My guess would be that someone converted a survey into contours but the contours information was in other units (meters?) than the ground plane (millimeters?). Perhaps the model should be scaled 1000 (or 100 or 10) times in the blue direction?
Edit: As the model is so flat that the Scale tool in SketchUp doesn’t show the blue scaling grip, I had to try it in AutoCad.
When I scaled it 10 000 times in the vertical direction the vertical distance of the contour lines became 100 mm in SketchUp. What should it be? The file seems to have a couple of errors that show as steep peaks or abysses in the scaled version
I attach the skp below but I had to zip it as it is about 4 MB. For a SketchUp terrain, I would guess that at least half of the contours could be deleted, it is far too fine-grained. To me it seems that it was somehow auto-generated with some software out of a relatively small number of actual survey points.
If the horizontal unit also should be Centimeters, you will still have to scale it 10 times in the red/green direction. Then the site would measure some 2 kilometers across (it is now about 200 meters)
terrain.zip (1.4 MB)