Kuala Lumpur sinkhole: Residents worried about safety but experts caution against speculation, suggest preventive measures

KUALA LUMPUR: Since last Friday (Aug 23), money changer Noor has felt fear whenever she steps out of her workplace on Jalan Masjid India.
“When I am in the building, I feel safe but when I am walking outside, I feel afraid … I am looking at the ground in fear,” said the mother of two, who has been working in the bustling area for about 10 years. 
An Indian tourist fell into a sinkhole in front of Malayan Mansion last Friday morning, mere metres from where Ms Noor works. While she did not witness the incident, she has watched the video of what happened and worries the same could happen to her.
“I don’t know how many times I have walked on that exact spot. Sometimes in the morning, I am seated on that bench next to the spot while waiting for the shop to open,” said Ms Noor, who declined to provide her full name.
On Fridays, thousands of Muslims would also attend prayers at Masjid India, spilling out to the surrounding area with their prayer mats, added Mr Hairul Hizwan, 34, who runs a stall selling Malay kueh, drinks and coconut water.
“I can only imagine if the incident had occurred then,” he told CNA.
Ever since the incident, the area – home to several department stores and goldsmiths – has been shunned by locals and tourists alike. 
Ms Noor said business at her shop has plunged by nearly 90 per cent. “This is a tourist area where thousands (typically) come for shopping because of the competitive prices,” she said.
Mr Hairul, who has been operating there for the past 15 years, could easily sell 400 curry puffs a day before the incident. In recent days, he has sold less than half that amount.
“Like it or not, I must come here. I earn a daily wage and don’t have a fixed monthly income,” he lamented. “I don’t know how long this will be for.”
Mr Mohd Zuri Yusoff, a security guard at the Malayan Mansion, said he was shocked to hear about the incident as the walkway was used by thousands of people daily. 
“I am definitely more careful now when I walk around the area,” he said, adding he would also continue to show up for work.
While this is not the first time a sinkhole has appeared on the street – a similar cave-in occurred about 50m away just last month in front of the Masjid India community police station – the heightened worry is because last Friday’s incident claimed a victim, they believe.
The search for the 48-year-old victim, identified as Ms Vijayaletchumy, entered its fifth day on Tuesday (Aug 27) with rescuers doing more flushing of the surrounding manholes and searching the Pantai Dalam treatment plant 7km away, where the sewer ends.
Separately, another cave-in occurred on Aug 27 in the Kuala Lumpur suburb of Kampung Kerinchi, along Jalan Pantai Permai, due to a collapsed drain. No casualties or injuries were reported.
Malaysian social media has been abuzz with netizens sharing past research findings of the Malaysian capital being susceptible to sinkholes, landslides and rockfalls due to its geology. 
According to a 2017 study by researchers from the Universiti Teknologi MARA’s Faculty of Architecture, Planning and Surveying, Kuala Lumpur has two different geological formations: The Kenny Hill Formation which consists of sedimentary rocks, and Kuala Lumpur Limestone Formation with “highly erratic karstic constituents”. 
Rapid development over the past 158 years has led to “specific changes in topography and geomorphology such as the appearance of sinkholes”, the study stated. Sinkhole hazard has “increased dramatically” since 1968 in Kuala Lumpur and Ampang, it added.
While sinkholes cannot be completely prevented, the authors said they can be systematically managed, such as by accurately mapping hazard zones before any development takes place.
Many cities around the world are, in fact, built on limestone, said Dr Lim Choun Sian, senior researcher at the Universiti Kebangsaan Malaysia.
“It is not really a red flag to build on limestone,” he told CNA. “You must make sure that the design and construction is based on proper investigations and there must be proper mitigation measures in place.”
The cause of last Friday’s incident is still not known, experts noted. 
While the city’s widespread limestone bedrock is well-known, this does not apply to all areas of Kuala Lumpur, noted Dr Nor Shahidah Mohd Nazer, an expert in geological engineering and soil mechanics.
Agreeing, Dr Lim said that it has not been established that the Masjid India area is built on limestone.   
