On 11/11 A 17 second signal went around the world
Strange waves rippled around the world, and nobody knows why
On the morning of November 11, just before 9:30 UT, a mysterious rumble rolled around the world.
The seismic waves began roughly 15 miles off the shores of Mayotte, a French island sandwiched between Africa and the northern tip of Madagascar. The waves buzzed across Africa, ringing sensors in Zambia, Kenya, and Ethiopia. They traversed vast oceans, humming across Chile, New Zealand, Canada, and even Hawaii nearly 11,000 miles away.
However, there was no big earthquake kicking off the recent slow waves. Adding to the weirdness, Mayotte's mystery waves are what scientists call monochromatic. Most earthquakes send out waves with a slew of different frequencies, but Mayotte's signal was a clean zigzag dominated by one type of wave that took a steady 17 seconds to repeat.
"steady 17 seconds "
https://www.nationalgeographic.com/science/2018/11/strange-earthquake-waves-rippled-around-world-earth-geology/?cmpid=org=ngp::mc=social::src=twitter::cmp=editorial::add=tw20181128science-earthquake::rid=&sf203143149=1