TALLINN - Rene Arikas, head of the Estonian Safety Investigation Bureau, restated at the press conference on Tuesday that the wreck of the Estonia ferry has been crushed to a large extent on the starboard side; the analyses of the preliminary survey will take some time and the results will not be delivered until the end of next year.
Arikas said that the objective of the preliminary survey is to assess if there is sufficient basis for launching a safety investigation. No such investigation has been initiated at present and the results of the preliminary survey will determine if such an investigation is necessary.
3D mapping of the seabed revealed that the wreck of the Estonia ferry rests on a slope and that the gradient of the slope is close to 30 meters. There is a protruding outcrop near the middle part of the vessel on which the wreck is resting on its starboard side, which was known already in 1996. The middle area of the vessel rests on moraine and the bow and stern on a layer of soft clay. The soil around the wreck has collapsed on four occasions at different times.
"This means that the soil around the wreck is very unstable and further landslides cannot be ruled out," Arikas said.
Sten Suuroja, head of the department of marine geology and geophysics at the Geological Survey of Estonia, said that the survey was conducted with a boomer system which sends acoustic waves to the bottom of the sea and measures the reflected signal to provide information on sediments and rocks on the seabed.
"The geological composition of the seabed is rather simple in the area of the wreck. It can be seen quite clearly that the middle part of the wreck rests on a hard bedrock," Suuroja said.
"The rock in the middle part of the wreck is so strong it broke our drill," Arikas noted, adding that the clay below the bow and stern definitely offer less support for the wreck.
Arikas noted that the survey focused on damages to the starboard side of the vessel, the bow ramp and the car deck. The vessel's bulbous bow had sustained various damages and scrapes.
"The origin of these damages should be investigated further. With regard to the bow visor, we have conducted theoretical calculations and are planning to carry out a laser scan," Arikas said, adding that the visor is currently located in a military compound in Sweden.
When the bow ramp of the vessel opened in the course of the accident, it came into contact with the protruding bulb at the bow, according to Arikas. When the ship hit the seabed, the ramp closed once more.
"According to our knowledge, the ramp was only slightly open, not fully. The 3D sonar showed, however, that we can see quite far into the wreck on the car deck," he added.
The situation was subsequently surveyed with an underwater robot, which revealed that only a small part of the bow ramp remains attached to a hinge, whereas the ramp itself has fallen to the side of the bow, hence leaving an opening to the car deck. The reason why the ramp has become unattached needs to be investigated further, according to Arikas.
The robot also surveyed the car deck which contained much debris.
"We did not proceed further into the car deck because we had not planned to do so, there was also no direct need for doing so and our equipment would not have enabled it," Arikas said.
Surveys of the deck revealed cracks and outward deformations in the plating of the hull, many of them on the opposite side to the one that hit the seabed.
"Now the extent of the damages going through the hull and the meaning thereof need to be analyzed," Arikas said, adding that survey covered areas of the vessel up to the sixth deck, whereas the seventh and eight decks remained inaccessible.
Surveys of the stern revealed that the stern ramps were closed. A deformation of 22 meters in length and four meters in height was registered in the middle part of the vessel on the starboard side. The plating of the ship has outward deformations as well as in some inward ones and the side fender has been forced inside the vessel.
"Thus, the force that caused this damage had to be enormous," Arikas said, adding that the exact extent of the damage is not known as it could also reach below the hull.
The area of the vessel that has sustained major damages is located next to hard rocks and the deformation matches the geometry thereof, he noted.
A signal that interfered with the sonar was a concern, Arikas said. 3D sonar visibility was 150 meters on the first day of the survey, after which an hour-long interference occurred. Later, the interference was constant, reducing sonar visibility to just 20 meters and preventing the survey crew from measuring the curve of the wreck.
The head of the Safety Investigation Bureau said that the objects near the wreck are also to be identified in the future and a sea current measuring device needs to be retrieved within the next few months to obtain the information recorded by the device.