Using this you should be able to manually trigger a failover to another Azure region but there will be no automatic failover of VPN connection. You will have to manually build a VPN connection to your on premise and the new VNet and have that as a standby in the event of a Azure datacenter failure.

https://www.social.msdn.microsoft.com/Forums/office/en-US/b46f540b-ddac-426c-9bd1-2ed2d8cd7c90/onpremise-to-azure-vpn-tunnel-automatic-failover?forum=WAVirtualMachinesVirtualNetwork