If your storage account has GRS enabled, then your data is durable even in the case of a complete regional outage or a disaster in which the primary region isn't recoverable.
Note: The recovery time objective (RTO) is the targeted duration of time and a service level within which a business process must be restored after a disaster (or disruption) in order to avoid unacceptable consequences associated with a break in business continuity.
Reference:
https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy-grs
https://azure.microsoft.com/en-us/support/legal/sla/site-recovery/v1_0/