Justin S. Ball

University of Colorado Boulder

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A. F. Sheehan

University of Colorado Boulder

J. A. Collins

Woods Hole Oceanographic Institution

Fan‐Chi Lin

University of Utah

Oleg A. Godin

Naval Postgraduate School

Joshua C. Stachnik

Lehigh University

J. C. Stachnik

Lehigh University

Liudmila Zabotina

University of Colorado Boulder

William L. Yeck

United States Geological Survey

Michael G. Brown

Iowa State University

N. A. Zabotin

University of Colorado Boulder

Cooperative Institutions

University of Colorado Boulder

Cooperative Institute for Research in Environmental Sciences

University of Colorado System

GNS Science

University of Miami

The University of Texas at Austin

United States Geological Survey

Crown Research Institutes

Lamont-Doherty Earth Observatory

University of California, Santa Cruz

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Ocean acoustic remote sensing using ambient noise: results from the Florida Straits

Geophysical Journal International (2016)

Michael G. Brown Oleg A. Godin Xiaoqin Zang Justin S. Ball N. A. Zabotin

Noise interferometry is the process by which approximations to acoustic Green's functions, which describe sound propagation between two locations, are estimated by cross-correlating time series of ambient noise measured at those locations. Noise-interferometry-based approximations to Green's functions can be used as the basis for a variety of inversion algorithms, thereby providing a purely passive alternative to active-source ocean acoustic remote sensing. In this paper we give an overview of results from noise interferometry experiments conducted in the Florida Straits at 100 m depth in December 2012, and at 600 m depth in September/October 2013. Under good conditions for noise interferometry, estimates of cross-correlation functions are shown to allow one to perform advanced phase-coherent signal processing techniques to perform waveform inversions, estimate currents by exploiting non-reciprocity, perform time-reversal/back-propagation calculations and investigate modal dispersion using time-warping techniques. Conditions which are favourable for noise interferometry are identified and discussed.

Ambient noise level

Seismic interferometry

Cross-correlation

10.1093/gji/ggw170

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Citations (18)

Long-range correlations of microseism-band pressure fluctuations in the ocean

Geophysical Journal International (2016)

Justin S. Ball Oleg A. Godin L. G. Evers Cheng Xing Lv

We investigate the spatial coherence of underwater ambient noise using a yearlong time-series measured off Ascension Island.Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area.In particular, the model correctly predicts the existence of two weakly dispersive normal modes in the microseism frequency range, with the group speed of one of the normal modes being smaller than the sound speed in water.The agreement justifies our interpretation of the peaks of the measured cross-correlation function of ambient noise as modal arrivals, with dispersion that is sensitive to crustal velocity structure.Our observations are consistent with Scholte to Moho head wave coupled propagation, with double mode conversion occurring due to the bathymetric variations between receivers.We thus demonstrate the feasibility of interrogating crustal properties using noise interferometry of moored hydrophone data at ranges in excess of 120 km.

Microseism

10.1093/gji/ggw110

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Citations (7)

Teleseismic P-Wave Coda Autocorrelation Imaging of Crustal and Basin Structure, Bighorn Mountains Region, Wyoming, U.S.A.

Bulletin of the Seismological Society of America (2020)

S. M. Plescia A. F. Sheehan Seth S. Haines L. L. Worthington Scott Cook

ABSTRACT We demonstrate successful crustal imaging via teleseismic P-wave coda autocorrelation, using data recorded on a 261 station array of vertical-component high-frequency geophones in the area of the Bighorn Mountains, Wyoming, U.S.A. We autocorrelate the P-wave coda of 30 teleseismic events and use phase-weighted stacking to yield seismic profiles comparable to low-passed versions of those produced via controlled-source vertical seismic reflection. Our process recovers reflections from the bottoms of the Bighorn and Powder River basins that flank the Bighorn Mountains. We also identify a mid-crustal reflector that aligns with a region of increased reflectivity, previously interpreted as a Precambrian province boundary. Our results demonstrate the utility of crustal imaging with teleseismic P-wave coda energy using modern large-array seismic data, and they corroborate previous interpretations of crustal structures in the study area.

Coda

Geophone

Reflector (photography)

Reflection

10.1785/0120200177

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Citations (8)

Long-range correlations of microseism-band pressure fluctuations in the ocean

The Journal of the Acoustical Society of America (2017)

Justin S. Ball Oleg A. Godin L. G. Evers Cheng Xing Lv

We investigate the spatial coherence of underwater infrasonic noise using a yearlong time series measured by hydrophones moored off Ascension Island. Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area. In particular, the model correctly predicts the existence of two weakly dispersive normal modes in the microseism frequency range, with the group speed of one of the normal modes being smaller than the sound speed in water. The agreement justifies our interpretation of the peaks of the measured cross-correlation function of ambient noise as modal arrivals, with dispersion that is sensitive to crustal velocity structure. Our observations are consistent with Scholte to Moho head wave coupled propagation, with double mode conversion occurring due to the bathymetric variations between receivers. We thus demonstrate the feasibility of interrogating crustal properties using noise interferometry of moored hydrophone data at ranges in excess of 120 km.

