Editing Leaning Tower of Pisa (section)

== Earthquake survival ==
The tower has survived at least four strong [[earthquake]]s since 1280. A 2018 engineering investigation concluded that the tower withstood the tremors because of dynamic [[soil-structure interaction]]: the height and stiffness of the tower combined with the softness of the foundation soil influences the tower's vibrational characteristics in such a way that it does not [[Mechanical resonance#Resonance disaster|resonate]] with [[Strong ground motion|earthquake ground motion]]. The same soft soil that caused the leaning and brought the tower to the verge of collapse helped to prevent significant destruction in the event of an earthquake.<ref>{{cite web |url=https://www.sciencedaily.com/releases/2018/05/180509105004.htm |title=500-year-old Leaning Tower of Pisa mystery unveiled by engineers |website=ScienceDaily |date=9 May 2018 |access-date=22 November 2018 |archive-date=22 November 2018 |archive-url=https://web.archive.org/web/20181122172017/https://www.sciencedaily.com/releases/2018/05/180509105004.htm |url-status=live }}</ref>