Imagine standing on solid ground, only to have it suddenly behave like water—swallowing buildings, roads, and lives in mere moments. This isn't a scene from a science fiction movie; it's the terrifying reality of soil liquefaction, a phenomenon that has repeatedly devastated parts of Southeast Asia. Yet, despite its catastrophic potential, many remain unaware of its dangers. Let's delve into this silent threat lurking beneath our feet.
What Is Soil Liquefaction?
Soil liquefaction occurs when saturated, loose soils lose their strength and stiffness in response to stress, such as seismic shaking, causing them to behave like a liquid. This process undermines the foundations of structures, leading to catastrophic failures.
Dr. Stavroula Kontoe of Imperial College London explains, “When soil is saturated, the space between individual particles is completely filled with water. Seismic shaking increases the water pressure between the soil particles; the particles can lose contact with each other, which in turn leads to an overall loss of soil strength and stiffness,” as quoted from The Guardian.
Read also: 5 Largest Earthquakes Ever Recorded in Southeast Asia
The 2018 Palu Disaster: A Case Study
On September 28th, 2018, a 7.5 magnitude earthquake struck Central Sulawesi, Indonesia, triggering a tsunami and widespread soil liquefaction. Entire neighborhoods, such as Petobo and Balaroa, were engulfed as the ground turned to mud, swallowing homes and lives. The death toll exceeded 4.000, making it one of the deadliest disasters in Indonesia's history.
Eyewitness Susanti recounted, “Houses were tumbling. They started to roll like waves. It’s like a tsunami, but the difference was they were waves of soil.”
Why Southeast Asia Is Particularly Vulnerable
Several factors contribute to the region's susceptibility:
- Geological Setting: Southeast Asia lies along the Pacific Ring of Fire, making it prone to frequent and intense seismic activity.
- Soil Composition: Many areas have loose, sandy soils with high water tables, ideal conditions for liquefaction.
- Rapid Urbanization: Unplanned development often overlooks geotechnical assessments, placing structures in high-risk zones.
Dr. Kyle Bradley from Nanyang Technological University warns, “This event is a wake-up call for any area where active faults and irrigation coincide. We need to improve the awareness and understanding of liquefaction-related landslides.”
The Human Cost: Beyond the Numbers
Beyond the staggering death tolls, liquefaction leaves lasting scars:
- Displacement: Entire communities are uprooted, with survivors often relocated to unfamiliar areas.
- Economic Impact: Destruction of infrastructure hampers local economies, sometimes for years.
- Psychological Trauma: The sudden and unpredictable nature of liquefaction-induced disasters leaves deep emotional wounds.
As survivor Erli Yati expressed, “I will not step back to that place again. That was the worst experience I have ever had.”
Mitigation and Preparedness: Steps Forward
Addressing the threat requires a multifaceted approach:
- Risk Mapping: Identifying and publicizing high-risk zones to inform development decisions.
- Building Codes: Implementing and enforcing construction standards that account for liquefaction risks.
- Public Education: Raising awareness about the signs of liquefaction and appropriate emergency responses.
Sri Hidayati, head of earthquake mitigation at Indonesia’s Geology Agency, emphasizes, “If everything in the future is planned based on this, I think maybe we will only experience a small number of casualties in case such a disaster occurs again.”
Read also: Breathtaking Bamboo Building Withstands Earthquakes
Soil liquefaction is a silent threat, often overlooked until tragedy strikes. In Southeast Asia, where the ground beneath our feet can betray us without warning, awareness and preparedness are our best defenses. By understanding the risks and taking proactive measures, we can hope to prevent future disasters and protect our communities from this hidden peril.
