Yeah, I wonder what the Monterey Bay Aquarium does. There's also a smaller aquarium in San Francisco. I don't remember what happened to that in the '89 quake there. I do know the building was damaged so they renovated it but no one said anything about the actual fish.
But consider, even if a betta tank survived an 8.0 quake, what about afterward? No power for the heater or filter, probably no clean water for changes. And I'm not sure, the shock of the quake itself could kill a little betta outright as they get sloshed around, possibly banging against the glass multiple times. It's a grim scenario.
They have those really strong Comman Hook brand velcro-type things for surfaces.. For smaller tanks, like 5 gallons and under, it'd probably at least keep it from lurching off the table, or fast enough to not catch it. They managed to keep my white board (large, with only 2 fasteners) on my door even when my drunk friend decided hanging off of it was a GREAT idea (sigh), with no damage to the door. They came off fairly easily, as well!
Growing up My father had 3 different 200+ gallon saltwater tanks, We lived about 15miles from the San Andreas Main Fault line. We had a number of 5.0+ earthquakes at that home. All the tanks were the same. The only real problem was the rolling blackouts in California during the late 90s and early 00s. Filter down for 24 hours is a bit uh-oh. The glass thick enough to hold the water within a little shake won't do much. Only falling debris will be a problem. Or if the tank is on a really weak stand. Think of how heavy, I mean 1gallon is roughly 8 pounds, so can an earthquake throw you off your bed in the middle of the night?