Fall, 2013
Instructor: Andrew Newman

Geodynamics: Home

From 08/21/2013
  • NY-Times article on Plate Tectonic Forecasts (pdf version)
  • Peter Bird's Geochemistry Geophysics Geosystems, 2003 paper (password protected)


    (pdf version)
  • China's Plate Interior Seismicity

    click on above image for PDF version of the East Asian Seismicity map. Note that seismicity occurs well away from the plate boundaries (Himalayan front in northern India, and Philippine subduction in the east).

  • China's Internal Deformation

    Recent Map of China showing present-Day crustal deformation rates constrained by Global Positioning System (GPS) Measurements, (Liu et al. GSA Special Paper 425, 209-318, 2007. )
  • Changes in Sea level over the past 600 Ma
  • Reconstruction of the Plate configurations during the late Cretaceous (80 Ma)

    source

From 8/26/13

  • Seismicity surrounding the Juan de Fuca Plate identifies the Juan de Fuca Ridge, Mendacino Fracture Zone & Triple Junction, Explorer Ridge and sub-plate, and Cascadia Trench. [Mouseover] The Juan de Fuca collides into North America at 3-5 cm/yr buidling significant strain energy for release in future earthquakes.

  • Cocos Plate (Euler Rotation Visualized)

    From this image, the relative plate motions are obvious, and because the absolute pole of Cocos plate rotation is near, the transform faults and ocean ridges for clear small and great circles identifying the pole.



  • Plate Kinematics Handout (from Stein and Wysession p. 290-296; password protected)
  • GeoMappApp a physiographic earth viewer

From 9/9/13


  • From 09/18/13
    • SRL

      More information on NASA's use of Satellite Laser Ranging (SLR) to track the Lunar Reconnaissance ORbiter (LRO) can be found here.

    • VLBI

      Solutions for plate motion across: the western US, East Asiaand Japan.

    • GPS-derived Plate motions (REVEL)

      Similar to the geologically-derived (NUVEL1a), but with data collected over motions from just 10-15 years, rather than over 1 Ma. Interestingly, away from active plate boundaries, results are consistent at about 97%.

    • Complex motions of Microplates show details of Euler and continental motions



    • Current Global GPS velocities
    • North American Plate Motion
      (from Calais et al., 2006)
    • After removing Euler motion, left with residual motion (mostly isostatic rebound)
      (from Sella_et al.,_2007)

      GPS and InSAR processing
    • My pages describing GPS data reduction using Gipsy.
    • My pages describing InSAR processing using ROI_PAC.

    • InSAR image or deformation due to the Hector Mine Earthquake in October of 1999.

    • Western US InSAR Consortium page

    • LIDAR Imaging during recent activity at Mount St. Helens in Sept and November 2004

      from USGS

  • From 11/04/13

    • While thermal cooling models suggest plate rate is highly dependent on the age of plates that are subducting, it is found that the percentace of plate edge that is converging is a much better indicator of rate. It may be beneficial to think of why?(from Stein and Wysession)

    From 11/11/13
    • Mohr's Cirle Diagrams for stresses on arbitrary planes/faults.
    • Time dependence of stress and fault slip.
    • Byerlee's Law [PAGEOPH 1978]:

      Identifies the emperical relationship between the shear stress required for slip under a range of rock types and normal stresses (Figure from Stein and Wysession).
      • Under 200 MPa of confining pressure, material appears cohesionless with a coefficient of friction near .85.
      • Over 200 MPa, material appears cohesive (50 MPa strengh), but with a reduced frictional coefficient of 0.6.

    From 11/13/13
    Debris Flows:
    • The following two lectures will primarily come from Iverson, Rev. Geophys. 1997 .
    • and Iverson, "The Debris-Flow Rheology Myth" in Debris-flow Hazards Mitigation: Mechanics, Prediciton, and Assessment, 2003 .

    • Illustration of of 120 km long, 1 cubic-km Osceola debris flow from Mt. Rainier which formed about 5600 years ago, possibly due to a magmatic intrusion event. Much of eastern Tacoma is now built on this relatively flat and well drained deposit. More information, and the source of this figure can be found at the USGS
      .
    • Longitudinal Profile of the West Fork White River path:

      Profiles are shown along path route, first 1:1 scale than ~10:1. The mapview shows the digitized path (faint white dotted line).
    • Video footage of debris flows:
      • Section of unconstrained flow with heavy deposition:

        Note:
        • Repeating surge heads: controlled by granular friction.
      • Very wet debris flow in N. Afganistan caused by large rains and snowmelt:
        Note:
        • Surge head: mostly rocky but with some preceding fluids (low pore-pressure).
        • Transport of large cobbles throughout, and some deposition due to macrograin (boulder) interaction.
        • Tailing mostly fluid behavior.
      • Exciting!?@! USGS archival footage of debris flow dynamics: 1, 2, and 3 (Costa & Williams, USGS OFR 84-606, 1984).

    • Purely granular collisional interactions:
      Movie showing ongoing research by Grad student J. Estep and Prof. J. Dufek examining stress-chains associated with collisional interactions. Polarized light transmitted thorugh photo-elastic discs highlight 'force chains' of primarily normal stresses that develop during gravity-driven shear of low-friction granular materials.
      Such a flow of granular collisions is most likely near the flow head and unconstrianed sides where pore-pressure is minimal and deposition is dominant.

    From 11/20-22/13
    Earthquake Modeling:
    • Please go to the GTdef, forward modeling webpage.

    Geodynamics: Home |My Home | anewmangatech.edu | Updated: Wed Nov 20 11:59:25 EST 2013