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3:30 pm - De Ford Lecture Series: Jim Van Orman, Case Western University

De Ford Lecture Series: Jim Van Orman, Case Western University

  Start: December 3, 2015 at 3:30 pm     End: December 3, 2015 at 5:00 pm
 Location:Boyd Auditorium
 Contact:Patrick Stafford, 5124715172

10:30 am - UTIG Seminar Series: GRA Presenter, Maureen Walton

UTIG Seminar Series: GRA Presenter, Maureen Walton

  Start: December 4, 2015 at 10:30 am     End: December 4, 2015 at 11:30 am
 Location:PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
 Contact:Nick Hayman, hayman@ig.utexas.edu, 512-471-7721
 URL:Event Link
Presentation title: "Revisiting the 1899 Earthquakes of Yakutat Bay, Alaska"

North of Yakutat Bay in southeastern Alaska, the subducting Yakutat Block intersects with the Fairweather transform fault system. A series of large earthquakes occurred in the region in September of 1899, including a Mw 8.2 event on 10 September that resulted in >14 m of coseismic uplift and a 6 m tsunami in Yakutat Bay. Despite recurrence risk of the 1899 or similar events in the region, the fault(s) that ruptured in 1899 remain unidentified. Previous efforts to map active Yakutat Bay faults carried out by Plafker and Thatcher (2008) used post-1899 bedrock uplift measurements to infer the location of potentially important structures, including the Esker Creek and Bancas Point thrusts. As measurement error was not assessed in their study, we revisit the uplift measurements by quantifying uncertainty; effects of glacial isostatic adjustment (GIA), in particular, are significant. We also combine new seismic reflection data with existing topography, bathymetry, GPS, and satellite photo data to update earlier fault maps. Our reevaluation of uplift measurements suggests that primary slip and uplift during the 10 September earthquake was limited to northwest of Yakutat Bay. Additionally, a high-resolution seismic reflection survey we conducted in Yakutat Bay during August 2012 constrains faulting to on- or near-shore based on the absence of bay-crossing faults. Collectively, our results imply that predominantly strike-slip and transpressive horsetail-type faults are southeast of Yakutat Bay, with compressional structures related to Yakutat Block subduction/collision to the northwest. We interpret the 10 September 1899 event to be the result of complex rupture somewhere within the Yakutat subduction/collision system. Based on our updated map of coseismic uplift and fault structure, we favor a rupture model where primary slip occurred along the Esker Creek system locally with possible induced coseismic slip along the neighboring Boundary transpressive fault system. Future work targets imaging offshore connections between Yakutat Bay fault systems and the Pamplona Zone subduction deformation front, which will assist with assessing potential hazards related to recurrence of an 1899-type event.

10:30 am - UTIG Seminar: Frédérique Leclerc, Earth Observatory of Singapore

UTIG Seminar: Frédérique Leclerc, Earth Observatory of Singapore

  Start: December 11, 2015 at 10:30 am     End: December 11, 2015 at 11:30 am
 Location:PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
 Contact:Fred Taylor, fred@ig.utexas.edu, 512-471-0453
 URL:Event Link
"Long-Term Permanent Deformation of Overriding Plates: Markers to Better Understand Convergence Accommodation and the Seismic Behavior of Subduction Zones"


Where convergence is slow and seismicity rate is low, convergent margins’ seismic hazard is usually not well understood, due to poor constraints on the way convergence is accommodated. In such cases, geodesic measurements often fail to characterize the megathrust’s seismic behavior. Therefore, long-term upper-plate deformation constitutes valuable information that reveals how the convergence is accommodated and what processes are taking place along the active margin.

The slow and apparently uncoupled Lesser Antilles (L.A.) subduction zone and the SE Indonesian arc-continent collision margin are such plate boundaries - relatively seismically quiet during the historical period, and where first-order questions are still unresolved: how is the convergence accommodated? What processes is taking place along the margin? What and where are the active tectonic structures? What are their geometry and kinematics?

Both margins are located at latitudes where reefs are growing and record long-term vertical coastal movements. By studying the stratigraphy and morphology of emerged but also submerged reef complexes, through marine geophysical data and field investigation, as well as by modeling the reef deposition, we can determine the vertical movements of the coasts over several 100 kyr. Both along- and across a trench, the geometry and kinematics of upper-plate deformation allow us to determine and interpret active structures and megathrust-related processes that accommodate the convergence. In the L.A., we will further compare the long-term deformation to the short-term (seismic cycle related) deformation to question our present understanding of the seismic behavior of the subduction zone.

12:00 pm - Alumni Reception during AGU in San Francisco

Alumni Reception during AGU in San Francisco

  Start: December 16, 2015 at 12:00 pm     End: December 16, 2015 at 2:00 pm
 Location:ThirstyBear Brewing Co. - 661 Howard Street in San Francisco
 Contact:Kristen Tucek, ktucek@jsg.utexas.edu, 512-471-2223