About me

I am a postdoctoral scholar at the University of Washington, United States, working with Professor David Schmidt. My postdoctoral research focuses on estimating the hazards of coastal land subsidence from future earthquakes in Pacific Northwest. This project is a part of the NSF-funded Cascadia Coastlines and Peoples Hazards Research Hub (Cascadia CoPes Hub). Outside of my office, I am a proficient drummer, playing jazz-funk, pop and rock!

I use satellite geodesy techniques and computational modeling tools to study crustal deformation and understand the underlying physical processes. This includes phenomena such as tectonics, earthquakes, human activities (e.g., groundwater pumping), and changes in surface hydrologic loads.

What I do

Skills/Tools

Horizontal GNSS displacements data (4-month).

Global Navigation Satellite System (GNSS)

Using GNSS position time series I investigate crustal deformation patterns. I developed an automated algorithm that (1) downloads GNSS time series data (Blewitt et al., 2018; Link), (2) preprocesses them (correct steps and eliminate outliers), (3) calculates velocities, (4) plots the corrected time series, and (5) obtains 4-month displacements (in a North American frame).

Interferometric Synthetic Aperture RADAR (InSAR)

I also use InSAR data to model crustal deformation. To process this InSAR image, I used ISCE2 software (Link) and two pieces of ESA's Sentinel-1 SLC data from before and after the 2019 Ridgecrest, California, earthquake sequence (descending track 71; downloaded from ASF DATA Search [Link]).

Unwrapped interferogram for the 2019 Ridgecrest, California, earthquake sequence. Red indicates the land is moving away from the satellite.

The Sparse Program

Continuum Mechanics

This inversion code processes GNSS data, focal mechanism solutions and/or Quaternary fault information (strike, dip, and rake) to compute horizontal strain rates, rotations, continuous velocities, etc., treating the Earth's crust as a continuum material (Haines et al., 1998, Haines and Holt, 1993). I am thankful to my PhD advisor, William E. Holt, and my colleague Dr. Alireza Bahadori for their invaluable guidance in mastering the Sparse Program.

A modeled tectonic strain rate field for southern California. The background represents the second invariant of the strain rate field.

I use Poly3D to calculate the Earth's elastic half-space responses to a given earthquake source. This tool can also be used to invert geodetic data (e.g., InSAR, GNSS, and leveling data) for fault parameters (slips, rakes, slip deficits, etc.). For more details, see this thesis (Thomas, 1993; Link). I am grateful to my postdoctoral advisor, Professor David Schmidt, for his assistance in mastering this program.

Poly3D

A boundary-element method 

A 3D fault geometry (Slab2.0; Hayes et al., 2018) used for earthquake rupture simulations.

I use two programs to quantify the spherical Earth's elastic responses to surface mass loads (e.g., ice sheets, soil-moistures, snow, etc). LoadDef is a Python-based program (Martens et al, 2019; Link). Alternatively, I use JPL's ISSM program based on MATLAB (Adhikari et al., 2016; Link). A python-based package is also available. 

LoadDef & JPL's ISSM

The white vectors illustrate the Earth's elastic horizontal responses to changes in surface hydrologic loading (soil moisture and snow; NLDAS [Link])

VISCO 2.5D

I am currently learning a new computational tool to study mechanisms of post-seismic deformation following the M7.5 2024 Noto, Japan, earthquake. This is a Fortran-based program written by Dr. Fred. F. Pollitz. For more details, see his paper (Pollitz, 2015; [Link]). I appreciate Dr. Fred Pollitz's assistance with installing this program and guiding me through the codes.

These figures are from the VISCO2.5D version 1.o Tutorial provided by Fred. F. Pollitz of USGS.

A New Joint Inversion Algorithm of InSAR and GNSS

InSAR and GNSS providing highly complementary measurements

This inversion algorithm inverts InSAR and GNSS data to calculate horizontal strain rates, continuous 3D surface velocities, and rotations, and horizontal gradients in the vertical velocity field, among other parameters. My colleagues and I are preparing for two manuscripts to submit on this new methodology and its applications. This project received support from the NASA FINESST award!