Do blog posts (their frequency) follow a power-law distribution? Why?

Writing is known to be a streamlined channel for peoples' thoughts; blogging (micro-blogging too, of late) provides a platform where people can share their thoughts with the general public.

Time and again, the pattern shows up. The pattern where people blog very often for a short duration of time, and hibernate for a relatively long time. I feel the time-between-two-posts follows a power-law distribution. It would be nicer if one could validate the same; the knowledge would definitely help blog service providers in efficiently using their resources.

However, my interest lies in understanding why people go through these cycles of activity and no-activity. Is it because people have their own reasons to blog, and those reasons surface only from time-to-time. If that is the case, wouldn't it be amazing to conduct a survey on why people blog in the first place? Do people even know their prime motivation for blogging? I definitely don't. This reminds me of a conversation with a friend who studies communication. 

Apparently, in communication classes, the students are taught that each blog is supposed to have a theme/purpose. Though the merit of such an argument is questionable, how many of us actually set out with a purpose in mind?