Yeah, that's a pool of magma over a thousand kilometers across, surrounded by lines of active volcanoes. The fictional bomb described here uses hypothetical (and possibly nonexistent) properties of strangelets.
P.S. Congratulations to the Indian space program for their launch of the Chandrayaan-1 probe to the Moon. The probe will orbit the Moon for two years, mapping it to a five meter resolution and mapping the abundance of a number of elements, among other experiments.
Tried some slightly different shading techniques and a #6HB pencil today. Didn't come out too badly. About those sentence fragments.
Hmm, we were goofing on Wikipedia a few days ago, which strongly indicates to me that I should link you to Desmond Warzel's Wikihistory.