After much Googling, the matter is unclear. If the site was shifted, it happened in 2007 - I found 2006 images that show just the original site. All 2007 overhead images appear to be based on what’s in Google Earth (or Google Maps) which may or may not be correct.
I have a friend who has been there the past 5 years or so - I’ll try to contact him and see if he can sort this out.
Fine. Salt. To rephrase the question then: why is the ground dusky yellow/brown when you zoom in, and brilliant white when you zoom out?
My friend reports that the location did shift - in 2006. The dual image is misleading, though - essentially every trace of the former site was removed. Indeed, it appears this is done each year, as part of the arrangement with the BLM (or whoever it is that controls the land on which the festival is held).