Here's Why Earthquakes' 'Four-Leaf Clover' Shockwaves Are Dangerous Instead of Lucky - ScienceAlert
Geologists have measured a devastating 'four-leaf clover' pattern of earthquake shockwaves in greater detail than ever before – and the resulting findings could be crucial in making our buildings and cities more resistant to large quakes in the future.
By using algorithms to filter shockwaves by frequency, the four-leaf clover pattern emerged, but only at the lower frequencies.That might be because lower frequency seismic waves can bypass the jumble of broken rock found at earthquake faults, rather than being reflected and scattered in many different directions.
It shows that while people on the ground might experience a consistent level of shockwaves (the higher frequency ones), the buildings around them might be under a greater or lesser level of stress (the lower frequency shockwaves), depending on where they are in the four-leaf clover pattern.