How to Measure an Earthquake
The Modified Mercalli Scanle
Degree of Damage
The Richter Scale

1-4 Instrumental

to Moderate

No damge < /=4.3
5 Rather Strong Damage negligible 4.4 - 4.8
6 Strong Damage slight 4.9 - 5.4
7 Very Strong Damge slight to moderate in well-built structures 5.5 - 6.1
8 Destructive Structural damage considerable 6.2 - 6.5
9 Ruinous Structural damage severe, some will collapse 6.6 - 6.9
10 Disasterous Most massorry and frame structures /foundations destroyed 7.0 -7.3
11 Very Disasterous Few or no masonry structures remain standing 7.4 - 8.1
12 Catastrophic Damage nearly total > 8.1