the spurts of activity are when there is something to talk about.
At other times, there are fizzles of activity, when someone says "hello", and asks "how are things?". A few people will reply, but because most of the time, things are the same as last week, there is not always a lot of conversation momentum generated.
A few people have the ability to start and maintain a conversation, because they are dynamic individuals with a lot to say, that other people find interesting to reply to. This is the crucial thing - the interest of other people. Several people have a lot of things to say, but either the subject matter or the presentation, is not engaging enough for others to involve themselves.
Due to the glut of things to talk about with the Colelie incident, and the causes and effects of that, then a conversation, once started, gains momentum, and more and more people throw their opinions into the mix. Almost everyone has some interest in the matter, so everyone has reason to engage.