The article about the 878 earth quakes states: ""This is the highest number of earthquakes at Yellowstone within a single week in the past five years," reported the USGS in a statement released last week."
So 5 years ago it had more earthquakes within a 1 week period but if I'm not mistaken it didn't blow up then either. Or maybe it did and I don't remember, or maybe it did and the guvmint hid the information from us.