97 Years Since the Eruption of Lassen Peak

Considering all the time I spend thinking about Lassen Peak and its related volcanic siblings (like Chaos Crags or Bumpass Mt.), I thought I should at least acknowledge the 97th anniversary of the eruption of the volcano. You can read all about the eruption on this USGS/NPS site or check out the USGS fact sheet (pdf) on the eruption, but it stands out as the most recent Cascade Range eruption that didn't happen at St. Helens. When you think about it, that is a long time for a volcanic arc like the Cascades to lack any eruption other than at a single volcano (St. Helens) - almost 100 years. If you look back at the historical record, which is somewhat scant and slightly questionable, it seems that the Cascades were much more active during the 1700's and 1800's, but very quiet since then. This is an open question in volcanology - why have they been so quiet? This might be just an example of "small sample size" issues in thinking about geologic processes, but it is interesting to ponder.