What is a Megathrust Earthquake That is Said to Occur in Indonesia

TEMPO.CO, Jakarta - News about the megathrust earthquake has been circulated due to the daunting warning that the Meteorology, Climatology, and Geophysics Agency (BMKG) released a few while back.

According to the Head of BMKG, Daryono, the megathrust potential has been a recurring topic as of Tempo's report on August 15th.

Daryono clarified that the alarming warning is to remind the existence of the Sunda Strait and Mentawai-Siberut Megathrust Zone that has been latent for over hundreds of years resulting in a potential seismic event.

While the BMKG will broadcast accurate recent news regarding the seismic activities, understanding megathrust earthquakes is advisable to make advances on later days. This article will explore the definition of megathrust earthquake and its prominent danger, cited from nature.com and Eos.org.

What is a Megathrust Earthquake?

Megathrust earthquake is by far the most powerful earthquake in the world occurring in subduction zones as a result of a decisive wham between two intersected tectonic plates. The neverending thrust of the involved plates is an enormous rupture, demonstrating a great stress in the area where the oceanic plates are bound together. The megathrust earthquake takes place due to the build up strain.

The recurrence time of a megathrust earthquake heavily varies from one subduction zone to another. For instance, as many as 13 megathrust activities occurred in the Cascadia subduction zone for the last 6000 years with all of which have not emerged regularly. The interval ranges from 200 years to 800 years apart.

As Tempo reported, the last major earthquake in the Sunda Strait took place in 1757 with a seismic gap of 267 years. Meanwhile the most recent major earthquake in Mentawai-Siberut emerged in 1797 with a seismic gap of 227 years.

Detailed measurements on the seismic event are challenged due to the sources of the megathrust earthquake being normally situated deep under the sea. However, the knowledge about megathrust earthquakes has seen more advancement in many aspects as quoted from Eos.org.

How Dangerous a Megathrust Earthquake is?

Megathrust earthquakes are often feared to generate tsunami in many oceanic plate areas including in the Sunda Strait, Mentawai-Siberut and Japan. Matter of fact, the danger of a megathrust earthquake is said to be both catastrophic earthquake and a tsunami.

Four most popular tsunamis occurred respectively in Sumatra 2004, Japan 2011, Chile 2010, and Alaska 2013 are stemmed by subduction zone megathrust earthquakes.

The massive and incessant thrusting motion of a megathrust earthquake generates a huge movement underneath the sea, resulting in an immeasurable water volume being disclosed directly from the sea floor. The occurrence is wildly informed as a tsunami. Citing from an earthscope consortium paper, tsunamis consist of multiple waves that arrive many hours after the initial wave is identified on the shore.

The danger of a disruptive earthquake is also to be expelled from a megathrust earthquake. Daryono added, currently there is no science based technology that is able to accurately predict earthquakes in terms of time, location and strength. Therefore, it is important to seek knowledge about a megathrust mitigation.

Editor's Choice: BMKG Clarifies on Megathrust Earthquake Warning in Indonesia

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