It would though.

You could evacuate areas ahead of time if a large enough earthquake is predicted, or get humanitarian aid set up ahead of time. Imagine if food or water was already there in the moments after an earthquake instead of a day or two later. We could pre-set up halls and other places as emergency accommodation before the earthquake even hit, and tell people where they are ahead of time before communications could be damaged.

People would know it's a bad idea to go swimming or climbing during those days. It would also be a great opportunity for people to get their earthquake plans sorted, pack things they want to bring with them if they get evacuated.

It's easy to put off planning for an emergency when it's a hypothetical but if you know there's a 90% chance it'll happen in the next few days it's a lot easier to get motivated. Obviously people will still procrastinate but it would help.

Of course inaccuracy could be a huge issue, especially with people not trusting it. But it would be a great boon if it worked well.