(we are working on updating the research page!)

3D Printing Seismic Velocity Models for Seismic Experiments

We, for the first time, take advantage of 3D printing techniques to create physical models for seismic experiments.  This opens up unprecedented opportunities for understanding the seismic wave propagation in complex media—with small-scale heterogeneities, rough topography and interfaces, anisotropy, or pore fluids—which is crucial to various aspects of geophysics such as earthquake ground motion prediction, induced seismicity, and energy exploration.

To be presented at the upcoming AGU 2021 Meeting!

Ground Motions Simulated on a 3D Printed Model of the Los Angeles Basin

Sunyoung Park, Changsoo Shin, Younglib Kim, and Robert W. Clayton

S12A-08; Monday, 12/13/2021; 10:23 – 10:28 CST (Oral presentation)

Post-Seismic Deformation Following Deep Earthquakes

Most geodetic observations have been limited to shallow earthquakes since the amplitude of the surface deformation from deep events has been considered relatively small.  With data processing techniques, however, one can extract post-seismic signals from deep earthquakes at ~600-km depths.  This provides a new tool to understand the mantle viscosity structure which is one of the least constrained properties despite its importance in mantle dynamics.

To be presented at the upcoming AGU 2021 Meeting!

A Low-Viscosity Layer at the Bottom of the Mantle Transition Zone Inferred from the Post-Seismic Deformation Following a 600-km Deep Earthquake

Sunyoung Park, Jean-Philippe Avouac, Zhongwen Zhan and Adriano Gualandi

DI44B-05; Thursday, 12/16/2021, 15:05 – 15:10 CST (Oral presentation)

Near-Surface Structure Based on Body-Wave Polarization

Ground shaking depends strongly upon seismic wave speeds at the shallowest depths.  This work examines the polarization of seismic body waves to constrain near-surface wave speeds.

A new array method and its application to Mexico City was presented at the AGU 2020 Meeting:

[NS009-02] Array Analysis of Body-Wave Polarization Data: Application to Mexico City Seismic Networks 
Adrián Ruelas, Sunyoung Park and Francisco J Sanchez-Sesma

Upper-Mantle Discontinuities Based on Unwrapped Triplication Data

Constraining seismic properties of the 410- and 660-km discontinuities which delineate the mantle transition zone is crucial in understanding the mantle composition and convection dynamics. One approach to studying the transition zone is to use “triplicated” arrivals of seismic data. One of the challenging components in using triplication data, however, is to identify the three individual phases, since they arrive close in time and overlap with each other. Therefore, we analyze the Radon transform of the data, which unwraps the bowtie shape in the original data and separates the three phases. Based on the transformed data, the new methodology allows velocity jump, depth, and width of the discontinuities to be obtained.

Rupture Processes Based on 3-D Directivity

The directivity effect can provide important insights into the characteristics of the earthquake mechanism by estimating the rupture properties. We consider the directivity effect in three-dimension, i.e., parameterizing in dip and azimuth. Our analysis shows that examining not only the azimuthal variation but also the dip dependency is crucial for robust estimation of model parameters. Based upon the framework, we introduce an inversion scheme to obtain rupture properties; the duration, speed, dip, and azimuth of the rupture propagation.