# liquefaction.crr_m75()

Cyclic resistance ratio at the magnitude 7.5 reference and 1 atm.

Usage

[Source](https://github.com/lornearnold/driven-pile/blob/main/src/driven_pile/liquefaction.py#L45-L63)

``` python
liquefaction.crr_m75(n160cs)
```

## Parameters

`n160cs: array_like`  
Clean-sand equivalent blow count.

## Returns

`ndarray`  
`exp(N/14.1 + (N/126)**2 - (N/23.6)**3 + (N/25.4)**4 - 2.8)`.

## References

Boulanger and Idriss (2014), Eq. 2.25.