Is it possible for an earthquake to generate such a design in a sand pendulum during an earthquake? I saw an article online describing the story of a shop owner finding one of his pendulums had created this image during an earthquake.
I researched seismographs and they all seem to be in a linear fashion. Obviously a pendulum is not a scientific seismograph which raises the question: is this possible?
I could not find any research debunking this concept nor confirming. All the articles I read were different news groups reiterating the same story.