In the past, over 75% of submarine cable operators did not voluntarily
report outages of submarine cables with US landing points to the FCC. In
other words, less than 25% of submarine cable operators reported outages.
The FCC would learn about the submarine cable failures, sometimes days
later, from news reports or calls from the public.
Since the FCC treats outage reports as confidential information, that
still means the public will not necessarily be informed.
https://www.fcc.gov/document/fcc-adopts-rules-reliable-submarine-cable-infrastructure
The rules require submarine cable licensees to report major outages to the
agency’s Network Outage Reporting System (NORS). Other communications
providers – including wireline, wireless, and satellite – already report
outages to NORS.