The earth gives off a repeating seismic pulse every 26 seconds.That sounds like nonsense until you realize seismologists have been tracking it for decades.It’s called a micro-seism.A faint, repeating vibration moving through the earth, picked up by instruments around the world.The source has been traced to the Gulf of Guinea, off the west coast of Africa. The cause is still debated. Some researchers point to ocean waves interacting with the seafloor. Others have looked at volcanic, magmatic, or