An enigmatic faint tremor keeps rocking our planet every 26 seconds, with scientists remaining none the wiser about its origins, according to Discover magazine.
First documented in the Sixties by a researcher named Jack Oliver, the microseism, or planetary heartbeat as it came to be called, was then investigated closer in 1980 by a geologist with the US Geological Survey, Gary Holcomb. However, as Discover says, their work would “mostly be lost to time”.
"Jack didn’t have the resources in 1962 that we had in 2005 - he didn’t have digital seismometers, he was dealing with paper records," said Mike Ritzwoller, a seismologist at the University of Colorado, Boulder, "whose team would independently come across the strange pulse some decades later".
Though Oliver managed to track the pulse's origins to somewhere "in the southern or equatorial Atlantic Ocean", decades later, Garrett Euler, a graduate student at seismologist Doug Wiens’ lab at Washington University in St Louis, has managed to narrow it down further, to "a part of the Gulf of Guinea called the Bight of Bonny".
However, whereas Euler, who presented his findings at the Seismological Society of America conference in 2013, postulated that the pulse is caused by ocean waves hitting the coast, a team led by Yingjie Xia from the Institute of Geodesy and Geophysics in Wuhan, China proposed instead that the tremors are most likely related to volcanoes, since a volcano on the island of Sao Tome in the Bight of Bonny appears to be fairly close to the pulse's "point of origin".
"We’re still waiting for the fundamental explanation of the cause of this phenomenon," Ritzwoller said. "I think the point [of all this] is there are very interesting, fundamental phenomena on Earth that are known to exist out there and remain secret."