Prof. Ahmet Ercan explains: Why did some people in Istanbul not feel the earthquake?

The 4.1 magnitude earthquake that occurred off the coast of Çınarcık, Yalova, was felt by millions of citizens in Istanbul. 

However, while some people did not feel the earthquake, they learned about it from the morning news. 

ITU faculty member and Geophysical Engineer Prof. Dr. Övgün Ahmet Ercan explained the reason for this to Hürriyet columnist Fulya Soybaş.

"IT MUST BE INVESTIGATED, PRECAUTIONS MUST BE TAKEN"

Ercan stated the following:

“If one person living in the same building feels the earthquake and their neighbor does not, this could be a human factor. If you are in buildings across from each other and one of you feels it while the other does not, then this situation can be technical as well as human. As a geophysicist who has dedicated 54 years to earthquake research, in my opinion, many things are technical. It must be investigated, and precautions must be taken." 

DREW ATTENTION TO THE RESONANCE EFFECT

Explaining why feeling the earthquake varies from building to building even on the same street by using "resonance," Ercan noted the following:

"Resonance can be explained as the harmony between the ground and the structure. We call it resonance when the frequency created by the wave-pressure coming from the ground causes the structure to oscillate, or expand, more, leading to bending or gaps. For example, buildings taller than 2 stories built on young, wetter, more humid agricultural land can enter resonance more than buildings built on solid ground. You say, ‘Emre felt the last 2 earthquakes intensely.’ This means that the building Emre lives in has entered resonance, meaning it felt the frequency coming from the ground more. Emre also shook as much as his building felt that vibration and shook. Remember that it is not the fault rupture that destroys buildings, but the power of the seismic waves passing under the structure and the impact acceleration. If the vibration of the wave and the swaying of the building align (enter resonance), your house can be destroyed by excessive shaking/jolting. In other words, it is not a good thing for a structure to enter resonance."