Right now the problem actually seems to be logistics. You can use the Marines as first responders -- what you need are helicopters and landing craft, fuel, power, comms, food, and water, which are exactly what a combat force uses in an assault as well. By downloading weapons, they could take extra supplies for civilians, and their own support.
The deterrence point of doing it instantly is that you can show just how fast and how hard an amphibious force can deploy. That's pretty much the only value of an amphibious force like the doctrinal mission of the Marines anymore; they'll never do an opposed amphibious landing with a long lead up, due to ATGMs/etc. being so effective.
One of the best things the US Military has ever done for our national security in the war on terror was helping out pretty substantially after the Kashmir 2005 earthquake -- there were helicopters in the air hours after it hit, from the US and UK forces in Afghanistan.