Pradeep N Ranasinghage, University of Ruhuna, Department of Oceanography and Marine Geology, Matara, Sri Lanka, Sachini M Ranasinghe, University of Peradeniya, Peradeniya, Sri Lanka, Konrad A Hughen, WHOI, Woods Hole, MA, United States and Lahiruni Kumari, University of Ruhuna, Matara, Sri Lanka