Damage expert in Turkey: ‘You can build earthquake-resistant buildings’

Thousands of buildings have collapsed as a result of the terrible earthquake on the Turkish-Syrian border, and many people are believed to still be trapped under the rubble. Mohammad Kashani, a professor of civil and seismic engineering at Britain’s University of Southampton, told Britain’s science media center SMC that some of the collapsed structures may not have been designed to withstand such strong vibrations because they were built before modern seismic standards were introduced. Photos indicated this.

However: the strongest quake recorded on Monday morning reached a magnitude of 7.7. “In principle, buildings can be constructed to withstand magnitudes of 7 and above,” said earthquake engineer Pia Hannewald, president of the Swiss Society for Earthquake Engineering and Structural Dynamics SGEB. However, whether this happens depends on the local seismic hazard and the importance of the building.

In Europe, “Eurocode 8” is the recommended standard for earthquake-resistant construction. The goal is to build the buildings to withstand an earthquake of the magnitude that statistically occurs every 475 years. “So there is no such thing as 100% certainty, since with the correspondingly low probability, an earthquake can also occur that is only expected to occur every 2000 years.”says the earthquake engineer.

A construction method common in Switzerland allows damage to buildings from earthquakes of magnitude 5 or more, with destructive damage starting at magnitude 6. “However, the situation is different for important buildings such as acute hospitals or hospitals. nuclear power plants. Much higher safety standards apply there,” says Hannewald.

In 2004, as a result of the devastating earthquake in Izmir, the Turkish government passed a new law requiring all buildings to meet modern earthquake-resistant standards. “Following the recent event, it will be important to check that all buildings built since then are compliant, that requirements are adequate and that there are ways to improve the security of older buildings,” said Joanna Faure Walker of University College London. , the science media center SMC.

Certain structures are better protected against earthquakes than others. “For earthquake-resistant construction, building materials that deform during an earthquake and do not immediately fall apart are well suited,” explains Pia Hannewald.

Wood, reinforced concrete or well-designed masonry buildings are suitable for this. The other possibility is structures with high resilience. This can be achieved with many continuous walls and steel cables with cross connections. “In regions particularly prone to earthquakes, a seismic isolation layer is sometimes placed between the subsurface and the foundation, which can absorb a certain horizontal displacement of the ground,” says the earthquake engineer.

On the other hand, buildings with irregular structures are unfavorable. This is the case, for example, if the ground floor has hardly any walls because it contains a large entrance hall. Old buildings whose structure has decayed are also critical.

Hannewald says there are still buildings in many countries that are not built to the latest earthquake-resistant standards, including Switzerland. Because the renovation and reinforcement of the housing stock does not happen overnight. However, it is a misconception, as the earthquake engineer emphasizes, that earthquake-resistant construction is also very expensive: “People expect an additional cost of 1 to 2 percent on the supporting structure of a building.”