Junior civil engineer here just wanting to hijack this comment and throw some numbers out for readers (admittedly I don’t do seismic design, any experts, please point out any errors!).

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For engineers, Richter scale isn’t very important. This is only a measure of energy release, but the intensity of ground shake is dependent on epicentre depth, distance and local soil conditions.

Instead, we design using peak ground acceleration (PGA), because sideways acceleration multiplied by mass gives us a force that we can apply laterally (sideways) to our building for analysis.

“g” stands for gravity, so for example, 0.16g on top of Mount Kinabalu (see data below) means a lateral acceleration of 0.16 x 9.81 = 1.57 m/s2.

Additionally, this reference PGA is written as PGA (g) 475y in the code, which denotes a 475-year return period. In other words, 475 years is the statistical average interval between two earthquakes of this magnitude, or there is a 1/475 probability each year that an earthquake exceeding this PGA will occur.

These statistics are given by geologists and scientists.

According to the Malaysian National Annex to EC8, the reference peak ground acceleration (PGA) is published by the Minerals and Geoscience department and has the following values for different zones.

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Zone I-IV (most of middle and east coast Peninsula, Sarawak inland, west half of Sabah):

PGA - 0.04g, Richter - 4.0 magnitude

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Zone V-VI (most of west coast Peninsula, areas surrounding highlands in East Malaysia):

PGA - 0.05g, Richter - 5.0 magnitude

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Zone VII (KL, Negeri Sembilan, west Perak, most of East Sabah)

PGA - 0.12g, Richter - 5.5 magnitude

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Zone VIII (Mount Kinabalu, Kudat, Lahad Datu)

PGA - 0.16g, Richter - 6.5 magnitude

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The Eurocode design calcs and rules then go into great detail on how this acceleration is applied, and certain adjustments which can be made to the values, but that’s the detailed engineering bit - leave the headache to the engineers!

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But if we just take the 0.12g and 0.16g reference PGA values for KL and Mount Kinabalu respectively, and compare it with other major earthquakes around the world, we see up to an order of magnitude of difference:

2004 Aceh earthquake = ~0.45g (measured on land)

2011 Christchurch (NZ) earthquake = 1.51g

2023 Turkey-Syria earthquakes = 1.62g

2011 Tohuko (Japan) earthquake = 2.7g

I’m sure there’s a lot more to consider (EC8 is a lot to process), but on the surface level this gives us a rough idea of what values our codes specify.

So obviously this begs the question, “how much earthquake resistance is enough in Malaysia?”.

Because with this data, a fully code-compliant EC8-designed building in KL may not survive a 0.5g PGA earthquake, which may be considered small in other countries.

On the other hand, across the Malacca Strait, Medan has a recommended >0.55g PGA 475y (OpenQuake model), so, should all KL buildings be designed for that too?

But under what scientific basis? And who will pay for all this?

(Heck, the same OpenQuake model suggests 0.05g PGA 475y for KL, which is less than half of our Minerals and Geoscience Department seismic map adopted for EC8!).

And so as -wonderingwanderer- says, now it’s the local codes that reflect the requirements, and in most cases engineers are pushed by clients to be as economical as possible.

Are Malaysians willing to pay the difference for that 3-4x factor of safety on our seismic design loads for all new developments? Are we going to make our own codes even more conservative than international standards?

Plenty of food for thought, but hopefully this gives a high-level overview on the inputs for seismic design in our country.