Earthquake Lasting for 20 Seconds or More May Indicate Potential Tsunami

TEMPO.CO, Bandung - Researchers could not precisely identify which type of earthquake that would trigger a tsunami, said Abdul Muhari as the acting head of the disaster risk mapping and evaluation at the National Disaster Mitigation Agency (BNPB). 

“Every tsunami is unique. The characteristics after a quake are not the same,” said Muhari on Thursday, October 1, 2020.

Muhari, who is also a member of the research team of potential major quakes and tsunamis in South Java led by the Bandung Institute of Technology (ITB) researchers, recalled that back in 2007, Mentawai Island was rocked by a powerful quake with a magnitude of 8.6.

“The shaking was so strong but followed with a very small tsunami,” he said on Thursday, October 1, 2020.

Meanwhile, on October 25, 2010, the island was struck by a strong quake too at a 7.2 magnitude which lasted about 30 seconds. Yet it was followed by a tsunami as high as 1 to 15 meters that hit the Pagai-Mentawai Islands areas.

The BNPB noted that the disaster killed more than 400 people and 15,000 people were evacuated. “The quake was weak, but suddenly eight minutes later a 12-15-meter tsunami hit the island,” said Muhari.

However, Muhari reiterated that there was a factor that could be considered as a guide for the public to prepare for a tsunami, especially those living in coastal areas. He said a quake that is followed by a tsunami usually releases energy for a long time.

“If there is a weak or strong earthquake and the shaking continues for more than 20 seconds, it is the right time to start the evacuation,” Muhari concluded.

Read: 15 Years On; Behind the Catastrophic Aceh Tsunami and Earthquake

ANWAR SISWADI