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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...

SEP
03

De Ford Lecture Series: Bayani Cardenas
3:30 PM

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

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

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

SEP
11

UTIG Seminar Series: Matthew Siegler, Planetary Science Institute
10:30 AM

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

UTIG Seminar Series: Matthew Siegler, Planetary Science Institute

  Start: September 11, 2015 at 10:30 am     End: September 11, 2015 at 11:30 am
 Location:PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
 Contact:Krista Soderlund, krista@ig.utexas.edu, 512-471-0449
 URL:Event Link
"Polar Ice and Physical Evidence of Lunar True Polar Wander"

Abstract:

The earliest dynamical and thermal history of the Moon is not well understood. Surprisingly, this history may be recorded by the hydrogen deposits near the Lunar poles. These deposits (likely water ice) can only survive if they remain in permanent shadow. If the Moon's orientation has changed, so have the location of the shadowed regions. The polar hydrogen deposits have been mapped by orbiting neutron spectrometers, and their observed spatial distribution does not match the expected distribution of water ice inferred from present-day lunar temperatures. This is in stark contrast to the volatile distribution observed within a similar thermal environment at Mercury's poles. Here we show that polar hydrogen preserves evidence that the Moon's spin axis has shifted - the hydrogen deposits are antipodal, displaced equally from each pole along opposite longitudes. From the direction and magnitude of the inferred reorientation, and analysis of the lunar figure, we find that this change in the spin pole, known as true polar wander, was caused by a low-density thermal anomaly beneath the Procellarum region. Radiogenic heating within this province resulted in major mare volcanism and altered the density structure of the Moon, changing its moments of inertia. This resulted in true polar wander consistent with the observed remnant polar hydrogen. This anomaly still exists and partly controls the current orientation of the Moon. Procellarum was most geologically active early in lunar history, implying that polar wander initiated long ago and that a large portion of the measured polar hydrogen is ancient, recording early delivery of water to the inner solar system. This hypothesis not only provides a uniquely viable explanation for the antipodal distribution of lunar polar hydrogen, but also connects polar volatiles to the geologic and geophysical evolution of the Moon and the bombardment history of the early solar system.

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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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