Paleaoceanography is actually the study of the history of the oceans in the geologic past with regard to circulation, chemistry, biology, geology and patterns of sedimentation and biological productivity.
The study says that a cave on the Indonesian island of Sumatra, specifically south of Banda Aceh, the capital of Aceh province, is providing a “stunning” record of Indian Ocean tsunamis over thousands of years.
Researchers led by Professor Charles Rubin from the Earth Observatory of Singapore, an institute that forms part of Nanyang Technological University, in collaboration with Indonesian scientists from Syiah Kuala University in Banda Aceh, found inside the cave layers of sandy sediment, which had been washed in by tsunamis thousands of years previously.
The layers, which contained small fossils from the seabed, were well-preserved and separated by droppings deposited by bats in the cave.
“This is a beautiful, stunning record of tsunamis that you just don’t have very often,” Rubin said.
Only huge tsunamis and storm surges can get into the cave, which has a raised entrance — and afterwards the sediment is protected inside from erosion by wind or water.
Rubin said the scientists dated the layers and believe they show that between 2,800 and 3,300 years ago, some four to five tsunamis battered the area.
It will be remembered that a quake-triggered tsunami devastated Aceh and areas across the Indian Ocean in 2004, leaving some 170,000 people dead in the province alone.
Rubin said that the new discovery suggests that tsunamis are not evenly spaced through time, which should provide food for thought for those involved in policy and planning in the region.
“These don’t happen like clockwork, they have variations in time and variations in size,” he said.
“It’s something that communities need to know,” Rubin added.
It is a fitting reminder, especially for those living in the coastal regions, not just in Indonesia, but the Philippines as well, especially that we are now familiar with what a storm surge can bring.