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Wednesday
Sep162015

West of Illapel, Chile, 16 Sep, 2015 - Mw 8.3

A large earthquake struck the coast of Chile tonight.  The map below is an update from around 11:00 UTC on 17 September. You can find many details at the USGS event page.

 

There are many openly available seismic stations in Chile, including a station very near the source region. Here is the channel list for the station at the Tololo Observatory in Vicuna, Chile. 

 For the mainshock, look at the accelerometer, which stays on scale for large events:

C;GO04; --;HNZ;TOLOLO OBSERVATORY, VICUNA, CHILE - Up-Down
C;GO04; --;HNN;TOLOLO OBSERVATORY, VICUNA, CHILE - North-South
C;GO04; --;HNE;TOLOLO OBSERVATORY, VICUNA, CHILE - East-West
Here are the records from the mainshock (you can see one of the early, large aftershocks in the "coda" of the mainshock signals and one or two others a few minutes later). The second image shows some of the large early aftershocks recorded on the accelerometer.






To watch later aftershocks, the broadband sensors should perform better, but for now, they are not behaving too well (perhaps driven off scale by many of the large aftershocks that occurred early).

C;GO04; --;BHZ;TOLOLO OBSERVATORY, VICUNA, CHILE - Up-Down
C;GO04; --;BHN;TOLOLO OBSERVATORY, VICUNA, CHILE - North-South
C;GO04; --;BHE;TOLOLO OBSERVATORY, VICUNA, CHILE - East-West