There are usually no interruptions during an application's migration process. When we migrate an application, the indices and settings are duplicated to the new hosting cluster from the old one before we delete anything, so your application remains available during this process.
Please note: when a migration is in progress, you should not update the name of the application - or any of its indices - until we confirm that the migration has completed
If you'd like to migrate an application from one region to another, you can contact our Support team for assistance.