Intensity Measure (IM)
An Intensity Measure is an attribute of earthquake shaking that is useful for predicting damage or loss. It is defined by an:
An IMT specifies the particular type of Intensity Measure. IMTs currently implemented in OpenSHA include:
- Peak Ground Acceleration (PGA)
- Peak Ground Velocity (PGV)
- Peak Ground Displacement (PGD)
- Spectral Acceleration (SA)
- Modified Mercalli Intensity (MMI)
OpenSHA was designed so that virtually any other IMT may be defined and implemented. For example, a new IMT might be composed of a vector of traditional IMTs.
An IML specifies the level, or value, of the IMT that one is concerned about exceeding. For example, one might want to know that probability that Peak Ground Velocity (the IMT) will exceed a level of 100 cm/sec (the IML).