answer:“Preliminary data published by the USGS show that the largest of the series of the tremors, which occurred 21 miles from the town of Shawnee, had a magnitude of 5.6. It had been preceded by a series of minor tremors, with dozens of smaller events recorded in the area: all occurred at a shallow depth, around 5km. :Decoded Science “Earthquakes produce two types of seismic waves through the earth. P waves move the eatrh’s surface mainly up and down, and S waves move it mainly side to side. The P waves travel faster so they arrive first. As the P waves arrive at your location, they cause the ground surface around you, and your floor, to vibrate up and down, just like a loudspeaker cone. The movement is too tiny to be seen, but just large enough to cause a low frequency sound. These sounds are often described as a boom or rumble. ” Leonard Geophysical Observatory