Bandung, IndonesiaSentinel.com — Soil liquefaction, a phenomenon where the ground moving and loses its structural integrity, arise as a potential threat accompanying megathrust earthquake. A seismic expert from Indonesia’s National Research and Innovation Agency (BRIN) has highlighted that soil liquefaction is one of the potential threats from megathrust earthquakes.
Nuraini Rahma Hanifa, a researcher at BRIN’s Center for Geological Disaster Research, explained that megathrust earthquakes pose both primary and secondary threats. Liquefaction, she noted, is classified as a secondary hazard.
“Liquefaction typically occurs in areas made of sand and saturated with water. When a strong earthquake hits, the saturated sand can lose its structure. This is often seen in coastal regions,” Rahma said.
“Liquefaction makes the soil structure become like mud, and the soil loses its ability to support pressure. If there is a heavy object above, it will sink and collapse,” she added.
Imam Achmad Sadisun, a geology expert from the Bandung Institute of Technology (ITB), explained that liquefaction can be described as the transformation of solid materials, in this case sedimentary deposits or sedimentary soil, whose state can change into a liquid-like state due to an earthquake’s impact.
According to Imam, liquefaction can only occur in water-saturated soils. The water is trapped in the soil’s pores, creating pore water pressure.
“When an earthquake occurs, produces a very strong and sudden tremor, the pore water pressure rises rapidly, sometimes exceeding the frictional strength of the soil. This process is what causes liquefaction to form, making the sand particles in the soil behave as if they’re floating in the water,” Imam explained, in 2018, citing the official ITB website.
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He added that liquefaction typically occurs during earthquakes with a magnitude of 5 or higher, especially when the earthquake source is shallow. The liquefied material is usually found at a depth of around 20 meters, although sometimes it can be more, depending on the soil distribution.
Imam noted that liquefaction only occurs below the local groundwater level and does not occur above it.
In 2018, geologist Rovicky Dwi Putrohari also explained that liquefaction is triggered by seismic vibrations, not by tsunamis. He noted that this phenomenon frequently accompanies earthquake activity.
“Liquefaction occurs because there are earthquake vibrations that trigger coarse fractions (grains) that collect below while finer particles and water are pushed out,” Rovicky said.
Liquefaction is a natural phenomenon caused by seismic activity. This process weakens the soil’s bearing capacity and its ability to hold pressure from above.
“This liquefaction is like tapping a jar to put more items to fit inside. This causes the liquid or fine material to rise to the top,” he concluded.
(Raidi/Agung)
