An Earthquake Swarm
Seismic waves were found all around the world on November 11 and scientists still aren't sure of what to make of it. The U. S. Geographical Survey detected waves in Ethiopia, New Zealand, Spain and Zambia for twenty minutes. Usually these kinds of low-frequency signals are the result of volcanic activity. Researchers say that they've never seen anything like this, given that usually earthquakes release a big burst of energy followed by different types of waves afterward. But there was no earthquake to generate these waves, which are unlike any others ever measured before.
