The Jakarta Post
A geologist has described the two strong earthquakes that hit Lombok, West Nusa Tenggara, on July 29 and Sunday as double-earthquakes or twin earthquakes.
The head of the earthquake and tsunami mitigation division at the Geological Agency, Arifin Joko Pradipto, said what happened in West Nusa Tenggara met the requirements of a so-called double earthquake.
The interval between the two quakes is not too far away, only one week; the quakes’ epicenters were close to each other, or less than 100 kilometers away, and the quakes’ magnitude only showed a little difference.
“But further studies are needed to ensure that they are really double earthquakes,” Joko told The Jakarta Post on Monday in Bandung, West Java.
He said accurate information about the kind of earthquake was important so that the authorities could give the right information to the public.
“In the history of earthquakes in the world, there has been no record of a triple earthquake. If we can confirm that this is a double earthquake, we can safely say to the public that there will not be a bigger earthquake,” Joko said.
The magnitude 7 earthquake hit West Nusa Tenggara, in particular Lombok, on Sunday evening, a week after a 6.4-magnitude earthquake had struck the province. At least 118 people died in both earthquakes and hundreds were injured. The quakes also caused destruction on the three Gili islands.
The head of Volcanology and Geological Hazard Mitigation Center (PVMBG) at the Geological Agency, Kasbani, said the likely double earthquakes were caused by the Flores back arc thrust in a similar subduction zone. The zone spans the northern part of the Lombok and Flores islands in East Nusa Tenggara. “It’s a volcanic arc,” Kasbani added. (vny)
Editor’s note: This article has been corrected to reflect a more accurate quote from the expert. There will NOT be a bigger earthquake.