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Researchers for the first time have used seismic sensors to track meltwater flowing through glaciers and into the ocean, an essential step to understanding the future of the world’s largest glaciers as climate changes. The University of Texas Institute for Geophysics...

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31

Career Center Open House
9:00 AM

Career Center Open House

  Start: August 31, 2015 at 9:00 am     End: August 31, 2015 at 12:00 pm
 Location:JGB 2.112 Career Center
 Contact:Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
All JSG students come by for bagels and coffee

SEP
03

De Ford Lecture Series: Bayani Cardenas
3:30 PM

Career Center Open House

  Start: August 31, 2015 at 9:00 am     End: August 31, 2015 at 12:00 pm
 Location:JGB 2.112 Career Center
 Contact:Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
All JSG students come by for bagels and coffee

De Ford Lecture Series: Bayani Cardenas

  Start: September 3, 2015 at 3:30 pm     End: September 3, 2015 at 5:00 pm
 Location:Boyd Auditorium
 Contact:Patrick Stafford, 512-471-5172

SEP
04

UTIG Seminar Series: Roger Buck, Lamont-Doherty Earth Observatory
10:30 AM

Career Center Open House

  Start: August 31, 2015 at 9:00 am     End: August 31, 2015 at 12:00 pm
 Location:JGB 2.112 Career Center
 Contact:Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
All JSG students come by for bagels and coffee

De Ford Lecture Series: Bayani Cardenas

  Start: September 3, 2015 at 3:30 pm     End: September 3, 2015 at 5:00 pm
 Location:Boyd Auditorium
 Contact:Patrick Stafford, 512-471-5172

UTIG Seminar Series: Roger Buck, Lamont-Doherty Earth Observatory

  Start: September 4, 2015 at 10:30 am     End: September 4, 2015 at 11:30 am
 Location:PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
 Contact:Luc Lavier, luc@ig.utexas.edu, 512-471-0455
 URL:Event Link
"The Mechanics of Extension in Very Different Areas of Plate Convergence: Reverse Subduction Exhuming Ultra-High Pressure Rocks in New Guinea, and Normal Faulting and Tsunami generation during the Tohoku-Oki Earthquake "

Abstract:

The controversy over the exhumation of ultra-high pressure (UHP) rocks centers on whether it involves rising of pieces of crust detached from subducted continental lithosphere or an entire subducted plate that undergoes "eduction", i.e. reverse subduction. A new thermomechanical model of continental subduction shows that these apparently contrasting mechanisms can occur together: Crust subducted deep enough is heated and weakened, causing limited diapiric rise, while crust subducted to shallower depths retains strength and is exhumed only by eduction. The model also shows for the first time how eduction followed by seafloor spreading can occur in a zone of regional convergence. This occurs spontaneously when subduction of buoyant crust causes a subduction zone to "lock up" in one place causing a new subduction zone to form in another. The model is consistent with many features of the youngest region of UHP rock exhumation on earth: the D'Entrecasteaux Islands of Papua New Guinea.

The Tohoku-oki earthquake was not only the costliest natural disaster in history it was the best monitored. Several observations suggest that the massive near-trench seafloor motion that produced the huge tsunami was linked to normal fault offset. Also, for the first time it was shown that a large subduction earthquake was followed by extensional aftershocks in a broad region of the upper plate. Inspired by the Tohoku data, researchers have searched for and found upper plate extensional aftershocks associated with several other subduction earthquakes that produced large tsunami. Numerical models show that a long-term reduction in slab dip can generate enough extensional stress to cause normal faulting over a broad region of the upper plate. During the inter-seismic period, when the subduction interface is locked, extensional fault slip is suppressed by the relative compression of the upper plate. The relief of compressional stresses during dynamic weakening of the megathrust triggers a release of bending-related extensional strain energy. This mechanism is analogous to the breaking of a pre-stressed concrete beam supporting a bending moment when the compressional pre-stress is removed.


