  collapse.  Frame  structures, if not bolted, 
shift   off     foundations.     Serious   damage    to    reservoirs.   
Underground    pipes    broken.  Conspicuous  cracks  in   the   
ground. In  alluvial  areas, sand  and   mud  ejected  and  sand 
craters are formed.
X
Most masonry and frame   structures  destroyed   along   with 
their foundations.  Some   well-built  wooden   structures  and 
bridges are destroyed.    Serious  damage   to   dams,   dikes, 
and embankments. Large   landslides   occur.  Water  thrown 
on the banks of canals,  rivers   and  lakes.  Sand   and   mud 
shift horizontally on beaches and flat land.  Rails bent. 

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