Earthwaves Earth Sciences Forum

Looks like there have been more M3+ quakes around Puerto Rico and the Virgin Islands the last 24 hours than what has been usual for the last weeks or months. Many of these are deep: 50 km in the north, 100 to 121 km in the south, which is the dip direction of the subduction zone.

We've been commenting here on swarms in this area, on Earthwaves, for at least a decade. The ones in the last 24 hours may be a bit different because they are really spread out over a large area (which has occurred before) and because they seems to define a S-deepening zone (don't know whether this was the case on any of the earlier ones we noticed). I don't think any of the other swarms in the last decade led to a major quake.

Chris

(01-16-2017, 08:55 PM)Island Chris Wrote: [ -> ]Looks like there have been more M3+ quakes around Puerto Rico and the Virgin Islands the last 24 hours than what has been usual for the last weeks or months. Many of these are deep: 50 km in the north, 100 to 121 km in the south, which is the dip direction of the subduction zone.

We've been commenting here on swarms in this area, on Earthwaves, for at least a decade. The ones in the last 24 hours may be a bit different because they are really spread out over a large area (which has occurred before) and because they seems to define a S-deepening zone (don't know whether this was the case on any of the earlier ones we noticed). I don't think any of the other swarms in the last decade led to a major quake.

Chris

I seem to recall that when the activity started we all were wondering when the big one would hit. And as you pointed out we're a good decade later and still nothing. Just goes to show how little we all know about the dynamics going on deep inside the Earth.

Something obviously changed down there. The 'norm' is different than it used to be. Like Oklahoma.

Brian

Brian,

If the quakes are on or close to the megathrust of the subduction zone, and having that many 3+ in 1 or 2 days is not a coincidence, then one might speculate that there is some sort of slow slip event, like they see in Cascadia. Except likely different because I don't think Cascadia slow slip events are associated with that many M3+ quakes.

qualifier: I don't 100% know what I am talking about in this post: it is hypothetical to speculative.
Chris