HDB blocks fitted with tremor sensors

Devices placed in 46 blocks to track quake vibrations, alert HDB

By Amelia Tan Hui Fang & Lee Jia Xin, The Straits Times, 2 May 2012

THE tremors were so strong, the bed was shaking and she could hear the door chain rattle.

Ms Ida Jamil recalled how she felt nauseous as the vibrations from a 7.6-magnitude earthquake off Sumatra shook her Sengkang flat in 2009.

'We were so worried; it was the first time I felt such a strong tremor,' said the 34-year-old civil servant.

To deal with the concerns of residents like Ms Ida, sensors that monitor tremors have been installed in 46 blocks of Housing Board flats across Singapore.

When the sensor detects seismic vibrations, the device sends a text message alert to the HDB.

Engineers are then sent to inspect the buildings to ensure that they remain structurally sound.

Responding to queries from The Straits Times, a HDB spokesman said last week that the sensors are an 'additional safety precaution' rather than an early warning system for earthquakes.

Work to install the sensors began in 2007. Ms Ida's block in Sengkang was installed with the sensors in March this year and is one of the more recent blocks to have the system.

Experts like Professor Richard Liew, programme director at the department of civil engineering at the National University of Singapore, said the sensors are a long-term measure to monitor the health of buildings.

The sensors detect ground vibrations, which are in turn affected by several factors - the height of the structure, construction materials, ground conditions and the type of building.

Prof Liew added that data collected from the sensors can be used to determine whether an earthquake code of practice is needed in future. Unlike countries such as the United States, Singapore has not adopted an earthquake code as it is outside the quake zone.

The HDB is not the first agency here to install tremor sensors in buildings.

The Building and Construction Authority (BCA) has also been running a pilot study looking into how buildings respond during tremors since 2006.

Sensors used by the BCA, which measure how intensely building structures vibrate, have been installed in 36 commercial and residential buildings islandwide.

Mr Ong Chan Leng, director of BCA's special functions division, said the sensors complement inspections by engineers in the event of tremors.

No building in Singapore has been structurally affected by earthquakes, said the BCA.

Meanwhile, residents in Sengkang said they now feel safer because of the tremor sensors installed by the HDB.

'It's good to know that measures are taken - sometimes, we don't feel the vibrations, but these readings will tell,' said estate agent Andrew Yeo, 57.

Ms Ida's husband, Mr Mohd Anis, agreed. The 36-year-old civil servant said: 'At least there's a proper system in place now, rather than just a visual inspection. It's a good move.'