You didn’t feel it, or if you did, you’re the only person on earth, but a strange series of seismic waves rippled around the globe on the morning of November 11. The origin seems to have been off the coast of Africa near Madagascar. Quickly, the waves sped across the African continent and sent sensors buzzing in countries throughout the Western Hemisphere. For 20 minutes the waves oscillated across the globe. Then, suddenly, they stopped.
Scientists don’t know exactly what in the hell happened.
“I don’t think I’ve seen anything like it,” Göran Ekström, a Columbia University seismologist told National Geographic.
These waves were long-period and long-lasting when compared to the high-frequency seismic waves normally unleashed by an earthquake. Long-period seismic waves can be the petering out of an earthquake’s energy, but there was no earthquake preceding this strange rumbling of energy. Weirder still, most seismic events generate a big variety of frequencies of waves; this prolonged rumble was just the same monotone vibration for 20 long seconds.
So, what in the heck was it?
Magma, maybe. The waves originated near an island called Mayotte, which itself was born from volcanic activity. It’s possible that the waves were formed by the movement of great amounts of magma—and the resulting magnetic disturbances that can cause—moving and sliding around far below the seafloor. Sometimes, before violent volcanic activity, these kinds of long-period waves are produced, likely by magma chambers collapsing and expanding again.
But the strange uniformity is what’s freaking everybody out. “They’re too perfect to be nature,” said Helen Robinson, a volcanologist at the University of Glasgow.