The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States.

According to many scientists, the next rupture of the Cascadia Subduction Zone will spell the worst natural disaster in the history of North America…

So those interested in tremor and seismic swarms will have noticed an episode under North Vancouver Island that has been progressing for 9 days.

Total seismic activity from 12/28-01/06.

Activity has been very moderate. It has exhibited an interesting pattern, tending, for whatever reason(s), to seem to be segregated by the Nootka Transform Fault that separates the Explorer Plate to the NW from the Juan de Fuca Plate.

I’ve posted below screen shots of the activity by day for you to see the evolution of the swarm…

And here the overall situation again…

Total seismic activity from 12/28-01/06.

This kind of tectonic tremor occurs at multiple subduction zones on the planet. ‘A’ theory is that it’s related to fluid movements in porous rocks at the subducting plate interface with the overlying crust. If it means more than that scientists haven’t found data to substantiate/prove that/those conclusion(s).

Or maybe the Cascadia is about to blow and trigger the largest disaster in North American history… [PNSN, Nature]

(Source)