Tuesday, February 12, 2013

Collecting some links on the North Korean nuclear test

Valuable information about North Korea's nuclear test comes from seismological recordings of the shock waves produced in the event.

One of the interesting things is that because the North Korean nuclear tests are basically done in the same place, seismograms of the events at long distances have quite similar characteristics. Their amplitudes, however, do vary with the increasing yield of the events.

Here are a few links I have come across:

How do we know it was an explosion and not an earthquake? First of all, that part of North Korea is not known for historic earthquakes. Secondly and more to the point, with seismometers arrayed around the source area regionally and globally, the explosion will cause all of the first motions to be AWAY from the source. If it is an earthquake, two quadrants will be pulled IN towards the source and two quadrants will be pulled out ("double couple").

--disclaimer: this is not my area of expertise, but I do find it fascinating. To some degree, monitoring of nuclear tests using seismology has driven the development of seismology and seismic networks and that lets us learn a lot more about earthquakes globally.

Thursday, February 7, 2013

Paleoanthropology research in the Afar, Ethiopia

I just got back from some fun field work in the Afar, Ethiopia. Here are some pictures. Our project there is called the Ledi-Geraru Research project. The research is done in collaboration with Kaye Reed and Chris Campisano from the Institute of Human Origins / School of Human Evolution and Social Change as well as with Ph.D. students Erin DiMaggio and Dominique Garello. Erin is just finishing up a substantial Ph.D. effort on the geology, stratigraphy, and tephrachronology of rare Pliocene units (about 2.9-2.7 Ma) that critically span a time gap otherwise mostly missing in the region. Dominique will be working with Chris Campisano and I on the geology of the Ledi-Geraru, as well as this drilling project.

Here are a few other posts on this topic:
We started this project with Charlie Lockwood and miss the chance to share its successes with him.
Here is an old page with maps
Here are many pictures from over the years:
Ethiopia and Afar region (2002)
Ethiopia and Afar region (2004)
Ethiopia and Afar region (2005)
Ethiopia and Afar region (2006)
Ethiopia and Afar region (May 2008)
Web-sized images for Ethiopia and Afar region (November 2008); Ethiopia and Afar region (November 2008) full size images
Web-sized images for Hadar Field School (2009); Hadar Field School full size images
Afar region 2012
Afar region 2013