The Potential of DAS in Teleseismic Studies: Insights From the Goldstone Experiment

Yu, Chunquan; Zhan, Zhongwen; Lindsey, Nathaniel J.; Ajo‐Franklin, Jonathan; Robertson, Michelle

doi:10.1029/2018gl081195

Cited by 110 publications

(92 citation statements)

References 29 publications

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“…According to our results, the broadband DAS response is validated against a high‐quality broadband seismometer over the range from 1–120 s. In terms of frequency range, DAS is found to be as broadband as the broadband seismometer used for calibration. Usable teleseismic energy falls off at periods longer than 120 s, but the DAS continues to show energy in time‐frequency analysis down to 300 s. This is more than twice as long as the longest period DAS signals previously documented by Becker et al () in a hydrogeological pump test and in earthquake studies on dark fiber DAS arrays (Ajo‐Franklin et al, ; Yu et al, ). One reason for this may be the DAS data processing approach employed here in which we stack over a window of 50 m, all falling inside of the seismic wave's long coherence length, mitigating uncorrelated channel noise and improving recovery of low frequency signals.…”

Section: Discussionmentioning

confidence: 77%

“…Here, we restrict our focus to a single commercial instrument, the Silixa iDAS (Version 2), which is a time domain, single‐pulse, phase‐based DAS instrument (Parker et al, ). This particular DAS instrument is among the more widely utilized in the field of earthquake seismology (Ajo‐Franklin et al, ; Jousset et al, ; Lindsey et al, ; Wang et al, ; Yu et al, ). The following discussion of the relationship between ground motion and DAS data is a synthesis of many works including Bakku (), Bóna et al (), Dean et al (), Grattan and Meggitt (), Hartog (), Kreger et al (), Karrenbach et al (), Masoudi and Newson (), Posey et al (), Parker et al (), and Willis et al (), as well as U.S. patents on the technology (Farhadiroushan et al, ).…”

Section: The Das Measurement Principlementioning

confidence: 99%

“…The long‐period frequency response of the DAS method has been demonstrated in recordings of teleseismic earthquakes (Ajo‐Franklin et al, ; Jousset et al, ) and laboratory and field pump tests (Becker et al, ; Becker & Coleman, ). To date, the longest period earthquake signal observed with DAS used a dark fiber DAS array in the Mojave Desert to capture propagating surface waves down to

T = 200

s (Yu et al, ). Recently, Becker and Coleman () showed that DAS can record tidal periods (

T = 4.3 \times 1 0^{4}

s) in a laboratory setting, albeit with a strain amplitude

7 \times 1 0^{3}

times greater than the solid Earth tide.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, DAS studies have focused on seismic wave phase information, which is sufficient to model seismic wavefield velocities, for example, in vertical seismic profiling (Daley et al, ; Mateeva et al, ), ambient noise velocity inversions (Ajo‐Franklin et al, ; Dou et al, ; Zeng et al, ), and earthquake phase identification (Ajo‐Franklin et al, ; Jousset et al, ; Lindsey et al, ; Yu et al, ). However, true ground motion amplitudes are necessary for many other seismological processing tasks, including full‐waveform inversion, AVO analysis, moment tensor inversion, and attenuation analysis, which the DAS community will likely investigate in the near future (Cole et al, ; Paitz et al, ).…”

Section: Introductionmentioning

confidence: 99%

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On the Broadband Instrument Response of Fiber‐Optic DAS Arrays

2020

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Distributed Acoustic Sensing (DAS) is a novel tool in array seismology that measures the phase of backscattered laser pulses traveling in a fiber‐optic cable, and relates this measurement to the axial strain induced on the cable by a propagating seismic wavefield. Combining DAS with telecommunications optical fiber networks has begun to address a range of earth science questions where cost and field logistics have historically hindered observations. Unlike classic inertial seismometers, DAS instrument response is presently unquantified. This topic includes a variable sensing element—the fiber, including packaging and installation—which changes between experiments. Ignoring this element, one DAS record should approximate a fixed‐length strain gauge, which exactly measures Earth's motion down to quasi‐static frequencies relevant to geodesy. In this paper, we test this hypothesis using seismological observations of teleseismic earthquakes and microseism noise spanning the 1 to 120 s period range. We use a commercial DAS interrogator unit connected to an optical fiber previously used for telecommunication and a colocated broadband seismometer to estimate the DAS transfer function. We find a 1:1 correspondence with actual ground motion from 10–120 s. At shorter periods (1–10 s), DAS amplitude response is enhanced by 3–11 dB. Phase response is flat over this range of periods. We interpret the recovered DAS response function in terms of hypothesized fiber coupling and photonic effects. We propose this calibration methodology for future DAS experiments where seismic amplitude information is desired.

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Section: Discussionmentioning

confidence: 77%

Section: The Das Measurement Principlementioning

confidence: 99%

T = 200

s (Yu et al, ). Recently, Becker and Coleman () showed that DAS can record tidal periods (

T = 4.3 \times 1 0^{4}

s) in a laboratory setting, albeit with a strain amplitude

7 \times 1 0^{3}

times greater than the solid Earth tide.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Broadband Instrument Response of Fiber‐Optic DAS Arrays

2020

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“…Using a plane wave decomposition

boldu false(x, t false) = boldU e^{ı false(boldkx - ω t false)}

, we can express the strain component as

ε_{x x} = ı k_{x} u_{x}

, where

boldk

ω

ı

, and

boldx

are the wave number vector, the angular frequency, the imaginary number, and the position, respectively. Since the particle velocity is the time derivative of the displacement (

v_{x} = {\overset{u}{true}}_{x} = \frac{d u_{x}}{d t} = - ı ω u_{x}

), we obtain the relationship linking strain to particle velocity as

ε_{x x} = ı k_{x} u_{x} = - \frac{k_{x}}{ω} {\overset{u}{true}}_{x}

; and as the modes propagate along the surface in the direction

e_{x}

with a phase velocity given by

c = \frac{ω}{k_{x} false(ω false)}

, previous studies (e.g., Wang et al, ; Yu et al, ) used

ε_{x x} = - \frac{1}{c} v_{x}

to compare DAS strain to velocimeter records.…”

Section: Methodsmentioning

confidence: 99%

Urban Seismic Site Characterization by Fiber‐Optic Seismology

et al. 2020

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Accurate ground motion prediction requires detailed site effect assessment, but in urban areas where such assessments are most important, geotechnical surveys are difficult to perform, limiting their availability. Distributed acoustic sensing (DAS) offers an appealing alternative by repurposing existing fiber‐optic cables, normally employed for telecommunication, as an array of seismic sensors. We present a proof‐of‐concept demonstration by using DAS to produce high‐resolution maps of the shallow subsurface with the Stanford DAS array, California. We describe new methods and their assumptions to assess H/V spectral ratio—a technique widely used to estimate the natural frequency of the soil—and to extract Rayleigh wave dispersion curves from ambient seismic field. These measurements are jointly inverted to provide models of shallow seismic velocities and sediment thicknesses above bedrock in central campus. The good agreement with an independent survey validates the methodology and demonstrates the power of DAS for microzonation.

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