The facility has been under various levels of renovation since 2004 when the oldest imagery dates from. Between 2004 and 2007 the compound remains roughly the same with only minor changes. It should be noted that the suspected static missile test site 2 km south of this compound was first built somewhere between 2004 and 2007, and only completed. In 2009 construction escalates; the fact that the landfill is in use confirms the construction happening during that time. In 2010 the first blue-roofed buildings emerge; speaking broadly, the use of blue roofing material has become more common recently and is often associated with industrial military buildings (for other examples of this, look to the IRGC's HSPB factory in Bandar Abbas, or the suspected IRGC engineering buildings adjacent to the 77th mechanized infantry division's headquarters in Mashhad). A number of new trees have been planted near the northern buildings and they have a more lived-in appearance. By June 2011 several new buildings have been erected near the entry-point as well as additions onto the pre-existing garages and workshops. Paved areas have also been expanded around these workshops. Not much changes by September of 2011 except for the apparent completion of construction on the same additions. There are also what appear to be, possibly, large tanks for holding liquids.
[EDIT: The picture below isn't the proper size, fixing sometime soon]
|Construction from 2004-2011|
Looking at the imagery provided by ISIS (see hyperlink above), the blast appears to have originated in the western-half of the compound, likely from the two bottom-most workshops on the western side. Both of these buildings have been completely annihilated as has the blue-roofed building north of these garages. Several of the administrative buildings bordered with trees have also been destroyed, but it's unlikely the explosion originated from either of these buildings and it's more likely they were damaged and later demolished in the cleanup. The four other workshops all suffered significant damage though are still standing.