Google Cloud Platform: Physical snapshot storage location

This document says:

Compute Engine stores multiple copies of each snapshot redundantly across multiple locations with automatic checksums to ensure the integrity of your data.

I'm wondering about the multiple locations part and can't seem to find a definite answer. What exactly does that mean? When I do a snapshot of a disk in us-east1, is the physical data distributed to other geographic locations, and if yes, where to exactly?

Snapshots are a global resource, as specified here:

Global resources are accessible by any resource in any zone within the same project. When you create a global resource, you do not need to provide a scope specification

This means that Google manages the storage and redundancy of the resource across global resources without exposing the details to the customer.