Kettling or corralling usually is a tactic used by law enforcement to prevent riots. It often is predictable where and when it will be done. Around here it´ll be rallies for very controversial topics, certain soccer games (if you see police in riot gear in Dresden, stay clear of the main train station and the way to the arena) and the traditional 1st of May events.
The rules for not getting caught in a riot apply here as well. Best strategy is to not be there when it happens.
The good news is that news channels often announce those events. The phrase "the police prepares for [insert event of your choice]" is a give away.

If you are not following the feeds of the people organizing the unrest, it may come as a surprise and you may not have the opportunity to depart. Avoidance would be best, but if you can't avoid, stay low and do not attract attention. Do not be an inviting target of opportunity. Crowds do not behave like rational and logical people. Yes there is almost always someone instigating or even directing, but the majority of the people are like cattle, angry and violent cows. They will follow the leaders. Especially when they believe they will remain anonymous. Anonymity changes the way people behave. A large crowd provides anonymity by itself, but when they are hiding their faces be ready for violence. Know what your priorities are for security (family, self, property), and find an escape route if you are targeted. The first thing a sniper does before he establishes a shooting position is to plan his escape route. If you are hunkering down, know how to get out and away from the threat.

Whilst times are normal, I believe in not attracting undue attention.
Dress in a similar style to those around you, don't stand out.
Avoid expressing strong opinions on politics, morals, religion, or even sporting teams.
Democracy is important, but I limit my involvement to voting for the party that I support. And maybe attending small, local, indoor meetings, I would never attend or go near any large scale political rally.

In times of tension or impending riot, stay away from trouble, possibly stay indoors.
Keep an eye on the news for events that could lead to disorder.

Cary a concealed weapon where lawful, but remember that it is better to be in some other place rather than getting into a shoot out.

Make your home as secure as possible without looking like a fortress or being in any way unusual.

Keep supplies of food and water, for emergencies in general and in particular to avoid any need to go the shops for a few days.

That goes with what I was saying about being the grey man.


Jeanette Isabelle

Mr. Grey can always get caught up in the stampede when he/she is in the wrong place; being grey only takes you so far. How do you dress grey at a political rally, not wear a red hat? Yeah, that’ll work - not. In the vicinity of a riot the only person who’s grey is the one who isn’t there.

I don’t even watch these rallies on the news, I have no interest.

You can do everything perfectly, and it can still go wrong on you. Be prepared for it.

I should have bought that "Deplorable Me" T-shirt?

Jeanette Isabelle

I sense a mixed message in that post (possibly due my reading), particularly the comment about carrying a concealed weapon. Don’t carry because of the riot, but rather because you always legally carry a concealed weapon. IMO, people who carry a firearm into a riot are either LE, wannabe LE or bad guys. That said, at least for me, carrying forced me into a heightened state of situational awareness. In many cases (again my opinion), that situational awareness is much more useful than the firearm for personal defense if you heed the signals and leave. I’m not a member of LE so I’d much rather avoid, step well away and be prepared with my cell-phone and camera from a safe distance. $.02

good intelligence is your friend...as a former analyst of military radio communications I worked with the world's best Morse operators and foreign language specialists... unfortunately I don't have that resource today....as commented the social media sources are available, but I would rather go to the action arm of the local law enforcement, or fire rescue... even with encrypted or duplex (transmit on one frequency and receive on another) a few nights of playing with a frequency scanner can produce some clues, even if you are not able to actually understand the conversations

a change in the amount of radio traffic on a certain frequency is a clue... if you can associate actual incidents reported in a paper or on TV to previously observed increase of radio traffic, it may allow you to identify particular geographic areas covered by that frequency

a "broadcast" transmission without any response from other units typically reflects a high command authority... usually on a higher frequency

in the clear air to ground communications between air units and control

increase in local amateur radio communications... CERT communications

an area I am negligent in is not having a small portable AM/FM pocket radio with ear bud when away from the car, though I don't really spend time in large urban areas

don't forget the OODA loop

Observe....
Orient...
Decide....
Act...

a neutral color baseball cap, sunglasses, and if not out of place a hoodie helps you remain grey...

The law enforcement and emergency services would give you information once something begins, but these protest groups use text and social media to plan, recruit and coordinate. I am not sure HAM or other radio transmissions will give you advance warning.