That is, an overprinting of the following image onto itself having been rotated 90 degrees.
It's an odd geometric fact that the rotation about the centre of the image creates these apparent diamonds from straight lines.
In this second attempt, the same lines are used but as well as being rotated they are shifted up by an amount which causes their left ends to coincide.
Whether or not you get the Moire effect depends partly on the quality of the images as uploaded here and also on the interference from the pixels on your screen. I've looked at these images in their original size on an HD screen and by zooming in/out managed to get quite interesting effects. The images here, viewed on the same screen are effective, but not quite so versatile. On the retina display of the iPad they are OK and on the same disply on the iPhone just about satisfactory.
If you want to play with a higher definition image, and are prepared to download a 7MB file, the first image is reproduced here as a 7000*5000 jpeg.
There is a video made from the same lines used in the first image on vimeo at https://vimeo.com/58101115.