Structural Components and Systems

For The Seismic Retrofit of Tilt-up Buildings

Modified Mercalli Scale Intensity

 

Modified Mercalli Scale and PGA

MMI
PGA (g)
IV
0.03 and below
V
0.03 - 0.08
VI
0.08 - 0.15
VII
0.15 - 0.25
VIII
0.25 - 0.45
IX
0.45 - 0.60
X
0.60 - 0.80
XI
0.80 - 0.90
XII
0.90 and above

The above table shows the approximate relationship between Modified Mercalli Intensity and Peak Ground Acceleration (PGA).

 

Richter Magnitude, PGA, and Duration

Richter Magnitude
PGA (g)
Duration (seconds)
5.0
0.09
2
5.5
0.15
6
6.0
0.22
12
6.5
0.29
18
7.0
0.37
24
7.5
0.45
30
8.0
0.50
34
8.5
0.50
37

The above table shows the approximate relationship between Richter Magnitude, Peak Ground Acceleration (PGA), and duration of strong-phase shaking near the epicenter of earthquakes located in California.