I think any urban crisis is something to first avoid and secondly to get out immediately. I would equate to trying to hunker down in a forest fire…you’ll eventually get burned. If you don’t currently have a job and live in the immediate area, you’ll quickly become a refugee, target and eventually a victim. I won’t address the need for self-defense, I think most people concerned about a situation such as this know that self-defense is an essential…not all urban crisis bring people together in harmony…some of the worst animals on two feet quickly surface to take advantage of others. In fact, these are less than animals and I wouldn’t denigrate true wild beasts with the likes of these types of humans.
With that said, I think you need to be prepared to get out of the urban area immediately; and that means you have a plan, route, destination. Even if you have a vehicle, I would highly recommend a good mountain bike as a back up and better mode of transportation given the likelihood of heavy traffic jams and congested roads. You need to be as self sufficient and mobile as possible. If in an unknown city (visiting, business trip, etc.), make sure you have good detailed maps and even topographical maps (especially necessary in flood-prone areas).
I would have enough food and water for 72-96 hours…your goal (and plan) should be to get out. Outside of the typical mugger threat, cities are dangerous due to the high populations and close-density. Fires, earthquakes, pending blizzards or hurricanes, terrorist attacks (including bio/chemical), riots/gang eruptions, rapid viral outbreaks (okay…more zombie fears, but still potential for high-communicable diseases); all are potential hazards that you want to quickly evacuate from.
Here’s a older kit I had put together a few years ago:
Some considerations that I think are pretty important outside of a rural crisis…
A good ballistic eyewear to protect the eyes,
A good bicycle helmet to protect from falling debris,
A good pair of gloves to remove rubble and navigate through areas with jagged metal/broken glass
Wire/bolt cutter, hacksaw and pry bar
Smoke/dust mask
A small amount of climbing rope with anchor devices and appropriate training
Binoculars can be used effectively to avoid bad areas
A small emergency radio and even a portable police scanner could help to avoid bad areas
Maps and a compass are still critical
Good flashlights and extra batteries…I particularly like the hands-free headlamps
Cash is a great asset in an urban environment and a few hundred in small bills could make a big difference
The standard stuff still applies: appropriate clothing, first aid, water purification/method to carry, etc.
ETA: I to have the FUBAR and it would be a great tool for getting through some tough situations...
ROCK6