DISCUSSION 6: Linking deformation between the surface, crust, and mantle
Paper1: Subcontinental-scale crustal velocity changes along the Pacific-North America
plate boundary. Davis et al., Nature (2006).
Summary:
Using continues GPS data to talk about the sharp boundary. Stain started from east
transfer to west over 1nm/yr.
Brainstorming:
• In Fig2, it will be better to plot the derivative of the derivative so that we can see the
slope changing. Plotting a year of the slope change might be able to see more clear
velocity changes. Matt mentioned actually Davis has upda ted figure to show the
eastward and westward spatial and temporal motion.
• Why do they use 2.5 years? Does the value 2.5 come from some portion of time? Why
do they use the earliest 2.5 years not latest 2.5 years to determine the trend? When
they choose another reference, the eastward motion might be westward motion and
westward motion might the larger westward motion.
• GPS should care lateral and vertical motion. In the paper, they showed lateral variation
only. It might not have a lot of vertical motion. Also, the vertical motion is also
difficult to measure.
Paper2: Absolute plate motions constrained by shear wave splitting orientations with
implications for hot spot motions and mantle flow. Kreemer, Journal of Geophysical
Research (2009).
Summary:
In Fig3, it shows simple cases to explain the observed difference in hot spot velocity and
absolutely plate motion velocity.
Brainstorming:
• You have something on surface. You can dream of the story happen beneath it.
• Is the flow of the motion a control factor or not? Is it driven by convection model? A
Chickens and eggs problem.
Paper3: Rotation and place locking at the southern Cascadia subduction zone. McCaffrey
et al., Geophysical Research Letters (2000).
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