Seismic engineering experts have pointed out that a very dangerous phenomenon called a "pancake crash," in which buildings collapse vertically, may have exacerbated the damage caused by the earthquake in southern Turkey.
Koichi Kusunoki, a professor at the Earthquake Research Institute of the University of Tokyo who has experience conducting surveys in Turkey, commented on the damage to buildings caused by the earthquake, saying, "Various buildings, ranging from low-rise to middle-rise buildings, have collapsed. Among them, pillars have lost their strength instantaneously. At some points, a very dangerous collapse called a 'pancake crash' occurs, where the entire building collapses to the bottom."
Below is an image of the "pancake crush" mechanic.
The strong shaking instantly breaks the pillars of the building as if they were exploding.
And each floor of the building will collapse so that it folds.
According to Professor Kusunoki, when a pancake crash occurs, people in the building have no time to escape, so ``the damage may have expanded.''
According to Professor Kusunoki, there are many earthquakes in Turkey, and the current earthquake resistance standards are at the same level as in Japan, but there are many old buildings with low earthquake resistance from before that.
In the future, it will be necessary to investigate in detail the relationship between the construction age of the building and the causes that led to the extensive damage.
He also noted the damage caused by multiple housing complexes collapsing in the same direction, suggesting that the strong shaking may have acted in one direction and that further analysis is required.
Professor Kusunoki pointed out that there was a possibility that even buildings that met the Japanese seismic standards could have suffered major damage in this earthquake, and he said, "Even though very large earthquakes are rare, they do occur suddenly in both Turkey and Japan. It's the same.Although Japan's seismic diagnosis and reinforcement are progressing, there are still buildings that were designed according to old standards.It is very important to further promote seismic reinforcement."
“Intense tremors equivalent to Japan’s seismic intensity of 7”
Masafumi Shiomitsu, an assistant professor at Yamagata University who specializes in earthquake engineering, used seismometer data obtained from about 30 observation points in Turkey for an earthquake with a magnitude of 7.8 that occurred shortly after 10:00 a.m. Japan time on the 6th. Analyzed.
As a result, it was found that severe shaking equivalent to a "seismic intensity 7" in terms of Japanese seismic intensity was observed in Hassa, Hatay Prefecture, which is about 60 kilometers southwest of the epicenter, which is directly above the epicenter.
Earthquakes with a seismic intensity of 7 were observed in the Great Hanshin-Awaji Earthquake in 1995, the Great East Japan Earthquake in 2011, and the Kumamoto Earthquake in 2016, all of which caused extensive damage.
It was also found that the shaking equivalent to seismic intensity "6 strong" and "6 weak" extended to a range of about 160 km in length near the epicenter.
Regarding the period of the tremors, tremors of about 1 to 2 seconds were observed, which could cause serious damage to relatively large structures such as middle-rise buildings in Japan.
Assistant Professor Shiomatani said, "It is thought that the severe tremors with an intensity of 6-upper to 7 on the Japanese seismic scale, which can cause severe damage to buildings in Japan, caused the great damage. We need further verification."