Correction of OBS clock errors using Scholte waves retrieved from cross-correlating hydrophone recordings

Le, Ba Manh; Yang, Ting; Chen, Yongshun John; Yao, Huajian

doi:10.1093/gji/ggx449

Cited by 34 publications

(22 citation statements)

References 23 publications

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“…The timing of an OBS recording depends on its own internal clock, which is only synchronized with GPS before deployment and after recovery. Large timing error might arise from glitches with the clock or data logger (Le et al 2018). Therefore, we corrected timing errors of each OBS prior to locating earthquakes.…”

Section: Inspection Of Obs Timing From Teleseismic Earthquakesmentioning

confidence: 99%

“…To accurately estimate the timing shift of OBSs, we then adopted time symmetry analysis using ambient noise cross-correlation functions (NCCF, Stehly et al 2007;Gouédard et al 2014;Le et al 2018). Cross-correlation of a diffuse field yields empirical Green's functions of the medium between two receivers (Shapiro et al 2005 (Kato et al 2003).…”

Section: Obs Timing Correction Using Ambient Noise Cross-correlationmentioning

confidence: 99%

“…We preferentially used the hydrophone recordings because they provided higher signal-to-noise ratio (SNR) in NCCF than seismometers (Le et al 2018). Since the hydrophone at PA09 station was not functional, we used the vertical component of PA09 OBS to calculate the NCCF with other vertical components.…”

Section: Obs Timing Correction Using Ambient Noise Cross-correlationmentioning

confidence: 99%

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Along-strike variation in slab geometry at the southern Mariana subduction zone revealed by seismicity through ocean bottom seismic experiments

Zhu

Yang

Lin

et al. 2019

Geophysical Journal International

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SUMMARYWe have conducted the first passive Ocean Bottom Seismograph (OBS) experiment near the Challenger Deep at the southernmost Mariana subduction zone by deploying and recovering an array of 6 broad-band OBSs during December 2016–June 2017. The obtained passive-source seismic records provide the first-ever near-field seismic observations in the southernmost Mariana subduction zone. We first correct clock errors of the OBS recordings based on both teleseismic waveforms and ambient noise cross-correlation. We then perform matched filter earthquake detection using 53 template events in the catalogue of the US Geological Survey and find >7000 local earthquakes during the 6-month OBS deployment period. Results of the two independent approaches show that the maximum clock drifting was ∼2 s on one instrument (OBS PA01), while the rest of OBS waveforms had negligible time drifting. After timing correction, we locate the detected earthquakes using a newly refined local velocity model that was derived from a companion active source experiment in the same region. In total, 2004 earthquakes are located with relatively high resolution. Furthermore, we calibrate the magnitudes of the detected earthquakes by measuring the relative amplitudes to their nearest relocated templates on all OBSs and acquire a high-resolution local earthquake catalogue. The magnitudes of earthquakes in our new catalogue range from 1.1 to 5.6. The earthquakes span over the Southwest Mariana rift, the megathrust interface, forearc and outer-rise regions. While most earthquakes are shallow, depths of the slab earthquakes increase from ∼100 to ∼240 km from west to east towards Guam. We also delineate the subducting interface from seismicity distribution and find an increasing trend in dip angles from west to east. The observed along-strike variation in slab dip angles and its downdip extents provide new constraints on geodynamic processes of the southernmost Mariana subduction zone.

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Section: Inspection Of Obs Timing From Teleseismic Earthquakesmentioning

confidence: 99%

Section: Obs Timing Correction Using Ambient Noise Cross-correlationmentioning

confidence: 99%

Section: Obs Timing Correction Using Ambient Noise Cross-correlationmentioning

confidence: 99%

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Along-strike variation in slab geometry at the southern Mariana subduction zone revealed by seismicity through ocean bottom seismic experiments

Zhu

Yang

Lin

et al. 2019

Geophysical Journal International

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“…Seventeen stations were successfully recovered, with 11 recording valid data. Most of the recovered OBSs have data for 7–8 months, but three OBSs recorded only ∼3 months of data due to various issues with the instrumentation (Le et al., 2018; Liu et al., 2014).…”

