As someone who has never worked in Public Safety during a disaster, but has been through more than i can count on both hands, I probably have a very different take on all of this than most here.
Most people don't want to volunteer or help or anything like that. They want to be lookie-loos. Show up for a few hours, feel important, then disappear (similar to politicians). All they do is delay actual progress.
You want to be of help after a disaster? Great, thank you very much. STAY AWAY!!!
Still can't keep yourself away? Spend some time in your kitchen first, drop it off to the folks at the stations and camps, then GO HOME!
You absolutely can't bear the thought of sitting at home while people are suffering?
OK, fine, we can use you. Bring boots, gloves, a hardhat and a chainsaw if you've got one. Don't bring your radio, it's going to get broken. Haul limbs and junk to the curb for a few days. If you can do that, you might be the kind of person that we need to work in the disaster industry.
Centerpoint Energy notwithstanding, people in Houston have gotten to where they can return to a semblance of normality fairly quick. We're pros at carpet, drywall, and tree removal. When it floods, our Cajun buddies show up with boats and we get to high ground. It's almost a routine thing these days. If we need something, we'll let you know (and tell you who forgot to do it beforehand).
It's a great thing that people are still moved from our torpor and apathy to want to help in times of crisis. Compassion is and always will be a precious commodity. But Buddhist teachers will warn you about what they call "idiot compassion". Well-meaning, good-hearted folks are compelled to act, but ultimately make things worse.
Be moved. Let your heart break at the situation. Then think and look around. There's someone that needs your help right now, and you probably won't have to leave your own neighborhood.
And if you've never been in or seen the destruction of a large scale disaster, do yourself a favor and give it a pass.
Edit to add: no Public Safety experience, but 20 years in water utilities.