When designing the model, Sekiya divided the motion so that each of the three wires represents different time periods: the leftmost path is the motion of the particle for the first twenty seconds, the middle path is the motion for the next twenty seconds (Image 1) and the rightmost path is the motion for the following thirty two seconds. Labelled tags on the wires show the particle's position each second, which gives some idea of its speed and acceleration.
Although this model only covers the first 72 seconds, the earthquake motion continued for some time after Sekiya stopped modelling it. As the motion was then occurring in just one plane, Sekiya did not represent it in this 3-dimensional model.
It may not be obvious from the model, but the 'earth-particle' of the title is not a real one. It is a hypothetical particle - a representation of what would happen to a real particle. The motion of the earth-particle was created using the measurements from three separate instruments, each recording a part of the earthquake's motion.
