Snowshoeing in Denali National Park
Hi, I'm Bryant. I study earthquakes and I live in Alaska.

About Me

I'm a seismologist, which means I spend my days looking at wiggles on a screen. Typically these wiggles are recorded using very expensive slinkies (seismometers) buried in the ground, which shake and bounce due to earthquakes.

My research is in the field of seismic imaging (specifically, adjoint tomography), which means I use seismic waves to probe the structure of the Earth. Very simply, this involves generating fake wiggles using supercomputers and 3D models of the Earth. In a very roundabout way, I change parts of the model to try to line up the fake wiggles with the real wiggles, which gives me a better idea about the ground beneath our feet. Neat!

A wavefield simulation for a New Zealand earthquake

My research in a nutshell: [left] a computer simulation of seismic waves radiating away from an earthquake (black star) to be recorded by a seismometer (white triangle); [right] vertical shaking comparing the actual recording of this earthquake (black) and the simulated shaking (red). Note that time is sped up dramatically.

Research Highlights

Subducted Seamounts

Using our new model of the Earth's crust below the North Island of New Zealand, myself and co-authors suggested that we have imaged two previously-unrecognized seamounts (underwater mountains) subducted below the continent. Their presence may affect how we think about seismic activity within this region. This work was chosen for an Editor's highlight in Eos!

Adjoint Tomography in New Zealand

My doctoral research (now published as a pair of companion papers: 1, 2) involved seismic imaging of the Hikurangi subduction zone and tectonic interpretations of newly resolved structures in the crust below the North Island of New Zealand. We employed an imaging method known as adjoint tomography, which seeks to minimize differences between observed and simulated seismic waveforms.

NZ Adjoint TOMography model

One of the main products of my PhD was the New Zealand Adjoint TOMography model (NZ ATOM). NZ_ATOM_north is an adjoint tomography-derived velocity model for the North Island of New Zealand, and the adjacent Hikurangi subduction zone.

Broadband EAst COast Network

The Broadband EAst COast Network (BEACON) was a temporary deployment of 20 broadband seismic instruments in the central Hawke's Bay and Tararua regions. The network was deployed to supplement receiver coverage over the Hikurangi subduction interface.

Rotational Seismology

My master's work involved analysis of amplitudes from rotational ground motion sensors. Using a large catalog of global earthquakes, we empirically derived a rotational magnitude scale to understand the charactersitics of amplitude decay for rotation signals. I was also involved in development of a rotational seismology event database.

Resources

Codes

Pyatoa: a Python-based misfit assessment toolbox for adjoint tomography (main developer)
[Pyatoa documentation]

SeisFlows: automated full waveform inversion and adjoint tomography workflows (lead developer)
[SeisFlows documentation]

PySEP: seismic waveform and metadata download tool and record section plotter (lead developer)

Data

NZ_ATOM_NORTH: an adjoint tomography-derived 3D velocity model for the North Island of New Zealand

BEACON: publically available broadband waveform data from a temporary deployment in the North Island, NZ

CV

Positions

National Science Foundation Postdoctoral Fellow (2021 – 2023)
Active Tectonics and Crustal Structure of Northern Alaska
University of Alaska Fairbanks, Fairbanks, Alaska
Scientific Mentor: Carl Tape

Postdoctoral Researcher (May – September, 2021)
GNS Science, Lower Hutt, New Zealand

Education

PhD, Geophysics (2018 – 2021)
Adjoint tomography of the Hikurangi subduction zone and the North Island of New Zealand
Victoria University of Wellington, Wellington, New Zealand
Advisors: Yoshihiro Kaneko, John Townend

MSc, Geophysics (2015 – 2017)
Analysis of rotational motion amplitudes on local and global scales
Ludwig-Maximilians-Universität München & Technische Universität München, Munich, Germany
Advisors: Heiner Igel, Celine Hadziiannou, Stefanie Donner, Joachim Wassermann

BSc, Physics // Minor in German Studies (2011 – 2015)
Determining Love wave phase velocity through analysis of rotational ground motion
University of California Santa Barbara, Santa Barbara, California
Advisor: Toshiro Tanimoto

Select Publications

Strong upper-plate heterogeneity at the Hikurangi subduction margin (North Island, New Zealand) imaged by adjoint tomography
Bryant Chow, Yoshihiro Kaneko, Carl Tape, Ryan Modrak, Nick Mortimer, Stephen Bannister, John Townend
Journal of Geophysical Research: Solid Earth 127.1 (2022): e2021JB022865.

Evidence for deeply-subducted lower-plate seamounts at the Hikurangi subduction margin: implications for seismic and aseismic behavior
Bryant Chow, Yoshihiro Kaneko, John Townend
Journal of Geophysical Research: Solid Earth 127.1 (2022): e2021JB022866.

An automated workflow for adjoint tomography — Waveform misfits and synthetic inversions for the North Island, New Zealand
Bryant Chow, Yoshihiro Kaneko, Carl Tape, Ryan Modrak, John Townend
Geophysical Journal International 223.3 (2020): 1461-1480.

Love wave amplitude decay from rotational ground motions
Bryant Chow, Joachim Wassermann, Berhard S A Schuberth, Celine Hadziioannou, Stefanie Donner, Heiner Igel
Geophysical Journal International 218.2 (2019): 1336-1347.