# Dictionary:Instantaneous q factor

The instantaneous quality (Q) factor is a seismic attribute and is the ratio of instantaneous frequency to twice the instantaneous bandwidth.This Q computation is the short wavelength variation of the Q value, therefore, it gives relative values. ^{[1]}

Where is the instantaneous decay rate, which is defined as the *first derivative of the trace envelope* divided by the *trace envelope* envelop providing an expression:

Where is the *instantaneous frequency* while is the *trace envelope* and is the *first derivative of the trace envelope*.It is also a physical attribute with a strong relation to porosity, permeability, and fracture.

- Indicates local variation of Q factor, similar to the relative acoustic impedance computation from the seismic trace. Longer wavelength variation should be computed by spectral division and added to this attribute.
- May indicate liquid content by rationing pressure versus shear wave section Q factors.
- Indicates relative absorption characteristics of beds.
- It is a transmissive attribute; its various wavelength components should be estimated in a similar way to the average velocity and velocity inversion procedures.

## References

- ↑ Taner, Turhan (1992), Attributes Revisited, Rock Solid Images Houston, Texas (published 2000)

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