Section: Data and Rfmentioning

confidence: 99%

Crustal Structure Across the Extinct Mid‐Ocean Ridge in South China Sea From OBS Receiver Functions: Insights Into the Spreading Rate and Magma Supply Prior to the Ridge Cessation

Hung

Yang

et al. 2021

Geophysical Research Letters

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The crust near an extinct mid‐ocean ridge provides unique constraints on how its accretion and deformation responded to the cessation of spreading. Here we present crustal thickness and Vp/Vs measurements beneath 11 Ocean Bottom Seismograph sites that cross the South China Sea's extinct spreading axis. We find that the oceanic crust, which generally had only slight thickness changes once spreading started, abruptly thins at sites close to the extinct ridge axis. Abnormally high Vp/Vs ratios are obtained at several sites south of the ridge, indicating the presence of serpentine. These observations imply that, in its final stage, spreading changed to an ultraslow accretion style. As the axial crust thinned, normal faults and/or detachment faults began to form. Water could penetrate more deeply through these faults, and large fault slip could raise ultramafic peridotites to near or at the seafloor, creating favorable conditions for their enhanced serpentinization.

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“…Similarly, regional ocean bottom networks, often deployed for the purpose of tomographic imaging, may suffer from clock drift of constituent ocean bottom seismometers (OBSs) (e.g. Gouédard et al 2014;Takeo et al 2014;Hable et al 2018;Le et al 2018). In this case, the timing errors may result in erroneous seismic images and hence false geological interpretations.…”

Section: Introductionmentioning

confidence: 99%

Systematic recovery of instrumental timing and phase errors using interferometric surface-waves retrieved from large-N seismic arrays

Weemstra

Laat

Verdel

et al. 2020

Geophysical Journal International

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Summary Instrumental timing and phase errors are a notorious problem in seismic data acquisition and processing. These can be frequency independent, for example due to clock drift, but may also be frequency dependent, for example due to imperfectly known instrument responses. A technique is presented that allows both types of errors to be recovered in a systematic fashion. The methodology relies on the time-symmetry usually inherent in time-averaged crosscorrelations of ambient seismic noise: the difference between the arrival time of the direct surface wave at positive time and the arrival time of the direct surface wave at negative time is quantified. Doing this for all eligible receiver-receiver pairs of a large-N seismic array, including one or more receivers devoid of instrumental timing errors, the instrumental timing errors of all incorrectly timed receivers can be determined uniquely. Most notably, this is accomplished by means of a weighted least-squares inversion. The weights are based on the receiver-receiver distances and decrease the adverse effect of inhomogeneities in the noise illumination pattern on the recovered instrumental timing errors. Inversion results are furthermore optimized by limiting the inversion to receiver couples that (i) exceed a specific receiver-receiver distance threshold and (ii) whose time-averaged crosscorrelations exceed a specific signal-to-noise ratio threshold. Potential frequency dependence of the timing errors is incorporated by means of an iterative, frequency-dependent approach. The proposed methodology is validated using synthetic recordings of ambient seismic surface-wave noise due to an arbitrary non-uniform illumination pattern. The methodology is successfully applied to time-averaged crosscorrelations of field recordings of ambient seismic noise on and around the Reykjanes peninsula, SW Iceland.

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Correction of OBS clock errors using Scholte waves retrieved from cross-correlating hydrophone recordings

Cited by 34 publications

References 23 publications

Along-strike variation in slab geometry at the southern Mariana subduction zone revealed by seismicity through ocean bottom seismic experiments

Along-strike variation in slab geometry at the southern Mariana subduction zone revealed by seismicity through ocean bottom seismic experiments

Crustal Structure Across the Extinct Mid‐Ocean Ridge in South China Sea From OBS Receiver Functions: Insights Into the Spreading Rate and Magma Supply Prior to the Ridge Cessation

Systematic recovery of instrumental timing and phase errors using interferometric surface-waves retrieved from large-N seismic arrays

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