Transverse Isotropy and the Evolution of the Upper Oceanic Crust

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The concept of apparent thinning of the layer 2A with age due to seismic anisotropy is the central theme of this research. According to the P.I., the horizontal velocity in the upper crust is a much as 40% higher than the velocity measured in the vertical direction. This is due to subhorizontal cracks in the uppermost oceanic crust which are most prominent near the spreading center. With age these cracks are filled by alteration products and this reduces the extent of the anisotropy. In other words, the apparent thinning of layer 2A as observed in seismic reflection and refraction studies is caused by increase in seismic velocities (measured vertically) away from the spreading axis. In this award, the P.I. will test this concept by computer modeling of the existing data and in the process will understand the mechanism of hydrothermal mineralization in the crust. Any such modeling work should be completed before carrying out a field study. The P.I. is a capable theoritical geophysicist and modeler and the study has a very high chance of success.