Disaster Preparedness: What to Do When Megathrust Earthquake Strikes

TEMPO.CO, Jakarta - The Meteorology, Climatology, and Geophysics Agency (BMKG) revealed that major earthquakes could potentially occur in the Sunda Strait and Mentawai-Siberut megathrust zones. According to BMKG, the megathrust zones created a seismic gap, or the absence of major earthquakes for hundreds of years.

Citing Antara, the Sunda Strait megathrust seismic gap could reach 8.7 magnitudes, and the Mentawai-Siberut megathrust earthquake could reach 8.9 magnitudes. 

Although BMKG cannot confirm when the megathrust will occur, the possibility of a major earthquake was widely discussed by the Indonesian public. Especially after the earthquake in Yogyakarta on Monday, August 26, 2024.

Earthquakes are destructive disasters, especially those with large magnitudes. Earthquakes come suddenly, so it’s understandable that people without a proper understanding of disaster mitigation will panic and feel anxious.  

For those living in coastal areas, fear of tsunamis also loom alongside earthquakes. Additionally, megathrust earthquakes could trigger tsunamis. So, what do we do when an earthquake strikes? Here’s the explanation.

What to do during megathrust earthquakes

When facing a megathrust earthquake, the first thing to remember is to condition ourselves to remain calm and not panic. Panic will obstruct our ability to remain clear-headed, and quick decision-making is necessary when you find yourself in an earthquake. 

If you are at home, go outside and find a place far from buildings, trees, and other objects at risk of falling or collapsing. 

Especially for coastal communities, immediately head to higher ground in case of a megathrust earthquake. When an earthquake occurs, seawater could rise higher, and in some cases trigger a tsunami potential. 

Make sure you can identify the signs of an incoming tsunami. The visible characteristics when a tsunami is about to occur are receding coastal waters. When that happens, immediately run from coastal areas, since it’s highly possible seawater will soon hit the land. 

When a megathrust earthquake occurs at night, electricity and telecommunications lines will likely be cut off. If this happens, immediately look for a multi-story building and go upstairs. The coastal area is the first to be affected by a megathrust event that is followed by rising ocean waves. When the surrounding environment has been flooded with water, be aware of the environment around you. 

The government has installed early warning devices for tsunamis. If an earthquake occurs and triggers the tsunami potential, sirens will blare. Run from the coast and head to higher grounds immediately after you hear the warning sirens.

Megathrust zones in Indonesia

A megathrust earthquake originates from the megathrust zone which has existed for millions of years. Megathrust zone is a term used to describe the meeting points between the earth's tectonic plates that could trigger major earthquakes and tsunamis.

Indonesia's megathrust zones are located in active subduction zones, such as the Sunda subduction. The Sunda subduction zone includes Sumatra, Java, Bali, Lombok, and Sumba. 

There are other active subduction zones in Indonesia, namely the Banda subduction, the Maluku Sea plate subduction, the Sulawesi subduction, the Philippine Sea plate subduction, and the North Papua subduction. This active subduction zone in Indonesia is divided into several segments of the megathrust zones. 

TIARA JUWITA | EIBEN HEIZER | RACHEL FARAHDIBA REGAR

Editor’s Choice: Indonesian Regions with Megathrust Zones; Beware of Earthquakes and Tsunamis - Sci En.tempo.co. 

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