GCP has multiple zones in the same physical building. Not all cloud providers have distinct physical buildings for each Availability Zone.

Do they have an official description what a zone is somewhere?

Back in the days when we had our own data centers a zone was defined as a "fire section" meaning that it should not be impacted if any other zone of the data center had a fire. This obviously means that you can't call 3 floors of a building a zone.

Edit: The information on this site https://cloud.google.com/docs/geography-and-regions#regions_... clearly states that a zone is "physically distinct" so they have some explaining to do.

Edit 2: Sneaky... They changed the status page to say "europe-west9" instead of "europe-west9-a".

I could not find the GCP equivalent to this from AWS:

"AZs are physically separated by a meaningful distance, many kilometers, from any other AZ, although all are within 100 km (60 miles) of each other."

https://aws.amazon.com/about-aws/global-infrastructure/regio...

Physically distinct could refer to distinct hardware in the same building and cage space. It’s “physically distinct”. Google makes no promises that the zones are in different buildings or separated by N feet/miles of space.

AFIK all zones (a, b, and c) have been reported to be down. I'd love to understand ehat happened.

A cooling pipe started leaking and set the batteries on fire.

Probably some dependencies they did not plan for

Switching off all of 1 zone and checking the others aren't impacted is literally step 1 of checking your organisation is truly zonally redundant...

Someone as big as Google ought to have been practicing this automatically every week in a staging environment, and probably at least annually in production.