Around a 9.0, maybe a 9.1 or so.
Interestingly, the tsunami risk is related to the magnitude - but not always directly.
There was a large tsunami in the Pacific a couple decades ago, but the quake that caused it just wasn’t that big. Maybe a 7.0 or so.
But what happened was that something like 50,000 square miles of ocean floor just decided to fall - all at once - like 4 feet!
And in a few seconds, tens if not hundreds of cubic miles of ocean water was displaced.
Surf’s up!!!
LOL! You ever read a book called Lucifier's Hammer?? Sci-Fi book about a comet that hits the earth. Post apocalyptic. Great book. The comet calves just before impact and one of the pieces hits offshore of Los Angeles or someplace like that. A bunch of surfers are there and they catch the HUGE wave... like 400 feet tall. One by one they fall off their boards and of course die, but the best surfer in the group makes it like a mile inland or more and he feels like maybe he's going to live although he's still moving at about 150mph when he sees a giant skyscraper right in his path like a huge flyswatter....