[PennyB]

Here is an interesting article on this region:

http://temblor.net/earthquake-insights/m...zone-1917/

[marc / berkeley]

Hi Penny!

I am still learning how to reply! (This is such a cool board with all new types of options...)

Thanks for posting this, it is really an eye opener!

With so many quakes in the region, I guess I lost the big picture (and one that Island Chris was trying to bring to light)!

The moment tensor if the recent December 8th M6.5 was spot on with all of the other forces in the region.  It  sort of relieves the stress somewhat along the diagonal faulting, but increases it along the Mendocino transform, likely increasing the likelihood of a large event taking place on or near the question mark, sooner rather than later.

Looking at the patterns, just for fun, to try maybe gain an inference.  There was a gap of inactivity between 2005 and 2014.  If one were to look at the faults, the Cascadia subduction zone and the Medocino fracture zone roughly look like a right angle.  The 2005 events form a rough line like a hypotenuse ( I suppose one could also throw in the 1984 event, but off topic).  Then a 19 yr. hiatus in the area of significant activity.  Then a smaller hypotenuse forms when activity resumes in 2014, and the 2016 event ( I suppose one could again throw in the 1995 event, but off topic).
It’s like successive waves of push forming stress and faulting, all pushing towards the convergence point of the Cascadia and Mendocino.

Could the question mark really be the approximate location of the next big one?  Could that event in turn contribute to some serious diagonal unzipping along the faulting once this big one occurs?

There is a pattern in play from the events on the map, if one minds the gap, and the pattern resumes, there will be a large event next year and another one 2/3 years after that.  If the gap represents a significant change, then all bets are off.

It’s going to be an interesting (and potentially scary) show!  There was a small normal component to the recent 12/08 event that was felt in Marin. So a lot of people might feel the next one!