Hi Barry, welcone to earthwaves if you have not posted before. Good question and good observation; I had missed that.

Before I comment, we have not posted on that earthquake, so I put the link. A couple of days ago there was M7.1 thrust earthquake (either very steep W-dipping reverse, or rather flat E-dipping thrust). The depth is about 35 km. It is 219 km south of Santiago (but that is the epicenter; if it ruptured north it would radiate energy closer to Santiago).

OK, the USGS list that is linked only gives global M4.5 and above or "significant" quakes. They might give a M3.5 if it were in London, but I think we can assume there could have been aftershocks smaller than 4.5 that are not listed. Were you checking the USGS list or another one? It would be interesting to know if there are aftershocks smaller than 4.5 and bigger than 3.

But, yes, one might expect a 7.1 to have aftershocks larger than 4.4. There have been posts here about few aftershocks on other quakes. A month or 3 ago there was a quake beneath land near the coast of Northern California. I forget the magnitude, and I'm too lazy to check, but I recall it was just less than M6. There were posts here about the lack of aftershocks. Also from (failing) memory, that quake was at a similar depth to this one, but was "normal" (stretching) rather than thrust, and was within the subducting slab.

The Chile quake was of a dip and mechanism that it could have been on the megathrust between plates rather than within the slab.

Heartland Daughter (HD) lived in an apartment in Santiago for 6 months starting June 2010, after the Feb 2010 Chile M8.8. I guess her Chilean host mother took a real pounding in that quake, and was scared when there was a M6.5 aftershock while HD was there that made the table dance. That aftershock was farther away than this one. I think the table must have danced.

Chris

• Chile M7.1