School shootings: malignant, contagious social meme?

I've been trading emails with Loren Coleman lately about the rash of school shootings in recent weeks. On September 14, Canadian Kimveer Gill attacked. He was said to have had a fondness for the Columbine shooters (he certainly loved the game). A number of similarly of deadly incidents followed, right up to today's death spree at an Amish school in Pennsylvania. Seems like a lot in a short period of time. Coincidence, or social phenomenon?

Coleman is a suicide prevention and school violence
researcher and consultant, and author of Suicide Cluster (1987) and The Copycat
(2004). He writes:

Here is what I am finding:

* Most contemporary school shootings tend
to occur primarily during two periods of the
school year – at the beginning (late Aug
through October) and near the the end of the
academic year (March-April).

* Copycats follow a regular temporal
pattern that repeats – these could be after
a primary media event in a day, a week, two
weeks, a month, a year, ten years –
vulnerable humans have internal media

* Copycats imitate the previous violent
attacks, oftentimes down to specific details
as that mirror the previous specifics of the
shooter, the victims, and the methods.

* "Celebrity" events have a far-reaching
impact and modeling effect — so, of course,
Columbine serves as a dark cloud over many
school shootings.

One of the silliest things I have heard from
cable news in the last several days during
mid-September 2006, is that "these school
shootings aren't like the other school
shootings." This is short-sighted, and factually

Before the current model (post-1996) in which a
member of the student body would go into their
own school and kill fellow students, the pattern
was one of outsiders — often adults — going into
schools and killing students. In my book, I
discuss some of the more infamous cases (…).
Every year is different, and a fresh view must
be considered based upon observations that are
right in front of our eyes. What I do at the
beginning of a new school year is to see if
there is an emerging pattern that will be the
re-worked "copycat" model for the new school
year. To me, it was and is obvious where we were
going this year.

Here's what I see: a mix of outsiders invading
school, and students making plans too (…)

Link to the website for Coleman's "Copycat Effect" book, with the full text of this essay. Here's a related post on his blog, in which he predicts more shootings in October as the social contagion spreads during this present cycle. Here's a related news item: "Six school shootings in less than six weeks: experts comment on cluster," in Canadian Press.