Still pretty decent, given the right circumstances.
For example, the 2011 earthquake in Japan resulted in damage to 7 cables[0]. But it wasn't the quake itself which instantly broke all 7 cables - they were destroyed by underwater avalanches triggered by the earthquake. Avalanches can occur hours after a seismic event, and some underwater avalanches go on for days.
I highly doubt that's the case here, but if you're asking about chances it's not as unlikely as you'd think!
For example, the 2011 earthquake in Japan resulted in damage to 7 cables[0]. But it wasn't the quake itself which instantly broke all 7 cables - they were destroyed by underwater avalanches triggered by the earthquake. Avalanches can occur hours after a seismic event, and some underwater avalanches go on for days.
I highly doubt that's the case here, but if you're asking about chances it's not as unlikely as you'd think!
[0]: https://www.theverge.com/c/24070570/internet-cables-undersea...