Padangekspres.net-Two strong earthquakes that hit Aceh on Wednesday, April 11, of 8.5 and 8.1 on the Richter scale respectively, have become a valuable lesson and a reminder that earthquakes can hit the nation at any time.
Experts have warned Jakarta that there are 12 earthquake sources surrounding the Indonesia's capital.
The Encyclopedia of World Geography illustrates that Batavia, the old Jakarta, was once destroyed by earthquake in 1699, causing landslides to hit Liwung (Ciliwung) River. Large quantities of mud and trees that fell to the river triggered flood and clogged the canals in Oud Batavia, Old Jakarta.
The paper "Historical Evidence for Major Tsunamis in the Java Subduction Zone" of the Asia Research Institute has also depicted matters on the earthquake. On January 5, 1699, Batavia was shaken by an unimaginable earthquake like never before.
At that time, the quake happened for 45 minutes to 1 hour and recurred on the following days. A report said 28 people were killed, 49 buildings collapsed and almost all houses were damaged.
However, the cause of the quake remains unrecognized. Assumption has it that the epicenter was in the south of Batavia. However, the quake was also believed to have been in line with the eruption of Mount Salak, West Java.
A lecturer of Geophysics & Meteorology of Bandung Institute of Technology (ITB), who is also a member of Team 9 of Earthquake Mapping, Wahyu Triyoso, said around 200 years after the 1699’s earthquake, Jakarta was hit by a similar earthquake on 27 Fenruary 1903.
“The urgent thing is actually to find out the correlation between the quakes in 1699 and 1903,” he told VIVAnews on Wednesday. Should the premise prove right, a chance for recurring earthquakes in every 200 years is possible.
The earthquake in 1903, he said, was a result of an activation of strike-slip faults, which was similar to what had happened in Aceh on 11 April 2012.
Wahyu claimed earthquake signature can be identified through historical data. “Researchers can collect fault data then prepare a reconstruction by applying some model. Through a simulation, the estimate location of strain energy accumulation will be discovered.” He said.
The fact that the cause of Jakarta’s quake is still unknown was mentioned once by a Presidential advisor on Social & Disaster Assisstance, Andi Arief. “Our historical records and research reports only mention [eartqhuake sources] to Sunda Strait and Lembang Fault. Jakarta was once destroyed in 1699 obviously, but we can't figure the source out yet,” he said.
At the moment, he said, seismic experts are tracking down the cycle of strong earthquakes in several regions of Indonesia. According to the experts, recurring earthquakes are due in almost all regions starting from Meulaboh, West Sumatra, Bengkulu, Lampung, to the eastern parts of Indonesia.
“The last time occurred by the end of 1900. Then it ceased for another 100 years. The last one was in 1903 then recurred in 2004. It’s a cycle of 100-250 years. We suspect there is a cycle of hundreds of years. We speculate that the cycle in Aceh happens once in every 600 years,” he said.
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