Alcubierre Drive & Gravitational Waves: Alien Effects?

[Grasshopper]

TL;DR

If alien people used an Alcubierre drive, would it create notable gravitational waves?

Suppose some aliens travel to our solar system after seeing our radio broadcasts using an Alcubierre drive. Would it not create a notable gravitational disturbance? Or does it leave spacetime undisturbed around it?

 

[PeterDonis]

As far as I know there are no gravitational waves in an Alcubierre spacetime.

 

[Grasshopper]

Thanks