Not at this pace.
Yes they happen at this pace. You just weren’t paying attention until recently.
And the question is what “pace” you are talking about; just ammonium nitrate explosions? There’s been two this year in the US. Or are you mentally adding in the Canadian fireworks explosion, etc.?
If you’re talking about all industrial explosions, then there are of course far more of those.
http://en.wikipedia.org/wiki/Ammonium_nitrate_disasters
There were 3 separate incidents in Spain, Romania, and North Korea just in just three months in 2004.
A random distribution of rare events will be naturally “clumpy” on its own, far more than the average person understands. If there are on average 1 ammonium nitrate explosion every year over a 50 year period, there’s not ACTUALLY going to be one a year. you’ll go three years without one, and other times you’ll have two explosions within three months, etc.
The only part that’s changed is the press covering it. Most of the time these things happen and nobody outside the local community finds out because it’s not news. But then slow news months happen and the press starts reporting these small events with bloodshed (if it bleeds it leads) to fill their time. We see it all the time. Remember all those shark attacks summer of 01? Seemed like the sharks had gone crazy, except that actually shark attack numbers were down dramatically from average, they were just getting covered on CNN which they usually don’t. Same thing with train derailments winter of 02. And train derailments again a couple months ago. The press has 24/7 to fill on three different networks, whether there’s something interesting happening or not, that’s what slush piles are for.