My boss wants to have a system that takes into concern of continent wide catastrophic event. He wants to have two servers in US and two servers in Asia (1 login server and 1 worker server in each continent).

1. In the event that earthquake breaks the connection between the two continents, both should work alone. When the connection is revived, they should sync each other back to normal.
2. External cloud system not allowed as he has no confidence.
3. The system should take into account of scalability which means addition of new servers should be easy to configure.
4. The servers should be load balanced.
5. The connection between the servers should be very secure(encrypted and send through SSL although SSL takes care of encryption).
6. The system should let one and only one user log in with one account. (beware of latency between continent and two users sharing account may reach both login server at the same time)

Please help. I'm already at the end of my wit. Thank you in advance.