Other than doing a Google search on each one of these “styles”, i.e., “Ibiza trance, classic Detroit techno, classic Chicago house, Cologne minimal house and Berlin dub techno, Rotterdam gabber hardcore, Madrid industrial and Frankfurt noisecore”, is there a single source that might explain them. I don’t live or move in those circles and haven’t a clue as to what they are or mean. I did see a German video showing aerial shots of the Duisberg debacle and it looked decidedly decadent.
Interestingly, I would say that there isn't a good online site because (1) the scene is so "in the know" that there is no real site for beginners that's reliable and (2) even Wikipedia is not overly helpful because there are so many wars in the editing over what belongs where.
The Rough Guide series had a good book about it, but it's out of print and out of date.
Suffice it to say that electronic music is very dependent on dance clubs and the DJs that perform sets in those clubs. Scenes coalesce around specific clubs in specific cities where certain varieties of the music become very popular.
The main centers of electronic music today are NYC, London, Berlin, Cologne, Rotterdam, Frankfurt and Barcelona.
But plenty of cities used to have very vibrant scenes: Chicago, Detroit, Bristol, Madrid, Paris, Ibiza (a Spanish resort area) and others have smaller scenes.
One major variety is trance - dreamy, blissed out and undulating (particulary popular in Spain, France and Italy - also know as chillout or lounge techno).
Then there are the various varieties that end in "core" that are characterized by fast, pounding 4 on the floor beats, up to 220 beats per minute (very popular in Holland and parts of Germany and parts of the UK).
Then there are the reggae/dancehall influenced genres that are characterized by "broken" non 4/4 rhythms like trip hop, drum'n'bass, jungle, garage, 2-step, grime, UK funky and dubstep (all very popular in the UK).
Also there are the minimal styles like minimal house, ambient, glitch, "clicks and cuts" and dub techno that are generally mid-range 4/4 characterized by clean production and precise and spacious sounds (very popular in Germany).
There are a hundred other styles, some of which are defunct but considered classic, and others which branch out into more organic, non-electronic styles like acid jazz, neofunk, afrobeat revival, etc.
I did see a German video showing aerial shots of the Duisberg debacle and it looked decidedly decadent.
The bulk of the parade is essentially a decadent gathering in the sense of an American spring break - a lot of drunk young women in bikinis.
The counterparade is decadent in the sense of a Gay Pride Parade afterparty in San Francisco and we'll leave it at that.