Ethan Williams

Seismologist, postdoc @UW_ESS

[Ettore Biondi @BiondiEttore]

New paper in @ScienceAdvances
Using DAS deployed on existing telecom cables, we created new images from the Long Valley caldera highlighting a clear upper-crust lid confining the deep magma chamber: https://t.co/R95UwsuAi2

[Maddie Smith (she/her) @madmscientist]

🚨We can measure waves along 10s of km of coastline with incredibly high resolution using seafloor telecommunication cables! We show an application of this for understanding waves in sea ice in our new GRL open-access publication: https://t.co/ganBFLEqAm 1/

[Ethan Williams @EthanFWilliams]

@FabriceArdhuin @JGROceans There weren’t any clear infragravity wave signals in these datasets, but some DAS data we collected on the Oregon shelf in 2021 show them—something I’m working on now. Interestingly the infragravity waves radiating off the shelf appear stronger than the incident waves.

[Ethan Williams @EthanFWilliams]

I'm excited to share a new paper out in @JGROceans with wonderful coauthors from UAH, ICM, Caltech, and SIO. We look at long-period signals from internal waves and tides in ocean-bottom DAS datasets from the Strait of Gibraltar and Gran Canaria. https://t.co/EGZy4M0WTq 1/11

[Ethan Williams @EthanFWilliams]

Even though there are probably still temperature residuals, the 14-day stability at microstrain sensitivity demonstrated here is extremely promising for applications of DAS in seafloor geodesy and tsunami monitoring. 11/11

[Ethan Williams @EthanFWilliams]

With all these temperature signals, what about strain? We attempted to isolate the smaller strain signal from pressure loading by the longer-wavelength linear tide by spatially averaging the data, and the result matches predictions including the fortnightly component. 10/11

[Zhongwen Zhan @ZhongwenZhan]

New paper from @EthanFWilliams: seafloor DAS observations of internal waves and tides. "... DAS possesses sufficient long-period sensitivity for seafloor geodesy and tsunami monitoring if ocean temperature variations can be separated." 🤯
https://t.co/1ISgurHNxs

[JASA Express Letters @ASA_JASAEL]

EDITOR'S PICK

A public domain dataset from distributed acoustic sensing (DAS) experiment on the @oceanobserv regional cabled array demonstrates the potential of DAS for low frequency acoustic monitoring: https://t.co/cfAh8qFbLj

@williamwilcock @ShimaAbadi @brad_lipovsky

[Caltech Seismo Lab @CaltechSeismo]

@BiondiEttore, Weiqiang Zhu, @jxli42, @EthanFWilliams, and @ZhongwenZhan today at 11:30 AM will present the latest tomography results from their long-term large-scale distributed acoustic sensing experiment in the Long Valley Caldera! For more info visit: https://t.co/ytK8N2F0xM

[SSA @SeismoSocietyAm]

Caltech Hall is Getting Stiffer, according to a study out today in The Seismic Record
@CaltechSeismo
https://t.co/TXRlKo0H98

[Ethan Williams @EthanFWilliams]

(5) This was only done with one station so we can't decompose effects from different components of the structure/foundation/soil system. Is Caltech Hall unique or do all concrete buildings exhibit enormous variability in apparent stiffness? Lots of potential for future work! 11/n

[Ethan Williams @EthanFWilliams]

New paper out today in #TheSeismicRecord looking at 20 years of data from a nine-story concrete building w/ Tom Heaton, @ValereLambert, @ZhongwenZhan. TLDR: the building's apparent stiffness varies 20+% over scales from seconds to decades. 1/n https://t.co/ddUBWFwBEU

[Ethan Williams @EthanFWilliams]

(4) Linear, time-invariant elasticity (below the yield point) is a ubiquitous assumption in engineering, from using intensity measures like spectral acceleration to (even nominally nonlinear) finite element models. We show that elasticity is nonlinear and time-dependent. 10/n