Title

Seismic Anisotropy Beneath Alaska from Shear Wave Splitting Study

Presenter Information

Junzhe Sun

Department

Geosciences and Geological and Petroleum Engineering

Major

Geology and Geophysics

Research Advisor

Gao, Stephen S.

Advisor's Department

Geosciences and Geological and Petroleum Engineering

Funding Source

Missouri S&T Opportunities for Undergraduate Research Experiences (OURE) Program

Abstract

Seismic azimuthal anisotropy beneath the Aleutian-Alaska Trench is studied using all teleseismic shear wave records archived at the IRIS Data Management Center. We have obtained approximately 2400 high-quality splitting measurements, selected by visual inspection of over 12,000 records of SKS, SKKS and PKS phases. Wave traveling northwest of the 100km slab contour shows overall uniform fast polarization direction parallel to the strike of the trench, suggesting along strike flow in the thicker part of mantle wedge possibly caused by North America Plate motion to the southwest. Wave traveling southeast of the 100km contour with their piercing point falling between 100-50 km contours shows fast polarization directions orthogonal to the strike of the trench. A gradual turning in fast direction around the slab edge is also observed. The splitting pattern confirms a numerical model which involves a 3D toroidal mantle flow around the north-eastern edge of the subducting Aleutian slab.

Biography

Junzhe is a senior student studying Geophysics advised by Dr. Stephen Gao. He grew up in the second largest oil field of China, Shengli Oil Field. He found seismology intriguing since his childhood, thanks to his father, a petroleum engineer, who first introduced him to exploration geophysics. Junzhe was admitted to China University of Petroleum-East China (hereinafter referred to as “CUP”) as a EE major in 2007, one year after which he switched his major to Geophysics due to the influence of the devastating 2008 Sichuan Earthquake. He transferred from CUP to Missouri S&T in 2010 and will be graduating in May 2012 with a BS degree in Geophysics. Junzhe has worked as a research assistant in Geophysics and a teaching assistant in Structural Geology as well as Physical Mineralogy and Petrology. He has also served as the president of Chinese Students and Scholars Association at Missouri S&T from 2011 to 2012. After graduation, he will go to Stanford University to pursue Ph.D degree in Geophysics.

Research Category

Sciences

Presentation Type

Poster Presentation

Document Type

Poster

Location

Upper Atrium/Hallway

Presentation Date

10 Apr 2012, 9:00 am - 11:45 am

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Apr 10th, 9:00 AM Apr 10th, 11:45 AM

Seismic Anisotropy Beneath Alaska from Shear Wave Splitting Study

Upper Atrium/Hallway

Seismic azimuthal anisotropy beneath the Aleutian-Alaska Trench is studied using all teleseismic shear wave records archived at the IRIS Data Management Center. We have obtained approximately 2400 high-quality splitting measurements, selected by visual inspection of over 12,000 records of SKS, SKKS and PKS phases. Wave traveling northwest of the 100km slab contour shows overall uniform fast polarization direction parallel to the strike of the trench, suggesting along strike flow in the thicker part of mantle wedge possibly caused by North America Plate motion to the southwest. Wave traveling southeast of the 100km contour with their piercing point falling between 100-50 km contours shows fast polarization directions orthogonal to the strike of the trench. A gradual turning in fast direction around the slab edge is also observed. The splitting pattern confirms a numerical model which involves a 3D toroidal mantle flow around the north-eastern edge of the subducting Aleutian slab.