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

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

Ball, Justin S. (University of Colorado)
Godin, Oleg A. (National Oceanic and Atmospheric Administration)
Evers, L.G. (TU Delft Applied Geophysics and Petrophysics; Royal Netherlands Meteorological Institute (KNMI))
Lv, Cheng (University of Colorado)

2016-08-01

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.

Acoustic properties
Interface waves
Interferometry
Oceanic hotspots and intraplate volcanism
Theoretical seismology
Wave propagation

http://resolver.tudelft.nl/uuid:5bf48b64-e83b-4c94-b7b3-122deeca0e90

https://doi.org/10.1093/gji/ggw110

0956-540X

Geophysical Journal International, 206 (2), 825-834

Institutional Repository

journal article

© 2016 Justin S. Ball, Oleg A. Godin, L.G. Evers, Cheng Lv