Abstract
Passive seismic interferometry has become very popular in recent years in exploration geophysics. However, it has not been widely applied in marine exploration. The purpose of this study is to investigate the internal structure of a quasi-amagmatic portion of the Southwest Indian Ridge by interferometry and to examine the performance and reliability of interferometry in marine explorations. To reach this goal, continuous vertical component recordings from 43 ocean bottom seismometers were analyzed. The recorded signals from 200 station pairs were cross-correlated in the frequency domain. The Bessel function method was applied to extract phase–velocity dispersion curves from the zero crossings of the cross-correlations. An average of all the dispersion curves was estimated in a period band 1–10 s and inverted through a conditional neighborhood algorithm which led to the final 1D S-wave velocity model of the crust and upper mantle. The obtained S-wave velocity model is in good agreement with previous geological and geophysical studies in the region and also in similar areas. We find an average crustal thickness of 7 km with a shallow layer of low shear velocities and high Vp/Vs ratio. We infer that the uppermost 2 km are highly porous and may be strongly serpentinized.
Highlights
Institut des Sciences de la Terre Paris, Sorbonne Université, CNRS-INSU, ISTeP UMR 7193, Insitut für Geologische Wissenschaften, Freie Universität, 12249 Berlin, Germany; Istituto Nazionale di Geofisica e Vulcanologia, 31, 40100 Bologna, Italy
The considerable quantity of outcrops of serpentinized peridotite on the seafloor is ascribed to exhumation in the footwall of detachment faults known as Oceanic Core Complexes (OCC) [6]
We investigate the robustness of the ambient-noise method in a marine exploration setting
Summary
Institut des Sciences de la Terre Paris, Sorbonne Université, CNRS-INSU, ISTeP UMR 7193, Insitut für Geologische Wissenschaften, Freie Universität, 12249 Berlin, Germany; Istituto Nazionale di Geofisica e Vulcanologia, 31, 40100 Bologna, Italy. Passive seismic interferometry has become very popular in recent years in exploration geophysics It has not been widely applied in marine exploration. Ridge by interferometry and to examine the performance and reliability of interferometry in marine explorations. To reach this goal, continuous vertical component recordings from 43 ocean bottom seismometers were analyzed. The obtained S-wave velocity model is in good agreement with previous geological and geophysical studies in the region and in similar areas. Our study area is located in the easternmost part of the SWIR, centered at 64°350 E and 28°S This easternmost portion of the ridge comprises its deepest parts reaching more than 5500 m below sea level.
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