Megathrust Zone Identified as Pagai Earthquake`s Epicenter

TEMPO.CO, Bandung - The tectonic earthquake that struck the island of Pagai and its immediate surrounds on Wednesday night, August 24, 2016, originated from a megathrust zone - where the Indo-Australian plate subducts beneath the Eurasian plate at a relatively shallow depth right below Pagai Island, in the Mentawai Islands Regency in West Sumatra.

The earthquake, which measures at 5.6 on the Richter Scale (SR), triggered no tsunami warning.

The Head of Earthquake and Tsunami Mitigation for the Meteorology, Climatology, and Geophysics Agency, issued a statement that the earthquake struck at 20:48 Western Indonesia Time (WIB) - the epicentre of the earthquake is located around 6 kilometres west of the Malakopa District on South Pagai Island, at a depth of 25 kilometres.

According to BMKG's 'shake map' analysis, the vibrations could be felt across Malakopa, Muntai, Siberut, Sikakap, Mukomuko, Solok, Painan, and Padang - measuring at II or III on the Modified Mercalli Scale (MMI).

This shallow earthquake at a megathrust zone occurred due to a phenomenon known as thrust fault - wherein a tectonic plate that pushes a subducting plate below it suddenly cracks upwards. A major thrust fault could indeed cause a tsunami.

Many residents reportedly panicked and scrambled their way out of their homes due to the earthquake, which seemed to occur without any warning - but as of Wednesday evening, no immediate reports of damages have been made public.

Although panic had set after the initial vibrations from the quake was felt, lives quickly came back to normal as inhabitants of North and South Pagai have been relocated to higher grounds that will provide adequate protection from any potential tsunami.

ANWAR SISWADI