Let me start by saying thank God no one was hurt. Second, do you have a full service maintenance contract with Otis? If so and devices (earthquake sensors) failed Otis should be responsible for the damage. Usually, a good elevator consultant can get Otis to move on this, they're less expensive than lawyers and get substantial results. Even if you get a lawyer (and few of them have elevator experience) he will immediately have to hire an elevator consultant or elevator expert to work on your behalf....
That said, look at iaec.org for a list of consultants in your area.
Good Luck