I'm just being pedantic here, but at 76,207 persons per square km (UNRWA), Jabalia is nowhere near the most densely populated urban area on earth.
Having been to several Gaza refugee camps, and having lived in downtown Cairo, the latter is much more densely populated (around 136,000/km2).
Parts of New York are over 110,000 /km2, and parts of Mumbai over 150,000 /km2. Parts of Hong Kong city (not territory) are 1,924,263 /km2, or 26 times more dense than Jabalia. You'll find some comparative statistics here.
This isn't to say that Gaza isn't very crowded—it is. It also has a very young population (63% are aged 19 or younger, and 39% are under aged 10 according to the 1997 census). As a result, military operations there are akin to a shoot-out in a primary school—with all the inevitable resulting human tragedy.
Bookmarks