Intensity Measure

Intensity Measure

Any attribute of earthquake shaking that is useful for predicting damage or loss.

Intensity Measure Type (IMT) specifies the particular type of attribute.

Currently implemented IMTs include:

Peak Ground Acceleration (PGA)
Peak Ground Velocity (PGV)
Peak Ground Displacement (PGD)
Spectral Acceleration (SA)
Modified Mercalli Intensity (MMI)

We have designed so that virtually any other IMT could be defined and implemented in the OpenSHA framework (without rewriting existing code). For example, a new IMT might be composed of a vector of traditional IMTs.

Intensity Measure Level (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).

For example, one might conduct a Seismic Hazard Analysis to determine the probability that Peak Ground Acceleration (the IMT) will exceed 0.5 g (the IML).