Graduate Student (G5)
Harvard Seismology Group
Department of Earth and Planetary Sciences
I am interested in a variety of seismology topics including earth's shallow structure, deep structure, and earthquake characterization. I enjoy thinking about new or improved methodologies to study these topics.
For my Ph.D. projects, I am looking into earthquake rupture and seismic structure of near surface, mantle transition zone, and innercore boundary. I recently worked on an inversion scheme for rupture properties based on the 3-dimensional examination of earthquake directivity effect. The inversion is applied to estimate the rupture direction, length, propagation speed, and source duration of two deep earthquakes in the Kuril subduction zone, one of which shows complex rupture behavior. Currently, I am developing a new technique utilizing the polarization information of incoming body waves to obtain the velocity map near the surface. Near-surface seismic structure is crucial to our understanding of seismic hazards, since it controls the level of ground shaking. In addition, for the mantle transition zone, I am working on a new approach to study the upper mantle discontinuities from "triplication" data that are highly sensitive to discontinuity structures. This provides important constraints on the mantle composition and temperature in high spatial resolution compared to other types of seismic data containing relatively low frequency information. Finally, I am investigating the sharpness of the innercore boundary, which gives important insights into the dynamics of the innercore, convection mechanism of the outercore, and evolution and formation of earth.
During my M.Sc., I studied mathematical analyses of seismic inverse problems, particularly the convergence of full waveform inversion technique. One must understand whether the set-up of an inverse problem will let the result converge to the true solution or not before jumping into massive computation and generating tomographic images. By examining the inverse problem from the theory, one can learn how to ensure the convergence to the true solution and increase the convergence rate.
I have been very much enjoying looking at seismology from different angles. The theoretical perspective tells me how I can learn as much as possible from given data, while the real data perspective allows me to discover the real nature of earthquakes and earth structure. I appreciate the fact that what I enjoy working on can contribute to our knowledge of earthquakes and earthquake hazards, and potentially help people. At the same time, I take pleasure in improving our understanding of this planet, especially with integrated knowledge from other earth science disciplines.
Park, S., Ishii, M., 2015, Inversion for rupture properties based upon 3-D directivity effect and application to deep earthquakes in the Sea of Okhotsk region, Geophysical Journal International, 203, 1011-1025, doi: 10.1093/gji/ggv352.
Park, S., Qiu, L., De Hoop, M. V., Shin, C., 2012, On time-harmonic seismic data and blending in full waveform inversion, Proceedings of the Project Review, Geo-Mathematical Imaging Group, 1, 305-318.
Park, S., 2012, Convergence of full waveform inversion in the complex-frequency domain, M.Sc. Thesis.
Park, S., De Hoop, M. V., Calandra, H., Shin, C., 2011, Full waveform inversion: a diffuse optical tomography point of view, SEG Expanded Abstracts, 30, 2471-2475.
Park, S., Ha, W., Shin, C., Pyun, S., Calandra, H., 2010, A strategy for selecting the Laplace damping constants in the Laplace-domain inversion, based on the relationship between the Laplace damping constant and the detectable depth of a high-velocity structure, SEG Expanded Abstracts, 29, 993-997.