BANDA ACEH, NETRALNEWS.COM - Researchers from Universitas Syiah Kuala (Unsyiah) in Banda Aceh, Aceh province, have presented evidence of a significantly powerful tsunami that hit Aceh 7,400 years ago in a cave near the coast in Meunasah Lhok, Aceh Besar District.
"Unsyiah research team, in cooperation with Nanyang Technological University (NTU), have conducted research in Lhoong sub district, Aceh Besar," said Unsyiah researcher Nazli Ismail in Darussalam, Banda Aceh.
Nazil explained that the team has identified layers of sand deposited by past tsunami events in the cave where the tsunami sand layers are cross-linked with guano deposits neatly.
According to him, through the process of identifying layers, determining the radioactive age of the carbon element and the analysis of microscopic fossils, scientists have been able to re-couple the events of ancient tsunamis that once struck the land of Aceh.
Nazil mentions that since 7,400 years ago, tsunami incidents in Aceh have been repeated with periods of repetition that varies widely. There are repeated tsunamis in 2000, but there are also recurring events in the span of less than a hundred years.
"The probability of recurrence of massive tsunamis in Aceh is enormous, based on the relationship between the thickness of the tsunami sand layer in the cave and the tsunami recurrence interval, we can conclude that the long period of dormancy is likely to follow the 2004 tsunami," he said.
Nazil continued that the study of the Aceh tsunami cave provides a very important picture of the repetition of tsunami hazards along the subduction zone (Sunda megathrust) stretching to the west off the coast of Sumatra.
According to him, by studying the evidence of ancient tsunamis on the coastal cave, the geologists are increasingly helping to solve the tsunami prediction puzzle similar to the 2004 tsunami in the future.
"During this time, information on the events of ancient tsunamis based on historical records and earthquake equipment recordings is still very short in duration, so the recording is incapable of providing a comprehensive picture of the potential for major tsunamis," Nazli said.
It is therefore necessary to look for larger, longer-term tsunami evidences, both in terms of time and from the repetition side. Such information will be very useful to help reduce disaster risks to the people of Aceh who generally inhabit coastal areas.
Nazli also reminded that one of the concerns that need to be aware of the findings is the evidence of irregularities of massive tsunami resumes that have occurred in Aceh in almost 8000 years.
"This is a big challenge for scientists and governments to save coastal communities from tsunami hazards, and the recording from inside the cave proves that the massive recurrence of tsunami events in Aceh has occurred in a very short span of time and has occurred in the span of 200 years" he added.
Nazil hopes to the government to increase public awareness of tsunami hazard through education. Guha Ek Lenutie in Kecamatan Lhong, Aceh Besar is one of the sites that can be used as a place of learning.
"Unsyiah hopes the existence of the tsunami cave can be preserved, considering that there has been massive stone mining activities around Guha Ek Leuntie in 2016," he said.