SEP
10

De Ford Lecture Series: Marc Hesse
3:30 PM

Career Center Open House

  Start: August 31, 2015 at 9:00 am     End: August 31, 2015 at 12:00 pm
 Location:JGB 2.112 Career Center
 Contact:Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
All JSG students come by for bagels and coffee

De Ford Lecture Series: Bayani Cardenas

  Start: September 3, 2015 at 3:30 pm     End: September 3, 2015 at 5:00 pm
 Location:Boyd Auditorium
 Contact:Patrick Stafford, 512-471-5172

UTIG Seminar Series: Roger Buck, Lamont-Doherty Earth Observatory

  Start: September 4, 2015 at 10:30 am     End: September 4, 2015 at 11:30 am
 Location:PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
 Contact:Luc Lavier, luc@ig.utexas.edu, 512-471-0455
 URL:Event Link
"The Mechanics of Extension in Very Different Areas of Plate Convergence: Reverse Subduction Exhuming Ultra-High Pressure Rocks in New Guinea, and Normal Faulting and Tsunami generation during the Tohoku-Oki Earthquake "

Abstract:

The controversy over the exhumation of ultra-high pressure (UHP) rocks centers on whether it involves rising of pieces of crust detached from subducted continental lithosphere or an entire subducted plate that undergoes "eduction", i.e. reverse subduction. A new thermomechanical model of continental subduction shows that these apparently contrasting mechanisms can occur together: Crust subducted deep enough is heated and weakened, causing limited diapiric rise, while crust subducted to shallower depths retains strength and is exhumed only by eduction. The model also shows for the first time how eduction followed by seafloor spreading can occur in a zone of regional convergence. This occurs spontaneously when subduction of buoyant crust causes a subduction zone to "lock up" in one place causing a new subduction zone to form in another. The model is consistent with many features of the youngest region of UHP rock exhumation on earth: the D'Entrecasteaux Islands of Papua New Guinea.

The Tohoku-oki earthquake was not only the costliest natural disaster in history it was the best monitored. Several observations suggest that the massive near-trench seafloor motion that produced the huge tsunami was linked to normal fault offset. Also, for the first time it was shown that a large subduction earthquake was followed by extensional aftershocks in a broad region of the upper plate. Inspired by the Tohoku data, researchers have searched for and found upper plate extensional aftershocks associated with several other subduction earthquakes that produced large tsunami. Numerical models show that a long-term reduction in slab dip can generate enough extensional stress to cause normal faulting over a broad region of the upper plate. During the inter-seismic period, when the subduction interface is locked, extensional fault slip is suppressed by the relative compression of the upper plate. The relief of compressional stresses during dynamic weakening of the megathrust triggers a release of bending-related extensional strain energy. This mechanism is analogous to the breaking of a pre-stressed concrete beam supporting a bending moment when the compressional pre-stress is removed.


De Ford Lecture Series: Marc Hesse

  Start: September 10, 2015 at 3:30 pm     End: September 10, 2015 at 5:00 pm
 Location:Boyd Auditorium
 Contact:Patrick Stafford, 512-471-5172

more →

Alumni - Tailgates, reunions and continuing education with your fellow alums
Tailgates, reunions and continuing education with your fellow alums
New Salt Tectonics Complex - Honoring Martin Jackson, raising funds towards a newly renovated Salt Tectonics Modeling Complex
Honoring Martin Jackson, raising funds towards a newly renovated Salt Tectonics Modeling Complex
Geoscience Education - Summit on Future of Undergraduate Geoscience Education: Summary Report & Survey
Summit on Future of Undergraduate Geoscience Education: Summary Report & Survey
GeoFORCE Challenge Match - This endowment has launched to ensure the continuation of this critical program
This endowment has launched to ensure the continuation of this critical program
Work at JSG - The Jackson School is hiring. Apply online.
The Jackson School is hiring. Apply online.
Find a Supervisor - Grad students work with over 70 scientists in 9 research disciplines
Grad students work with over 70 scientists in 9 research disciplines
 
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