"Well, it looks like 700-900 year intervals, so we're about 500 years overdue, assuming it or they have some sort of regular periodicity." Just something else to worry about along with West Nile Virus, SARS and Mousepox. LOL.
BTY, Mike Baillie, in his book Exodus To Arthur touches on the (apparent) 700 year cycle. Don't forget we had the 1908 Tunguska explosion (impact).
You're correct, of course, about the Siberian thingy. But I'm not going to get complacent and assume that we're good until 2800 AD - I'm still taking my ballglove out with me...BTT...