Johor's recent earthquakes and what they mean for data centres

Johor was hit by a mild earthquake this morning, the third in four days. What does this mean for the massive cluster of data centres there? As I wrote recently, Johor has 13 operational data centres, with another 15 under construction.

News of the recent earthquakes in Johor has been making the rounds, especially among WhatsApp chat groups of data centre professionals. Here's my take on it.

Cloudy with a trio of earthquakes

Here's what we know so far. A mild earthquake struck Johor this morning, with tremors felt in parts of the state and southern Pahang, according to the Straits Times.

The sequence: August 24 at 6.13am brought a 4.1-magnitude quake, followed by a 2.8-magnitude at 9am the same day. This morning, August 27 at 8.59am, saw a 3.2-magnitude event.

Experts say the recent quakes are likely "intraplate" ones caused by a minor fault within the Sunda Plate. These are less common and usually not as destructive as quakes at tectonic plate boundaries. Today's tremor is likely an aftershock of the earlier quakes.

It's worth noting that earthquake magnitude on the Richter scale is measured logarithmically. This means a magnitude 6.0 earthquake releases thirty-two times more energy than a 5.0, and nearly a thousand times more than a 4.0. A 4.0-magnitude quake, though noticeable with minor shaking indoors, is considered minor and unlikely to cause significant damage.

Data centres in earthquake zones

How are data centres built in earthquake zones? I wrote about this in a recent post on Japan, where earthquake-resistant construction is a must. Broadly speaking, there are two main approaches: at the structural level or rack-level of the data centre.

At the structural level, techniques such as base isolation offer the most robust protection. This requires creating seismic isolators between the structure and foundation, essentially allowing the building to move independently from ground motion.

At the rack level, operators use isolated pads, seismic-rated cabinets and floor anchors to prevent racks from toppling. Flexible coupling for pipes prevents leaks during movement. In a nutshell, it's a lot of work and additional expense.

Impact to Johor

For now, I expect the data centre community to adopt a wait-and-see approach. This is because earthquake resistance cannot be easily retrofitted into existing data centres. You either build it in from the start or you don't.

It's also worth noting that Johor is not generally classified as an earthquake zone, so this is highly likely to be an isolated incident. The region hasn't historically required seismic considerations in construction standards.

Here's something to mull over: the chance of an intraplate earthquake in Singapore is non-zero. Though the likelihood of one is "very low," there isn't enough data to rule out the possibility of a once-in-500-year or even once-in-100-year event.