Earthquake in Japan was as strong as one in Turkey – expert explains differences between national mourning and search for perpetrators in Iran after attack that killed dozens

On January 1 this year, the earth shook in Japan. The magnitude of the earthquake was 7.6. The current number of victims is 81 people. About a year ago, two earthquakes of magnitude 7.5 and 7.8 shook Turkey. They were almost as strong as the recent earthquake in Japan. But in Turkey more than 50,000 people died.

Why can equally strong earthquakes have such different effects? Florian Haslinger is deputy director of the Swiss Seismological Service and puts things into perspective.

The most recent earthquake in Japan claimed relatively few victims. Experts say the number of deaths can be controlled through proper preparation. What measures are essential in an emergency?
The damage pattern depends on many factors. Earthquake-resistant construction is important and the infrastructure in the countries also plays a role. When an earthquake occurs, it is also important how quickly rescue workers can be mobilized. But if certain roads are destroyed, this obviously makes the work more difficult. And: The population must also be well educated.

How does a ‘well-educated population’ behave in such a strong earthquake?
If the shaking starts and you are in a house that does not collapse immediately, you should take shelter under a table. This way you won’t be hit if, for example, a lamp or something like that falls from the ceiling.

The earthquakes in Turkey on February 6, 2023 had magnitudes of 7.8 and 7.5. The one in Japan 7.6. More than 50,000 people have been killed in Turkey. In Japan, the number currently stands at 81 deaths. Why is there such a difference?
Fires have also broken out in Japan and houses have collapsed. This shows that even with good preparation, damage can occur. The relatively low number of deaths is mainly due to the fact that the population density in the affected area was lower. In Japan, the earthquake fault zone does not pass through densely populated areas. In Turkey the area was much more densely populated.

Infrastructure certainly makes a big difference, right?
Yes, the houses in Japan are most likely built to be more earthquake resistant than those in Turkey. This means that even if some houses have collapsed, there are not as many as in Turkey.

Which other earthquake regions are as well prepared as Japan?
That is very different. The economic strength of a country and its social structure determine this. In many countries, preparation for major earthquakes is not very good. Simply because of the structure of the building. The 2010 earthquakes in Haiti were less intense than those in Japan at a magnitude of 7, but caused a devastating catastrophe because Haiti and other countries are ultimately too poor to properly prepare. Other regions are on the right track: other countries in the Pacific Ring of Fire, such as Chile or the US, are already good at dealing with earthquakes.

How often do earthquakes of magnitude 5, i.e. medium magnitude, occur in these regions?
Level 5 earthquakes happen every day at some point, but generally strike more frequently in regions where earthquakes occur more frequently. Earthquakes with a magnitude of 5 actually rarely cause damage. But there are exceptions, for example in Afghanistan or Pakistan, earthquakes between levels 5 and 6 can cause damage, because in these areas there are many clay houses that are not so stable and are destroyed.

An earthquake is also expected to occur in Istanbul in the next decade. Why can’t you accurately predict the time of the earthquake and its magnitude?
We don’t know well enough yet how to prepare for earthquakes. An earthquake occurs when tension builds up in the Earth’s crust. These discharge at some point, usually into existing fault zones. This causes the earth’s plates to slide past each other, causing an earthquake. But exactly when these tensions become so great that this derailment occurs, that is, the trigger, is not known in detail. We have not yet found a method to measure this in detail or to make precise predictions about exactly when a specific earthquake will occur.