Ethan Williams's Home Page

Ethan F. Williams

I am currently a postdoc at the University of Washington working with Brad Lipovsky and Marine Denolle. I recently completed my Ph.D. in geophysics at the Caltech Seismo Lab, advised by Zhongwen Zhan. I apply fiber-optic sensing to problems in environmental/engineering seismology and physical oceanography. My research interests include wave physics, ocean-solid Earth interaction, and seismic ambient noise.

News:

• (2023-06-30)  We have a new preprint out on EarthArXiv showcasing low-frequency DAS observations of internal wave and tide dynamics in the Strait of Gibraltar and offshore the island of Gran Canaria.
• (2023-01-15)  I moved to the University of Washington.
• (2022-11-09)  Our paper tracking the temporal variability of a building's natural frequencies in response to earthquake and environmental forcing across a 20-year period was recently published in The Seismic Record. Read it here.
• (2022-11-02)  I defended my Ph.D. thesis. Read it here.
• (2022-09-14)  I recently gave a seminar for the USGS Earthquake Science Center. You can listen to the recording here.
• (2022-06-24)  I received a 2022 SSA Student Presentation Award for my talk "Continuous seismic monitoring of a building over 20 years."
• (2022-05-15)  Our paper on ocean surface gravity waves and DAS was recently published in JGR: Oceans. Read it here.

Research:

About me:

• 2023- GHI Postdoctoral Scholar, University of Washington

• 2022 Ph.D. in Geophysics, Caltech
• 2019 M.S. in Geophysics, Caltech
• 2017 B.S. in Geophysics, Stanford (minor in Geological Sciences)
• 2017 B.A. in Music, Stanford

Publications:

Submitted

1. Williams, E.F., A. Ugalde, H.F. Martins, C. Becerril, J. Callies, M. Claret, M.R. Fernandez-Ruiz, M. Gonzalez-Herraez, S. Martin-Lopez, J.L. Pelegri, K.B. Winters, and Z. Zhan (in review) Fiber-optic observations of internal waves and tides. Submitted to JGR: Oceans, April 2023.
2. Biondi, E., W. Zhu, J. Li, E.F. Williams, and Z. Zhan (in review) An upper-crust lid over the Long Valley magma chamber. Submitted to Science Advances, May 2023.

2023

3. Fang, J., Y. Yang, Z. Shen, E. Biondi, X. Wang, E.F. Williams, M.W. Becker, D. Eslamian, and Z. Zhan (2023) Directional sensitivity of DAS and its effect on Rayleigh-wave tomography: A case study in Oxnard, California. Seismological Research Letters, 94 (2A), pp. 887-897.
4. Biondi, E., X. Wang, E.F. Williams, and Z. Zhan (2023) Geolocalization of large-scale DAS channels using a GPS-tracked moving vehicle. Seismological Research Letters, 94 (1), pp. 318-330.

2022

5. Williams, E.F., T.H. Heaton, Z. Zhan, and V.R. Lambert (2022) Variability in the natural frequencies of a nine-story concrete building from seconds to decades. The Seismic Record 2 (4), pp. 237-247.
6. Williams, E.F. (2022) Listening to the seafloor through optical fibers. Physics Today 75 (10), pp. 70-71.
7. Williams, E.F., Z. Zhan, H.F. Martins, M.R. Fernandez-Ruiz, S. Martin-Lopez, M. Gonzalez-Herraez, and J. Callies (2022) Surface gravity wave interferometry and ocean current monitoring with ocean-bottom DAS. Journal of Geophysical Research: Oceans, 127 (5), e2021JC018375.
8. Yang, Y., J.W. Atterholt, Z. Shen, J.B. Muir, E.F. Williams, and Z. Zhan (2022) Sub-kilometer correlation between near-surface structure and ground motion measured with distributed acoustic sensing. Geophysical Research Letters, 49, e2021GL096503.

2021

9. Wang, X., Z. Zhan, E.F. Williams, M. Gonzalez-Herraez, H.F. Martins, and M. Karrenbach (2021) Ground vibrations recorded by fiber-optic cables reveal traffic response to COVID-19 lockdown measures in Pasadena, California. Communications Earth & Environment 2 (160).
10. Williams, E.F., M.R. Fernandez-Ruiz, R. Magalhaes, R. Vanthillo, Z. Zhan, M. Gonzalez-Herraez, and H.F. Martins (2021) Scholte wave inversion and passive source imaging with ocean-bottom DAS. The Leading Edge 40 (8), pp. 576-583.
11. Fernandez-Ruiz, M.R., H.F. Martins, E.F. Williams, C. Becerril, R. Magalhaes, L.D. Costa, S. Martin-Lopez, S. Jia, Z. Zhan, and M. Gonzalez-Herraez (2022) Seismic monitoring with distributed acoustic sensing from the near-surface to the deep oceans. Journal of Lightwave Technology 40 (5), pp. 1453-1463.
12. Li, Z., Z. Shen, Y. Yang, E.F. Williams, X. Wang, and Z. Zhan (2021) Rapid response to the 2019 Ridgecrest earthquake with distributed acoustic sensing. AGU Advances 2, e2021AV000395.

2020

13. Fernandez-Ruiz, M.R., M.A. Soto, E.F. Williams, S. Martin-Lopez, Z. Zhan, M. Gonzalez-Herraez, and H.F. Martins (2020) Distributed acoustic sensing for seismic activity monitoring. APL Photonics 5 (3), 030901.
14. Wang, X., E.F. Williams, M. Karrenbach, M. Gonzalez-Herraez, H.F. Martins, and Z. Zhan (2020) Rose Parade seismology: Signatures of floats and bands on optical fiber. Seismological Research Letters 91, pp. 2395-2398.

2019

15. Williams, E.F., M.R. Fernandez-Ruiz, R. Magalhaes, R. Vanthillo, Z. Zhan, M. Gonzalez-Herraez, and H.F. Martins (2019) Distributed sensing of microseisms and teleseisms with submarine dark fibers. Nature Communications 10 (5778).
16. Gurnis, M., H. Van Avendonk, S.P.S. Gulick, J.M. Stock, R. Sutherland, E. Hightower, B. Shuck, J. Patel, E.F. Williams, D. Kardell, E. Herzig, B. Idini, K. Graham, J. Estep, and L. Carrington (2019) Incipient subduction at the contact with stretched continental crust: the Puysegur Trench. Earth and Planetary Science Letters 520, pp. 212-219.

2018

17. Williams, E.F., C.M. Castillo, S.L. Klemperer, N. Raineault, and L. Gee (2018) Sycamore Knoll: A wave-planed pop-up structure in a sinistral-oblique thrust system, Southern California Continental Borderland. Deep Sea Research, Part II: Topical Studies in Oceanography 150, pp. 132-145.