I am art impaired, so this is mainly blue nodes.
No vegs.
Start with a fractal landscape.
Add a generous amount of offset, ensure no negative displacement.
Create a B&W soft irregular mask (limited radius) with a center in front the camera.
Black in the center, white or gray at outside the radius.
multiply with a "displacement shader to scalar".
Subtract this from the fractal landscape (a displacement shader)
