Research Interests

I am interested in developing both theoretical and observational tools to study earthquakes and Earth's interior. Currently, I am looking into earthquake source theories. Conventional approach assumes that faults are buried within homogeneous media. However, faults are often bimaterial, i.e., the material on one side of the fault differs from the other side. Some well-known examples include the San Andreas fault and subduction zone interfaces. In addition, faults may not be fully buried but rupture through discontinuities such as the seafloor or free surface. Understanding how the bimateriality and discontinuity rupture affect the seismograms can in turn allow for a better source characterization using seismic observations.

Previously, I investigated the propagations of body waves in the presence of a non-hydrostatic or deviatoric initial stress. This type of stress is commonly observed inside the Earth’s upper lithosphere yet typically ignored in seismic-wave propagation theories. Finally, I developed a novel automatic phase-picking algorithm for processing seismic array data. This method is applied to identify core-reflected P waves (PcP) recorded by the Hi-Net array in Japan.


Education

2021-Present: Ph.D Candidate in Earth and Planetary Sciences, Harvard University, Cambridge, MA

2019-2021: M.S. in Data Science, Harvard University, Cambridge, MA

2015-2019: B.A. in Geology-Physics/Mathematics-Honors and Applied Mathematics, Brown University, Providence, RI


Teaching Experience (see full CV for more details)

FS23I: GeoScifi Movies, Harvard University, Cambridge, MA (Fall 2022 and 2024)

E-PSCI 165/265: Introduction to Seismology, Harvard University, Cambridge, MA (Fall 2023)


Mentoring Experience (see full CV for more details)

SPHEER peer mentor, Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA (Summer 2023 and 2024)

EPS Short-Term Program mentor, Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA (August 2023)


Awards

American Geophysical Union Outstanding Student Presentation Award (2022)

Brown University Undergraduate Teaching and Research Award (2017)


Publications (*In. Prep.)

Geng, Y., & Ishii, M. (2024). Body-wave speeds and polarizations in the presence of an initial deviatoric stress. Geophysical Journal International, 239(3), 1943-1952, doi:10.1093/gji/ggae369.

*Geng, Y. and Ishii, M. (in prep.). A Novel Cross-Correlation-Based Automatic Phase-Picking Algorithm for Seismic Array Data and its Application to PcP Arrivals


Presentations (*Invited)

Geng, Y. & Ishii, M. (2024). Source Parameter Determination of Bimaterial Faults through Long-Period Seismic Waves, Abstract S33A-3276 presented at 2024 AGU Fall Meeting, Washington, D.C., 9 – 13 Dec.

*Geng, Y. (2024). Why Are Current Earthquake Studies on the San Andreas Fault Insufficient?, given at the Department of Earth, Environmental and Planetary Sciences at Brown University, 1 Oct.

Geng, Y. & Ishii, M. (2024). Source Parameter Determination of Bimaterial Faults through Long-Period Seismic Waves, Poster 011 presented at 2024 SCEC Annual Meeting, Palm Springs, CA, 8 – 11 Sept.

Geng, Y. and Ishii, M. (2023). Anisotropy in the Presence of an Initial Deviatoric Stress, Abstract DI42A-09 presented at 2023 AGU Fall Meeting, San Francisco, CA, 11 – 15 Dec.

Geng, Y. and Ishii, M. (2023). Heterogenous Structures beneath Japan Illuminated by Core-Reflected Seismic Waves, Abstract DI14A-03 presented at 2023 AGU Fall Meeting, San Francisco, CA, 11 – 15 Dec.

Geng, Y. and Ishii, M. (2022). A Novel Cross-Correlation-Based Automatic Phase-Picking Algorithm for Seismic Array Data and its Application to PcP Arrivals, Abstract S43B-06 presented at 2022 AGU Fall Meeting, Chicago, IL, 12 – 16 Dec.

Geng, Y., MacDougall, J., West, J. M., and Fischer, K. M. (2019). Seismic Anisotropy and Mantle Deformation beneath the Hindu Kush-Pamir Region, Abstract DI21B-0029 presented at 2019 AGU Fall Meeting, San Francisco, CA, 9 – 13 Dec.