The Mercalli Scale

Richter Magnitude Mercalli Intensity Scale Description Explanation
1.0 - 2.9 I Instrumental Not felt by many people unless in favourable conditions.
3.0 -3.4 II Weak Felt only by a few people at best, especially on the upper floors of buildings. Delicately suspended objects may swing.
3.5 -3.9 III Slight Felt quite noticeably by people indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.
4.0 - 4.4 IV Moderate Felt indoors by many people, outdoors by few people during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rock noticeably. Dishes and windows rattle alarmingly.
4.5 - 4.9 V Rather Strong Felt outside by most, may not be felt by some outside in non-favourable conditions. Dishes and windows may break and large bells will ring. Vibrations like large train passing close to house.
5.0 - 5.4 VI Strong Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books fall off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight.
5.5 - 5.9 VII Very Strong Difficult to stand; furniture broken; damage negligible in building 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. Noticed by people driving motor cars. I hope you have adequate insurance! Possible need for temporary business relocation.
6.0 - 6.4 VIII Destructive Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved. I hope you have adequate insurance! Possible need for temporary business relocation.
6.5 - 7.9 IX Violent General panic; 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 foundations. 40% of small business will not reopen. I hope you have adequate insurance!
8.0 - 8.4 X Intense Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent. I hope you have adequate insurance!
8.5 - 9.9 XI Extreme Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly. I hope you have adequate insurance!
10.0 - 10.4 XII Cataclysmic Total destruction - Everything is destroyed. Lines of sight and level distorted. Objects thrown into the air. The ground moves in waves or ripples. Large amounts of rock move position. Landscape altered, or leveled by several meters. In some cases, even the routes of rivers are changed. Earthquake insurance provides you with the means to rebuild no matter how bad the damage. Get it today!




Depending on the intensity of an earthquake, distance from the epicenter, and the construction of your building, your business could be in jepordy. 40% of small businesses never open their doors afte a major disaster such as an earthquake. Take a look at our modified Mercalli Scale to get an underdstanding of the potential damage your building could incur. According to the U.S. Geological Survey, there is a 70 percent probability that one or more damaging earthquakes of magnitude 6.7 or larger will strike the San Francisco Bay area during the next 30 years. (A magnitude 6.7 earthquake is equivalent to the 1994 Northridge, Calif., earthquake that killed 57 people and caused $20 billion worth of damage.)

Yet, only 88% of Californians have earthquake insurance .