Each area has a "region" or zone. Dependent upon the degree of disaster and location if you are deployed. The problem I have seen others have is the deployment issue. Minimum of two weeks immediately, bosses do not always like that. As well, that is a minimum sometimes.. as well, most of it is not emergency care but routine medical care, such as tetanus shots, cleaning wounds, bandaging, even setting up portable potties (public health) etc..
The pay will usually compensate you enough, but I have always spent more (food, water, etc). No one usually gets rich, usually a little in the hole. Remember, you are usually under the orders of a physician and accompanied by nurses, RT's, pharmacist, etc..
R/r 911