First results of the geological-geomorphological investigations
During March and April 2002, a group of maps of the seafloor northwest of Guanahacabibes Peninsula were prepared. They are as follows: Slope Map, 3D Digital Relief Map, Tectonic Map and a Morphostructural Map.
The detailed bathymetry shows the disposition of the steep slopes which are strongly related to fractures and active faults.
The main structure of the area follow the trend of a series of marine escarpments with different directions.
The tectonic map reveals N-E and N-S trending, in a lesser degree E-W trending fractures and active faults. Due to these faults a network of blocks of different sizes and altitude can be defined. There are horst (positive) blocks, rising at shallow depths (positive landscape) as the Shoal of San Antonio and the insular platform of Cuba (green). Others blocks are located at intermediate altitude, but at two main levels (light and dark orange). The deep seated blocks (grabens) are located up to 1 500 meters below sea level (dark blue).
The 3D digital map (above) shows MEGA lying on a relatively depressed block; however, it is sitting close to the highest structures in the area. This might suggest that the block on which MEGA is located had been emerged above sea level in the past. A morphostructural study was undertaken in order to assess this matter in detail.
The figure above show the main morphostructures of the sea bottom near MEGA. Notice the curved features (amphitheatre) related to submarine slumping, associated to fractures, faults and steeps slopes. The side scan sonar images below are examples of these features.
The following submarine photographs illustrate the sea bottom above one scarp (left) and the scarp wall (right). The rocks on the walls and those located at the base of the scarps are of dark color, irregular in shape, while the megaliths are white and usually geometrically shaped.
The 3D digital map (below) shows the position of the collapse structures along the faults, as well as the location of the megaliths on a slightly inclined structural depression. Thus, this report concludes that the megalithic structures are not associated with faults, fractures or breaks on the slope. Therefore, its origin is yet to be understood.
. 
YELLOW ARROWS: submarine landslide, BLACK ARROWS: bottom channels, BROWN LINES: faults
