Did I hear something about a challenge?
Michael has challenged us all to present our project in our own words. I'm seeking to determine focal mechanisms for earthquakes to better understand why said earthquakes are being triggered. Based on this information I can then build by acoustic amplifier, find weak fault lines and wreak havoc across the globe before asserting my ransom demands. In the end it will boil down to world domination through means of seismology, huzzah! Or maybe I got it confused with a science fiction novel I read a while ago...oops. World domination sounded good though!
In case you haven't realized it by now, I have a very weird sense of humor and most of the above paragraph is shear nonsense (oh how wonderfully punny!). However, I am seeking to determine focal mechanisms for events occurring within a region of the Sierra Nevadas (between about 36.5->38 latitude, -119->-120.5 longitude) to ascertain whether they are truly doupl-couple events. The significance of a non double-couple earthquake is that it can be caused by events such as magmatic movement, which would support a theory that suggests that the root of the Sierra Nevadas is being peeled away. I think that about covers it, but I'm sure Andy will let me know if I missed something ;) Ah, one last note I suppose is that a large number of events within this particular event are deep crustal events, somewhere between 15 and nearly 50 km in depth. Again, the depth of these earthquakes is also believed to support the idea of a root that is being slowly "peeled" away.
Unfortunately the computer I'm working on currently in the lab hates the IRIS website and will kick me as soon as I log in. I'll attempt to find some work-around so that I can upload new maps and some signal analysis/polarity picks.
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Way to step up to the
Way to step up to the challenge! What is the relationship between magmatic movement (if they are non double-couple) and the root peeling away? What if the events are double-couple? How does that connect to the theory? Then to follow up with your final thought, why does the presence of deep earthquakes support the peel away theory?
As for those of you who like Jamie's first explainatin of world domination but aren't sure how to acheive it through tomography, you had better brush up on your Tectonic Weaponry
Shh, Michael, you'll give
Shh, Michael, you'll give the game away too soon. Tell you what, stop feeding the rest of the interns my plans and I'll give you a top position in the new world order
If the earthquakes are non-double couple and indicate magmatic movement then the thought is that the magmatic movement causing these quakes is likely the same process working on peeling away the root. The magma peeling away the root is effectively acting as a wedge, but to continue to act in that capacity there must be movement of magma into and out of this wedge, the movement that causes non-double couple events. If all the events are double-couple then perhaps there is a different mechanism for peeling away the root, or perhaps there's something completely different going on, but double-couple earthquakes are by far the most common so it'd likely be harder to use them to pinpoint a particular theory. The reason depth is an issue is that in this area the predominate events are shallow crustal quakes (say 10km or less), and in the area of interest for this study almost all the quakes recorded are greater than 15km, many of them up to 35 or 40km in depth. Based on some previous research done by Owen Hurd, a former student in this lab, the Moho depth in the study area is about 35-45km, indicating that these events are occurring fairly close to the crustal boundary. The significane of that is that there should be some kind of stressor to trigger events like this, especially seeing as ones at that depth are not as common in general but are prolific in the study area.
I hope that makes sense and clears some things up. I also hope that I'm pretty close to the mark on what I think is going on
We're not quite sure about
I'm inclined to agree with
See, if I gave you all the
That assumes we're the good
I like the first explanation
Yeah....So apparently my
I like the first explanation
I like the first explanation