MID-ATLANTIC RIDGE (12~16oN) BATHYMETRIC ANALYSIS BY EMPIRICAL MODE DECOMPOSITION

The study represents an analysis of bathymetry at and proximal to the Mid-Atlantic Ridge (MAR) between 12°40’~16°15’N, 44.4~45.6°W, where are large bathymetric data set exist in a region where Oceanic Core Complexes have developed. It covers an area of about 15,600 square kilometers that contains at least seven well-documented oceanic core complexes (OCCs) based on previous studies. This study applies 2-D Empirical Mode Decomposition (EMD) to simulate a similar 1D global study of mid-ocean ridges by Small (1994; 1998), but with fewer than 10 intrinsic mode functions (IMFs). With appropriate combination of IMFs, this study acquires not only similar D(x) and S(x), but also can create 2D empirical images from the composition of hundreds of 1-D profiles from a small ridge segment. This is more advantageous because of the higher speeds and because the alternative of using EOF will only allow 1-D profiles, rather to 2-D images. These 2-D images within the small region of the MAR clearly show that certain segments of ridges along MAR have a symmetric system of bathymetric ridges, that the direction of fault scarps is dominantly parallel to the ridge axis, and that they have significant length. The EMD method provides a robust 2-D solution in the analysis of ridge axis bathymetry that may be generally be applicable in understanding the episodic nature of OCC development at slow to intermediate spreading rates, as well as the ultimate causes of symmetric and asymmetric spreading and the distribution of seafloor formed by both processes.