Microseism

Hydrophone

Ambient noise level

Seismic interferometry

10.1121/1.4989356

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Citations (0)

Lithospheric Shear Velocity Structure of South Island, New Zealand from Rayleigh Wave Tomography of Amphibious Array Data

Justin S. Ball A. F. Sheehan J. C. Stachnik Fan‐Chi Lin J. A. Collins

Rayleigh Wave

Seismic Tomography

Wave velocity

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Passive seismoacoustic imaging from the seafloor to the lithosphere: Methods and applications to New Zealand and Ascension Island

Justin S. Ball

Seafloor Spreading

Source

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Lithospheric shear velocity structure of South Island, New Zealand, from amphibious Rayleigh wave tomography

Journal of Geophysical Research Solid Earth (2016)

Justin S. Ball A. F. Sheehan Joshua C. Stachnik Fan‐Chi Lin William L. Yeck

Abstract We present a crust and mantle 3‐D shear velocity model extending well offshore of New Zealand's South Island, imaging the lithosphere beneath the South Island as well as the Campbell and Challenger Plateaus. Our model is constructed via linearized inversion of both teleseismic (18–70 s period) and ambient noise‐based (8–25 s period) Rayleigh wave dispersion measurements. We augment an array of 4 land‐based and 29 ocean bottom instruments deployed off the South Island's east and west coasts in 2009–2010 by the Marine Observations of Anisotropy Near Aotearoa experiment with 28 land‐based seismometers from New Zealand's permanent GeoNet array. Major features of our shear wave velocity ( V s ) model include a low‐velocity ( V s < 4.4 km/s) body extending from near surface to greater than 75 km depth beneath the Banks and Otago Peninsulas and high‐velocity ( V s ~4.7 km/s) mantle anomalies underlying the Southern Alps and off the northwest coast of the South Island. Using the 4.5 km/s contour as a proxy for the lithosphere‐asthenosphere boundary, our model suggests that the lithospheric thickness of Challenger Plateau and central South Island is substantially greater than that of the inner Campbell Plateau. The high‐velocity anomaly we resolve at subcrustal depths (>50 km) beneath the central South Island exhibits strong spatial correlation with upper mantle earthquake hypocenters beneath the Alpine Fault. The ~400 km long low‐velocity zone we image beneath eastern South Island and the inner Bounty Trough underlies Cenozoic volcanics and the locations of mantle‐derived helium measurements, consistent with asthenospheric upwelling in the region.

Asthenosphere

Rayleigh Wave

Seismic Tomography

Low-velocity zone

Shear velocity

10.1002/2015jb012726

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Citations (21)

Rayleigh wave ambient noise tomography from an amphibious array of seismic stations, South Island, New Zealand

AGUFM (2012)

J. C. Stachnik A. F. Sheehan Justin S. Ball J. A. Collins

Ambient noise level

Rayleigh Wave

Seismic Noise

Seismic Tomography

Source

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A Joint Monte Carlo Inversion of Seafloor Compliance, Receiver Functions and Rayleigh Wave Dispersion at OBS Stations off New Zealand

AGU Fall Meeting Abstracts (2012)

Justin S. Ball A. F. Sheehan J. C. Stachnik J. A. Collins

Seafloor Spreading

Source

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Hydroacoustic signals of Antarctic origin detected at ocean-bottom seismic stations off New Zealand

The Journal of the Acoustical Society of America (2014)

Justin S. Ball A. F. Sheehan

Glacial calving from polar ice sheets is an important indicator of global climate change, and knowledge of ice discharge rates is useful for predicting global sea level variability and deep ocean circulation patterns. Since calving events are difficult to observe in-situ due to the remoteness of polar regions, the remote detection of hydroacoustic signals originating from these events is a useful monitoring tool for climatologists. We have observed hydroacoustic T-phases on an Ocean Bottom Seismic (OBS) network of 30 seismometers and differential pressure gauges that was deployed off the South Island of New Zealand in 2009–2010. These signals are emergent and strongly dispersive, containing most of their energy in the band between 5 and 15 Hz. We estimated backazimuths for events recorded on differential pressure gauges using array beamforming and F-K analysis. Our results suggest that some observed events originate in the vicinity of Ninnis and Mertz glaciers on George V Coast, East Antarctica, in general agreement with epicenters located by prior surface-wave based calving detection studies.

Seismometer

10.1121/1.4877605

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