Jan 31, 2015 Panama fracture zone shakes it up

There was another earthquake along the Panama fracture zone today, following a couple from earlier in the month. Today, there was a Mb 5.1, while on 1.16/2015 there was a Mw 6.6. There was a swarm along strike with the PFZ in May of 2014.

Here is a global scale map.

This is a more regional/local scaled map with some interpretations on it. The moment tensor for the Mw 6.6 earthquake is plotted.

Here is Abratis and Wörner (2001) figure, showing their interpretation of the regional tectonics.

Here is Coates et al. (2004) version.

This map, from Morell et al. (2013) shows the age of the oceanic crust, drawn in lines that are sub-parallel to the magnetic anomalies in the oceanic crust.

Here is a USGS graphic showing how these magnetic anomalies are recorded and then measured in the oceanic crust.

This map shows the earthquakes from May of 2014.

This map from Morell et al. (2013) shows the extension of the PFZ beneath Panama, which is probably what was responsible for the earthquakes in May.

Also, here is a short explanation (from the USGS) of the graphical solutions for focal mechanisms. While moment tensors (shown in my interpretation figure above) and focal mechanisms are determined differently, their graphic representation of the deformation from earthquakes is the same.

References

  • Abratis, M. and Wörner, G., 2001. Ridge collision, slab-window formation, and the flux of Pacific asthenosphere into the Caribbean realm, Geology, v. 29, no. 2, p. 127-130.
  • Coates, A.G., Vollins,L.S., Aubry, M-P., and Berggren, W.A., 2004. The Geology ofthe Darien, Panama, and the late Miocene-Pliocene collision ofthe Panama arc with northwestern South America, GSA Bulletin, v. 116, no. 11/12, p. 1,327-1,344.
  • Morell, K.D., Gardner, T.W., Fisher, D.M., Idleman, B., and Zellner, H., 2013. Active thrusting, landscape evolution, and late Pleistocene sector collapse of Baru Volcano above the Cocos-Nazca slab tear, southern Central America, GSA Bulletin, v. 125, no. 7/8, p. 1,301-1,318.
Category(s): Chemeketa Community College, earthquake, education, geology, plate tectonics, subduction

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