Something very unusual rumbled across the planet on November 11th, 2018, and scientists say they have never seen anything like it. For about 20 minutes, instruments measured unusual seismic activity more than 10,000 miles away from where it originated, but not a single human felt them.
Seismic waves fromMayotte, an island between Africa and Madagascar traveled around the globe. They were recorded all over Africa and as far away as New Zealand, Canada, Chile, and Hawaii, approximately 11,000 miles away.
No humans felt these bizarre seismic waves, but the strange signal was noticed on the US Geological Survey’s (USGS) seismograph displays:
This is a most odd and unusual seismic signal.
— ******* Pax (@matarikipax) November 11, 2018
Recorded at Kilima Mbogo, Kenya ...#earthquakehttps://t.co/GIHQWSXShd pic.twitter.com/FTSpNVTJ9B
Matarikipax also tweeted waves detected in Ethiopia, Zambia, Spain, and New Zealand. Thanks to the social media savvy earthquake enthusiast, researchers around the globe took note.
The unusual seismic waves that travelled around the world on November 11th were well-recorded across Canada. The waves (unknown origin at this time) originated near Mayotte (between Madagascar and East Africa). Interesting discussion here:https://t.co/4CFwBhLv8j pic.twitter.com/DMsOm4O5hS
— John Cassidy (@earthquakeguy) November 13, 2018
According to the French Geological Survey team (BRGM) working at the Geology Laboratory of the Ecole Normale Supérieure in Paris, on November 11th, 2018 “=an atypical very low-frequency signal was detected by the international networks.” Low-frequency signals of this kind are characteristic of volcanic phenomena.
As Göran Ekström, Columbia University seismologist reported to National Geographic that:
“I don’t think I’ve seen anything like it.”
Typically, an earthquake releases its energy in one big burst, leading to the presence of several different kinds of waves – surface waves, S-waves, and P-waves.
The first type is a P-wave or rather a compressional wave (fastest of the three types). They shake the ground back and forth. The next is a shear wave (S-wave). S-waves translate into massive jolts and strong side-to-side shaking. Both P-waves and S-waves have high frequencies.
The third type is a surface wave. Surface waves occur near the planet’s surface and are felt like a rolling motion. Strong earthquakes can cause surface waves that travel around the earth multiple times.
Despite the absence of a massive earthquake near Mayotte on November 11th, low-frequency waves similar to surface waves were measured, yet they were unlike any previously estimated surface waves, as they were uniform and clean.
As the French Geological Survey reports, Mayotte has seen some hundred seismic events since May 2018. When multiple seismic events happen in a specific zone over a short period, it is often referred to as an “earthquake swarm.” Before the swarm events beginning in May, the earthquakes on and around Mayotte were of the typical “main shock, followed by smaller after-shocks” type. The appearance of the particular event, neither earthquake nor swarm, took researchers by surprise.
About every half a minute the ground moved up and down while the waves rolled. As John Cassidy, an earthquake seismologist with Natural Resources Canada told Global News, there was a “very slow shaking.”
According to the Mind Unleashed, if there's indeed volcanic activity occurring near Mayotte, it'd be the first in more than 4,000 years. Since July 2018, GPS stations on the island have tracked Mayotte moving 1.2 inches south and 2.4 inches east as reported by the Institut National de L’information Géographique et Forestière.
Helen Robinson, curring working on a Ph.D. in applied volcanology at the University of Glasgow, filtered out the low-frequency waves and found what appeared to be P- and S- waves resulting from tiny tremors at the very beginning of the event. However, even those weren’t normal.
All we know is that nobody felt the mysterious seismic waves and nobody knows what they mean. Current theories suggest a rhythmic motion occurred in a magma chamber thanks to some subsurface shift or chamber collapse. However, little evidence exists. Rest assured, though, BRGM is on the case and plans to complete surveys to see if there was a submarine volcanic eruption.
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