The recent sinkhole incident at Masjid India has brought to light the significant impact of urban development on city landscapes, raising concerns about the underlying risks of human activities. This particular sinkhole, classified as anthropogenic, underscores the potential dangers lurking beneath urban environments.
Universiti Kebangsaan Malaysia’s (UKM) Geohazard and Engineering Geology expert, IR Dr Goh Thian Lai, explains in a news report that a sinkhole is essentially a depression in the ground without any natural external drainage.
Rainwater collects and drains into the subsurface, often leading to these sudden ground collapses. Sinkholes are most commonly found in karst terrain, where rocks such as limestone, gypsum, and salt beds can dissolve due to groundwater circulation. Drawing example from another country like the Florida state, in the United States, with its extensive limestone foundation is susceptible to sinkholes. As rainwater permeates the soil, it dissolves these rocks, creating underground voids that eventually collapse.
Dr Goh points out that the Masjid India sinkhole was caused by human activities rather than natural processes. The primary cause was the burst of a 1.5-metre sewer pipe. Although the exact reason for the burst remains unclear, it is evident that water flowing through the broken pipe gradually eroded the material beneath the walkway, creating a hollow space and subsequently leading to the sinkhole.
Natural sinkholes can also form due to factors such as rapidly lowering groundwater tables or ground vibrations from human activities like piling, quarrying, major construction projects, or seismic activity. While Malaysia experiences mild tremors from earthquakes in Indonesia, local earthquakes triggered by fault reactivation can also contribute to sinkhole formation. In non-limestone areas, heavy rains are unlikely to cause natural sinkholes; however, anthropogenic sinkholes can form if water infiltrates underground channels, tunnels, water pipes, drainage systems, or sewer pipes. A rapid drop in the groundwater table can trigger both anthropogenic and natural sinkholes.
In limestone areas, karst terrain naturally predisposes the land to sinkhole formation. For instance, Kuala Lumpur is underlain by the KL Limestone and Kenny Hill Formation, with limestone predominantly found in the northern part of the city. Developments in these areas require extensive soil investigations to identify cavities and fractures. Techniques such as field identification and geophysical methods are employed to assess potential sinkholes. Once detected, engineering measures like injecting epoxy, concrete, or grout into the cavities are implemented to prevent sinkholes.
The search for 48-year-old Indian tourist Vijayaletchumy, who fell into an eight-metre-deep sinkhole on Jalan Masjid India, continues. Despite extensive search and rescue operations involving scuba divers and a new flushing technique to clear blockages, no new leads have emerged. Vijayaletchumy disappeared on August 23 while walking towards a nearby temple, with CCTV footage capturing the moment she vanished into the sinkhole. Authorities have raised safety concerns but assured that Kuala Lumpur remains safe, with search efforts ongoing indefinitely until she is found.
This incident has sparked discussions about the broader implications of urban development on city infrastructure and public safety. It highlights the need for rigorous monitoring and maintenance of underground systems to prevent similar occurrences in the future.
Urban planners and engineers must consider these findings when designing infrastructure in vulnerable areas. Implementing advanced monitoring systems and employing preventive measures can significantly reduce the likelihood of sinkholes. Furthermore, public awareness campaigns can educate communities about the signs of potential sinkholes and encourage prompt reporting of any suspicious ground depressions.
As cities continue to expand and evolve, striking this balance becomes increasingly important. Ensuring that development projects incorporate thorough geological assessments and robust safety protocols will be key to safeguarding both infrastructure and lives.
While urban development brings numerous benefits, it also poses certain risks that must be carefully managed. The Masjid India sinkhole is a testament to the need for vigilance and proactive measures in urban planning. By learning from such incidents and applying scientific knowledge effectively, cities can continue to grow while minimising geological hazards.