“It is possible that it is, but we can’t say until there are checks. People are just making guesses that it is, because almost half of Kuala Lumpur is on limestone,” he said. 
“We have to establish the kind of geology and conduct thorough investigations.”
Even if the incident site is built on limestone, which is prone to dissolution, this does not happen overnight, said Dr Nor Shahidah of the Universiti Kebangsaan Malaysia. 
“We are talking about the geological time scale here so maybe hundreds, thousands or even a million years,” she said, adding that she disagreed with claims circulating online that Kuala Lumpur is unsafe and there was potential for a “giant sinkhole” to emerge at any time.
“The area is close to a major river confluence so ground saturation and underground water flow could potentially exacerbate undercutting erosion and (cause) part of the soil stratum to be hollowed,” she added.
The day before, several areas of Kuala Lumpur including in the city centre had been hit by flash floods following heavy rain. 
The Institution of Engineers, Malaysia (IEM) also noted in a statement after the incident that the sinkhole appears to be about 24m from Klang River.
That said, cave-ins can also be human-induced, said Dr Lim. A 10m-deep sinkhole on a road in the Golden Triangle area of Kuala Lumpur in 2014 was caused by a burst water pipe, for instance.
Based on photos and videos taken of the Jalan Masjid India site, last Friday’s incident could be associated with utilities, IEM president Jeffrey Chiang Choong Luin said on Sunday.
There have been several similar incidents in Kuala Lumpur in the past few years, but they may not have been reported as the cave-ins “didn’t swallow people or cars”, added Dr Lim.
Despite reassurances by Kuala Lumpur mayor Maimunah Mohd Sharif, the question on many people’s minds is whether Kuala Lumpur – a city of almost two million inhabitants – is structurally safe. Greater Kuala Lumpur, also known as the Klang Valley, has a population of almost 9 million people.  
Experts CNA spoke to did not disagree with Dr Maimunah, who had said Kuala Lumpur has been developed for a long time and claims that it was unsafe for development must be backed up by strong evidence. 
Most of Kuala Lumpur’s construction would have adhered to certain standards, Dr Lim noted. 
“You can’t simply build modern buildings. There are a lot of underground trains in the city and digging (of) the tunnels couldn’t have been done without the proper investigations, many of which have been done by international experts. 
“Accidents happen but they don’t only happen in Malaysia,” he said.      
A task force that includes the Department of Minerals and Geosciences, Kuala Lumpur City Hall, the Royal Malaysia Police and the Public Works Department has been set up to study the safety of development in the capital, Dr Maimunah said on Sunday.
Last Friday’s incident is a reminder to observe rigorous engineering standards, as well as an opportunity to reassess heavily developed areas in light of climate change, experts said.
It has shown the importance of keeping to best practices in the design, construction and maintenance of underground utilities, IEM’s Dr Chiang said in a statement on Aug 25. 
He told CNA that local authorities, particularly the Kuala Lumpur City Hall, should look into the mapping of ground conditions using sonar or geophone mapping, especially in key areas where there are high concentrations of people.
“Of course there will be a cost to it but this would … alleviate the concerns of people,” he said.
Dr Nor Shahidah said there is a need to address urban geology issues that have come to the fore because of climate extremes. 
“Areas with heavy development need to be reassessed in order to understand their current ground instabilities status,” she said. 
Residents living in some sinkhole-prone areas have also urged Kuala Lumpur City Hall to publish the city’s underground mapping system so they can be informed of the infrastructure lying beneath their neighbourhoods, local media reported.
Civil society group Save Kuala Lumpur’s chairman M Ali said Bangsar, Federal Hill and Brickfields have been “prone to sinkholes for decades, with some occurring in quick succession within days”, news outlet The Star reported. 
By publishing the city’s underground mapping system, Kuala Lumpur City Hall can “promote transparency, accountability and, most importantly, safety”, Brickfields Rukun Tetangga chairman SKK Naidu told The Star.
Like them, Ms Noor, the money changer along Jalan Masjid India, wants to feel safe again.
“There are so many buildings here. What if the land below the buildings is not stable? Could the buildings here collapse suddenly and cause more loss of life?” she asked.