How to choose a home in an earthquake zone

Seismologists everywhere repeat this line, and it is not a metaphor. Shaking of the same strength cracks plaster in one town and folds houses in another. The difference lies in how a building was built, what it stands on, and what condition it is in.

Which leads to an uncomfortable conclusion: the decision that most affects your safety in an earthquake is not made during the shaking, nor while packing a go-bag, but on the day you sign for a flat. And you have time to think about that one.

What follows is what a non-engineer can check. It does not replace a professional survey, but it filters out the worst options before you fall in love with the view.

A wave arriving from depth behaves according to what it passes through in its last few tens of metres. Rock transmits the motion sharply and briefly. Loose sediment — an old river bed, a filled ravine, reclaimed shoreline — resonates and amplifies the wave, sometimes several times over. Buildings on such ground take substantially more than their neighbours on rock.

A distinct hazard is liquefaction. Water-saturated sand temporarily loses its bearing capacity under shaking and behaves like a liquid: the building tilts or sinks as a whole while remaining structurally intact. Those images of leaning but undamaged blocks are exactly this. The risk is higher near coasts, rivers and on drained land.

Ask about the ground survey for the plot. For new build it should exist in the project documentation. Simple observation helps too: find out what was on the site before, and look at how neighbouring buildings are faring — cracks on the façades next door say more about the ground than any developer's brochure.

Seismic codes have been revised after every major disaster, and what was built later is on average stronger than what came before. In Türkiye the key threshold is the destructive earthquakes of 1999, after which the codes and the building inspection system were substantially rebuilt; a further major revision of the code followed in the late 2010s.

But the year in a listing is only a year. A code works if it was built to and if the site was supervised. The destruction in 2023 included relatively new buildings that collapsed completely — where the design was departed from, where steel and concrete were skimped on, or where unauthorised alterations were regularised after the fact.

So the year is a first filter, not a closing argument. It needs documents and an inspection alongside it.

Look at the building from outside. If the ground floor is continuous shop glazing, a car showroom or open parking while the floors above are ordinary flats with walls, that is a soft-storey structure. The upper floors are stiff because of their partitions; the bottom one is held by columns alone.

In shaking, all the deformation collects in that weak layer. The building does not disintegrate from the top down — it sits down: the ground floor disappears and the floors above descend into its place largely intact. That is what most of the collapses you have seen in disaster footage look like.

This does not doom every building with shops underneath: the arrangement can be designed for and strengthened. But if the owner cannot show that it was accounted for, treat the risk as high.

Simple and symmetrical beats complicated. A rectangle in plan behaves predictably; L-shaped buildings and those with re-entrant corners twist under shaking, and stress concentrates at the kink. Abrupt setbacks in height, upper floors cantilevered over the pavement, storeys added later — all of it worsens the structure's behaviour.

Inside, look at columns and load-bearing walls. Warning signs: diagonal or cross-shaped cracks on columns and at the corners of openings, fresh plaster precisely in those places, evidence that a column was cut into or worked around during a refit, load-bearing walls removed to merge rooms.

Short columns deserve their own mention. When a column is partly gripped by a spandrel wall or partition, only a short length is free, and the whole demand lands on it. Those columns fail first. From outside it looks like a row of narrow windows just under the ceiling of a basement or ground floor.

A building permit and an occupancy certificate show that the building was built legally and formally accepted. Their absence is not a bureaucratic detail: it means nobody checked the building and that authorised information about its structure may not exist at all.

Ask about the building inspection report, the design documentation and the ground survey. An owner is not obliged to have kept all of it, but the reaction to the question is informative in itself.

Compulsory earthquake insurance for dwellings exists in Türkiye as a separate policy, often required for transactions and utility connections. Having it does not make a building stronger, but it indicates the property is properly registered.

For an older building, ask whether a seismic assessment has been carried out and whether the block falls under any programme for replacing unsafe housing. A negative answer is not a verdict, but it is reason to commission an independent assessment before the deal rather than after.

This is the most frequently asked question, and the honest answer is that the quality of the building matters many times more than the floor. A bad building is dangerous at every level; a good one holds at every level.

That said, upper floors sway more: greater amplitude, furniture thrown harder, and a harder exit if the lifts are dead and the stairs are damaged. Lower floors carry more of the structure's weight and are the first to suffer in a soft-storey collapse. The first floor above shops is the worst of both lists.

The practical conclusion: do not let the choice of floor substitute for checking the building. But if the building is doubtful and there is no alternative, remember that upper floors are harder to leave — which matters most for older and less mobile people.

Direct questions save months. When was it built and to which code. Is there an occupancy certificate. Has a seismic assessment been done and is there a report. Have there been alterations affecting the structure, and were they authorised. Have storeys been added. What was on the plot before it was built on.

Evasive answers to these are answers in themselves. The seller of a sound building answers readily, because it is an argument for the price.

Not everything is solved by moving, and panic serves nothing. Start with what is within your control: anchor the furniture, take heavy things off high shelves and from above beds, assemble documents and a go-bag. That lowers the risk of injury regardless of the structure.

Then find out whether the building has been assessed, and discuss commissioning one with your neighbours. Decisions about strengthening or rehousing are taken by owners collectively, and one active resident is often where it begins.

And think the worst case through soberly: work out the way out, agree a meeting point with your family, know where the gas shuts off. These are the same measures as in the preparation article, but in a building of doubtful construction they count for a great deal more.