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Nepal Hazard Risk Assessment
2.4 MODEL FOR CONVERTING PGA TO MMI
Conversion of PGA to MMI is started by using table result from PSHA analysis as main input. This grid
file is then plotted to map and interpolated to produce PGA map, as seen in Figure 2.13. The PGA then
is converted to gals unit that resulted as PGA100 output. The PGA100 is the main intermediate input for
converting to MMI. Based on several equation:
MMI Trifunac 1 log 980 0.014
0.3
MMI Wald 2.20 log 1.00
MMI Wald, 5M 3.6 log 1.66
PGA100 is converted to MMI. The result showed that Trifunac method has higher MMI value compared
to Wald. Trifunac value peaked in around 9.2 while Wald peaked in 8.7 MMI.
Figure 2.11. Peak Ground Acceleration in Nepal 100 year return period.
Figure 2.13. Flowchart of converting PGA to MMI
Figure 2.12. Peak Ground Acceleration in Nepal 50 year return period
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