Every time we in the D.C. area have an unusual event, such as the Aug. 23 earthquake , it’s characterized as “ a wake-up call. ” Any hotel guest knows that a wake-up call is only worthwhile if the sleeper actually wakes. It’s time we woke up to the need to clarify who in this city can order it evacuated.

We’ve had a lot of potential evacuation scenarios over the years — what if Hurricane Irene had required a mandatory evacuation? We had one terrorist attack on 9/11, what if there were another? What if there were a hazardous material spill? Every time there’s an emergency, the results are the same: snarled traffic, dead cellphones and packed Metro cars.

But aside from the technical aspects of getting everyone out of the city — a daunting task — of equal importance is the question of who has the authority to order an evacuation. In nearly all cities the answer is simple: As Michael Bloomberg showed as Irene approached, it’s the mayor.

Because of the District’s unique status, however, that ultimate authority is not at all clear, given the significant limitations of home rule. I was particularly struck by this at a May 2006 panel at Georgetown University, when I asked the commander of the U.S. National Guard Bureau, the sitting and former commanders of the U.S. Northern Command, and former Virginia governor James Gilmore who had this authority. None of them knew.

It is past due for there to be clear, transparent lines of authority for ordering an evacuation of Washington should the need arise. As best as I can determine, such lines of authority are currently lacking, or if they exist they are not apparent to the public. They should be.

Most people might think that the president or the mayor could order an evacuation. However, since Washington is ultimately a congressional city, it would seem that the final say should rest with the top congressional officer: the speaker of the House.

If it is the speaker’s call, it would also be smart to have him delegate the authority for an evacuation to the appropriate official, most obviously the mayor.

An emergency is not the time to have officials wrangling over who is in charge. That happened during Hurricane Katrina in 2005 in New Orleans, and lives were likely lost because of it.

A municipal evacuation is an extraordinary and complex event. One hopes that it will never happen here. But should it ever be necessary, it will be critical that the authority for the order be clear, obvious and legitimate.

We’ve had our wake-up call. It’s time to get out of bed.

David Silverberg is editor of Homeland Security Today magazine.