With this tutorial, we will be working photos of dried cracked mud, so go to google images and search for "dried mud". It works best on pictures with birds eye view (direct view from top) so we can see the cracks. Alternatively, you can use any of the images below. (Click to get larger size). Please note that the steps may differ if your image is significantly different to the one im using in this tutorial, so experiment :)

I'll be working on the 2nd image. Base on that image, I start a new document 640x480.

Now open the mud image up, on the dirt image, do a CTRL+A to select all, then go to the new document you just created and press CTRL+V to paste the image.

The cracks are dark, so we'll invert the image so it becomes white, this will give it a better explosion effect. so go to Image->Adjustment->Invert (or press CTRL+I).

Now use the eliptical marquee tool and make a large round selection on the image. Hold SHIFT while you create the selection to make a perfect round circle.

Click to view larger image

Now go to Select->Inverse,
Then hit Delete so you are left with a circle from the mud image. DO NOT DESELECT YET.

Click to view larger image

Now, while you still got your selection, go to SELECT->INVERSE again to select the shape.

Now go to Filter->Distort->Spherize. Set amount to 100%. Then do it again, this time, 50%. You can now deselect.

Now, lets fill the background layer (the layer underneath the mud layer) with black.

Then go to Layer->Flatten Image

Now go to Filter->Sharpen->unsharp Mask.
Amount: 500%. Radius: 1.7px. Threshold: 122 levels

- Go to Filter->Distort->Polar Co-ordinates.
Options: Polar to Rectangular. VIEW

Go to: Image->Rotate Canvas->90CW. VIEW

Apply: Filter->Stylize->Wind
Method: Wind. Direction: From the right. Hit CTRL+F to reapply. VIEW

Go to: Image->Rotate Canvas->90CCW. VIEW

Finally, apply Filter->Distort->Polar Coordinates.
Options: Rectangular to Polar.

There you go, now all you do is just play around with colors, by either using Image->Hue and Saturation, or Image->Color Balance.
I use color balance in the image below.

This tutorial will work for basically and image with textures such as cracks. Here are a few variations.
Before                   ----->                        After.