Discovered: The cave, which Revealing History of Tsunami in Aceh
A cave was found near the epicenter of the earthquake triggers tsunami in Indonesia, which contains traces of the giant waves of up to 7,500 years ago. A proof of 'natural archives' rare show roughly when the next disaster could happen.
Findings cave on the coast of Aceh shows, that proved there the longest time path and detailed by the tsunamis that have occurred off the coast of the western part of the province of Nanggroe Aceh Darussalam.
Exactly near the epicenter of the earthquake measuring 9.1 on the Richter scale that triggered waves up to 30 meters on December 26, 2004 that killed 230,000 people in a number of countries, half of them in Indonesia.
Limestone cave is located just a few meters off the coast of Banda Aceh, and is one meter above the knee-high waves, as well as protected from storms and winds. Only the large waves that can inundate coastal areas are able to gush into the cave.
Scientists studied the cave mouth. (pict: EOS)
The cave retains the deposits washed ashore by huge waves over thousands of years
Among researchers since 2011 and has found the deposition of sand on the seabed that was swept into the cave thousands of years ago and ends neatly in layers of bat droppings as geological cake.
Radiocarbon analysis on material found, including seashells and the remains of microscopic organisms, gives clear evidence that there are at least 11 tsunami that hit the area before 2004.
The period varies
According to the head of the research team Charles Rubin, a geologist earthquakes (Earthquake Geology) who studied trace tsunami (Paleotsunami) from the Earth Observatory of Singapore (EOS) which is experienced and a lot of researching problems earthquakes worldwide, said that, "Timed shuttle disaster is uncertain ".
Caves in the Aceh tsunami track record (pict:earthobservatory.sg)
The last one before 2004 occurred around 2,800 years ago, but there are four tsunami that occurred in the period of 500 years before that. And there may be other natural disasters.
Researchers know, for example, that there are two major earthquakes in the surrounding region of Banda Aceh around the year 1393 and 1450.
Rubin said that a large tsunami could have been swept evidence of another catastrophe through erosion. But scientists are still trying to determine the size of the waves that can enter the cave.
"The conclusion to be drawn is a major disaster that occurred in 2004 and then it does not mean it will not happen again in the next 500 years," said Rubin, adding that the cave was discovered by accident and not part of the planned field work.
Completing the Data
The earthquake that led to the 2004 tsunami surprised many among researchers, because the fault that produced a devastating earthquake, it is not active in hundreds of years.
And since a massive earthquake last more than 500 years earlier, there was never any oral history can help understand such risks.
Since 2004, many studies were conducted to try to understand the history of the western coast of the island of Sumatra by examining the pile of sand, raised coral and GPS data.
GPR survey in the cave, Aceh, Indonesia (pict: EOS)
"The findings are very significant," said Katrin Monecke, a professor of earth sciences diWellesley College in Massachusetts, USA.
He studied the pile of sand tsunami found in marshes in the region, but is not involved in the research of the cave, which was presented at the American Geophysical Union conference in San Francisco.
Charles Rubin also explained, "Layers of sand inside the cave record in a very long period of time and provide information on the frequency of the earthquake," says Rubin, head of the research team.
Although the long-term recordings are protected in the cave, Rubin said the frequency of tsunamis still can not be known exactly or roughly when a catastrophe could occur in the short period between each other.
The Aceh tsunami record from about 7,500 to 3,000 years ago is impeccable (pict: EOS)
Perspective geophysicist
Geologist Kerry Sieh, director of EOS is also involved in a cave, has predicted that the giant earthquake rocked Aceh can return in the coming decades.
Giant earthquakes generally come in the form of a cycle, and the earthquake in 2004 and then increase more pressure on the fracture earlier. But its history is very diverse, making it impossible to give very precise predictions.
Charles Rubin with this reseach team's efforts focus on earthquake processes and active tectonics.
The team is currently working on a comprehensive study of the great earthquakes
along the Sunda megathrust using paleoseismic techniques. (pict: EOS)
"By studying the types of tsunamis in the past, maybe we can plan mitigation for the next tsunami," said Nazli Ismail, head of the department of physics and geophysics at the University of Syiah Kuala in Banda Aceh, who worked on this project.
The Indonesian archipelago sits on the Ring of Fire (Ring od Fire) dipinggiran Pacific Ocean, which is a chain of volcanoes that have a fault line, which surrounds hanpir entire Pacific Ocean basin. This is where a lot of seismic activity occurs biggest and the deadliest in the world!
