HONG KONG, Oct 31 (Reuters) - Earthquakes not only shake the ground from side to side, they hoist it up and down as though the earth is bouncing on a trampoline, researchers in Japan found. The scientists found evidence of the jarring vertical movements from analysing data recorded by seismographs during a powerful earthquake that struck northern Japan on June 14. That 7.2 magnitude quake struck a remote hot spring resort, killed at least 9 people and left more than 200 injured. The scientists likened the vertical movement of the quake to an athlete bouncing on a trampoline. "There are two forces acting on the athlete, namely the downward-directed gravity and the upward-directed repulsion of the trampoline hit by the athlete," they wrote in the article published in the journal Science. "The trampoline's repellent force is larger than gravity," they said leading to vertical movements. They hoped the findings would help engineers design buildings that can withstand strong motion, both horizontal and vertical, in earthquake-prone zones. (Reporting by Tan Ee Lyn; Editing by Sanjeev Miglani)
Survivors wait for their turn during the distribution of relief goods near Ziarat, October 30, 2008. Pakistani army helicopters scoured mountains on Thursday for survivors of a powerful earthquake that struck ...
