Earthquake

[Mike Petersen]

There was an earthquake at 6:40 AM Sunday morning. Fun!

[Linda Hegner]

Www.ds.iris.edu recorded mag 4.8

[A. Rodriguez]

Three small quakes near Paso Canoas, these are better magnitudes and locations than the global networks can give you.  The global networks also can not do the depth very well, these are all at about 25 km deep which places them on the subduction boundary, the Wadati–Benioff zone.  USGA probable can't detect the two after shocks,

hora Local: 6:38 am.

Localización: 3 km al Norte de Paso Canoas, Corredores.

Coordenadas: 8,567 y -82,842.

Profundidad: 23,8 km.

Magnitud: 5,5 Mw.

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Hora Local: 7:20 am.

Localización: 5 km al Este de Ciudad Neily, Corredores.

Coordenadas: 8,642 y -82,906.

Profundidad: 24,2 km.

Magnitud: 4,5 Mw.

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Hora Local: 7:27 am.

Localización: 12 km al Norte de Paso Canoas, Corredores.

Coordenadas: 8,651 y -82,816.

Profundidad: 28,5 km.

Magnitud: 3,6 Mw.

[Doug Johnson]

That's strikingly different from what other sites report, especially as to depth.

[Keith Woolford]

Doug, I've learned to wait for the ICG reports, usually not posted as promptly but with a higher degree of accuracy.

As Sr.Rodriguez points out, the Institute of GeoSciences at the University of Panama have sensors across the country and are better equipped to define these movements, imo. 

They are now reporting an another event in the same area but just across the border at 8:48 a.m.

http://www.panamaigc-up.com/ltimo-sismo-localizado-m-27-mw-31-01-20...

[Doug Johnson]

I'm still confused about the depth of the first quake this morning at 6:38.  Everything I'm seeing indicates that it was a shallow quake 8-10 km deep,  The subsequent shocks came from much deeper than that.

The only one I felt was the first quake.   I believe shallow quakes tend to be felt more widely than deeper ones of the same magnitude, although the first was significantly stronger than the others, of course.

[A. Rodriguez]

Hi

Yes shallow quake are felt stronger than deep quakes, it is all about distance.

Automatic locations tend to only use the vertical component and have real trouble with the depth.  When you see a depth of 10km what it mean is that the automatic system had no real idea of the depth and used the default depth, generally 10 km for a small event.

To get better depth a real person has to sit down and pick the S phases for several station and recompute, dropping stations that are outliers. 

I have attached a picture of the first event of this morning, notice that this picture only shows the automatic picks and locations the but it does use 115 stations and a depth of 6 km and it listed five calculated magnitude and chose M, I like Mw a bit better.  You can also see that the first location was archived in 51 seconds using 33 station

Magnitudes are all over the map most automatic systems will compute several magnitude non of them call Richter.  Most quoted are Ml for small events and Mw for events that are a bit stronger.

In the second image you can see that the network in CR is much better than the network in Panama and USGS has one station on Barro Colorado, they can only detect things above 4.6 Mw or so.

The solutions I posted were manually reviewed and the depths are very accurate because of shear number of station available.  Note that the second station on the list is BRU2 here in Volcan and it detected the event in 4.7 seconds.   

The USGS and other global networks can not detect small events and they are generally quite a bit slower because they need to wait many minutes for a good number of station to be involved in the solutions,  Costa Rica has hundreds of station in CR and the USGS has hundreds of station but on the whole planet. They also have some political reasons to be slow to publish their solutions.

[Doug Johnson]

Thanks for that great explanation.

[Pets Want Homes]

Several shocks as you noted.  The Sismos Panama put the bigger one at magnitude 5.

http://www.panamaigc-up.com/sismos/

[Jane Ritzenthaler]

Aftershock just now

[Gail Anstey]

The earthquake woke me.  Good thing because the power must have gone out and my alarm clock was flashing. I was fast asleep and I have to leave at 7:30 for the clinic.  LOL