A matter of language to consider: the difference between an emergency and a disaster. IMHO, these words are not interchangeable.

So, what's the difference?
An emergency is an event that must be addressed quickly to avoid more serious consequences.
Examples:
a gas leak, broken power lines on the ground, a heart attack, a localized fire, a nasty road accident, etc.

A disaster is a catastrophic event that exceeds the ability of the community to cope.
"Community" can be small, as a household; or large like a region or a country.
The important distinction is that responding to a disaster requires help from OUTSIDE the affected area.
Examples:
The lava flow in Hawaii is a disaster ONLY if Hawaii can't handle the situation on its own.
Hurricanes, like Andrew, Katrina, and Sandy, created disasters because victims in the affected areas required outside help.

A point to keep in mind is that, in a disaster, local responders (including hams), may be as affected by the disaster as everyone else in their community and, therefore, will not be able to respond.

This distinction, needing help from outside, gives hams a huge advantage in disasters -- we're used to working with each other taking advantage of common frequency plans and on-air protocols, no matter where we're from.

- Art Feller, W4ART,
Communications Specialist (retired),
Office of US Foreign Disaster Assistance (OFDA),
Agency for International Development (AID),
Department of State

SOURCE: www.arrl.org/ares-el?issue=2014-12-17