Landing lines??

I know many people will groan at yet another Google Earth snapshot.. but when browsing over A51 I noticed these circular lines on approach to each of the runways. Just wanted to know if anyone can shed any light on any of them or if they are just some form of landing apparatus..

Pics:

There has already been several threads about this topic. These are known as "The Hook" and are run-off lines for aircraft that have already landed but have either lost their brakes or simply can't stop in time. By following the line on the lakebed they will come to a complete stop. Obviously as Groom Lake is a test facility this is neccesary.

Fair enough i can understand such a theory, yet why (as in picture three, bottom left) would the runway actually build extra runway into the hook as such?? If an aircraft had lost brakes/ stopping time.. what would compensate for the extra added runway on that one particular stage?

I'm not quite sure what you are asking but I think you are saying "Why is there more runway runoff, if there is "the hook" for slowing down a speeding aircraft?"

If this is your question then I think you have a good point and I'm not sure what the answer is. Perhaps because using the hook is not always neccesary and just a run off id required in some situations.

I also have some additional information on the hook, it and the runoff on the runway were constructed in November 1960 for the A-12 programme. The runway was extended in October 1979. The runoff was also extended southwest in the mid-80s as the north end was prone to flooding.