It is noted that sometimes, in an earth-quatke, short and tall strutures remain uneffected while the medium height structures fall down. Explain why?

Explanation

This happens because th naturela frequencies of the short structures happen to be higher and those of taller structure lower than the frequency of the seismicwaves. Due to it there is no resonant vibrations. He frequencies of medikium height structures is same as the frequencies of seismix waves, hence resonance takes place. The amplitude of oscillation of medium height structures becomes large and they collapse.