Kahramanmaraş Earthquake Sequence of 6th of February is the deadliest earthquake that happened in Turkey in the era of instrumental seismology, claiming more than 55 thousand lives and leaving torn down cities and towns behind. More than 450 km long lateral strike-slip fault ruptured during these catastrophic earthquakes. As a result, more than 38 thousand buildings collapsed causing life losses. Considering that the large share of the Turkish building stock consists of RC buildings, the vulnerable RC building stock is the main responsible for this picture. Deficiencies of the Turkish RC building stock are well known since they manifested themselves several times in the past earthquakes. However, considering the improvements in the seismic codes and the seismic hazard maps achieved in the last two decades, the widespread collapse of buildings constructed after year 2000 was rather unexpected. Some of the observed structural damage patterns are similar to those observed also in the pre-2000 buildings in recent earthquakes, however, some other types of damages, such as out-of-plane bending and shear failures or shear-friction capacity failure of RC walls, brittle fracture and bond-slip failure of reinforcement, tension failure of beams and slabs are usually not witnessed. This paper presents a carefully selected set of examples comparing the pre-2000 and post-2000 building damages and collapses, also referring to a detailed summary and comparison of the code developments in Turkey.
I was somewhat surprized with the fog in Groningen upon my arrival. This is notthe fog that covers the beautiful landscapes of the northern Netherlands in theevening and in the early morning. No… It is the fog that obscures the real aspectsof the earthquake problem in the region and is crystallised in the phrase “Groningen earthquakes are different”, which I have encountered numerous times whenever I raised a question of the type “But why..?”. A sentence taken out of the quiver as the absolute technical argument which mysteriously overshadows the whole earthquake discussion.Q: Why do we not use Eurocode 8 for seismic design, instead of NPR?A: Because the Groningen earthquakes are different!Q: Why do we not monitor our structures like the rest of the world does?A: Because the Groningen earthquakes are different!Q: Why does NPR, the Dutch seismic guidelines, dictate some unusual rules?A: Because the Groningen earthquakes are different!Q: Why are the hazard levels incredibly high, even higher than most Europeanseismic countries?A: Because the Groningen earthquakes are different!and so it keeps going…This statement is very common, but on the contrary, I have not seen a single piece of research that proves it or even discusses it. In essence, it would be a difficult task to prove that the Groningen earthquakes are different. In any case it barricades a healthy technical discussion because most of the times the arguments converge to one single statement, independent of the content of the discussion. This is the reason why our first research activities were dedicated to study if the Groningen earthquakes are really different. Up until today, we have not found any major differences between the Groningen induced seismicity events and natural seismic events with similar conditions (magnitude, distance, depth, soil etc…) that would affect the structures significantly in a different way.Since my arrival in Groningen, I have been amazed to learn how differently theearthquake issue has been treated in this part of the world. There will always bedifferences among different cultures, that is understandable. I have been exposed to several earthquake engineers from different countries, and I can expect a natural variation in opinions, approaches and definitions. But the feeling in Groningen is different. I soon realized that, due to several factors, a parallel path, which I call “an augmented reality” below, was created. What I mean by an augmented reality is a view of the real-world, whose elements are augmented and modified. In our example, I refer to the engineering concepts used for solving the earthquake problem, but in an augmented and modified way. This augmented reality is covered in the fog I described above. The whole thing is made so complicated that one is often tempted to rewind the tape to the hot August days of 2012, right after the Huizinge Earthquake, and replay it to today but this time by making the correct steps. We would wake up to a different Groningen today. I was instructed to keep the text as well as the inauguration speech as simple aspossible, and preferably, as non-technical as it goes. I thus listed the most common myths and fallacies I have faced since I arrived in Groningen. In this book and in the presentation, I may seem to take a critical view. This is because I try to tell a different part of the story, without repeating things that have already been said several times before. I think this is the very reason why my research group would like to make an effort in helping to solve the problem by providing different views. This book is one of such efforts.The quote given at the beginning of this book reads “How quick are we to learn: that is, to imitate what others have done or thought before. And how slow are we to understand: that is, to see the deeper connections.” is from Frits Zernike, the Nobel winning professor from the University of Groningen, who gave his name to the campus I work at. Applying this quotation to our problem would mean that we should learn from the seismic countries by imitating them, by using the existing state-of-the-art earthquake engineering knowledge, and by forgetting the dogma of “the Groningen earthquakes are different” at least for a while. We should then pass to the next level of looking deeperinto the Groningen earthquake problem for a better understanding, and alsodiscover the potential differences.
