Use masks and blurs in conjunction with the Extrude Filter to create the illusion of a planetary collapse.
- Difference Clouds
- Radial Blur
- Layer Mask
Create a new image 500x500px with a "transparent" background. Press D to reset the Color Palette. Rename the existing layer "color land"
Render some Clouds ( Filter > Render > Clouds ). Next, render Difference Clouds ( Filter > Render > Difference Clouds ) four times. Do this by using the top menu to execute the Difference Clouds filter once, then pressing Ctrl-F 3 times to repeat the last filter (in this case Difference Clouds) three times.
Invert ( Ctrl-I or Image > Adjustments > Invert ) the colors of the image.
Select layer "blast land" on the Layer Palette and give it a Radial Blur ( Filter > Blur > Radial Blur ) with the settings shown in the image.
Add a Layer Mask to layer "blast land" by clicking on the "add layer mask" button on the bottom of the Layer Palette.
Click on the Gradient tool and choose the "Radial Gradient". Check "Reverse". Click the middle of the image and drag out to the corner of the image to make a nice black to white circle gradient in your layer mask.