My whole HD is "Mac OS X Base System"
Probably your pMBR/GPT got corrupted or the Base System is somehow mapped falsely. Usually the first partition (EFI) and the last partition (Recovery HD) aren't visible.
Additionally a freshly erased disk0s2 ususally contains ~200 MB and not 1.4 GB (which is "by accident" the uncompressed size of a Base System).

The best thing is to completly erase the internal disk by whether:


Booting to Internet Recovery Mode by hitting altcmdR immediately after the start chime, repartitionung the internal HDD to one partition and installing a new system.


or


Attaching a thumb drive and installing a fresh system there. After rebooting from the thumb drive, repartition the internal HDD and install a fresh system to the internal disk.


In both cases the invisible EFI partition will be build automatically as well as the Recovery HD while installing a new system.