Hear that? The so-called mysterious hums are heard around the world by many people, yet scientists and government officials don’t seem to be able to identify them nor explain why some pick them up their frequencies while others don’t. Anyone who’s ever been in a room where a woman is giving birth knows that none of the sounds heard during this momentous event are anywhere close to a hum. That’s why you may be shocked to learn that a mysterious hum picked up two years ago around the world was caused by a birthing event … a BIG birthing event – the birth of a huge underwater volcano deep in the Indian Ocean. Did you hear it?
“First, it rang at just a single ultra-low frequency, like a well-tuned bell. Seismic waves usually involve lots of different frequencies. Second, the wave emerged and circled the planet without the usual signs of an earthquake; no one in the area felt any shaking, and the "p-waves" and "s-waves" associated with the hum, the sort of waves that you actually feel during an earthquake, were so faint as to be nearly undetectable.”
In November 2018, Live Science reported on a mysterious hum at an ultra-low frequency that slowly made its way around the world. The frequency was so low that the best ears for picking it up were seismographs. In fact, seismologists had been picking up unusual hums since May 2018 from near the island of Mayotte in the Comoros archipelago of the Indian Ocean between Africa and Madagascar. However, according to the press release announcing the study of these hums, the ones (there were over 400) on November 11, 2018, were like none they had ever picked up before. And yet … Live Science reported that they couldn’t find the source.
“Perhaps a "slow earthquake" struck the area, the sort that doesn't cause much intense shaking because it occurs over a much longer period of time. Perhaps a bubble of magma squeezed past below the surface, or sloshed around in a big hole in the crust in a way that interacted with the local geology to produce the resonant ringing. Researchers even speculated about a meteor strike, though that seems unlikely. For now, the exact cause remains a mystery.”
No evidence of any such events near Mayotte were found. However, in early 2019, a French
oceanographic expedition discovered a huge new underwater volcano near Mayotte measuring about 3.1 miles (5 km) in length and almost a half mile (0.8 km) high. Despite this size, no one noticed the underwater eruption because it occurred at a depth of 3 km (1.87 miles). Could this volcano be linked to the mysterious hums?
Enter Simone Cesca, a seismologist at the GFZ German Research Centre for Geosciences and lead author of the connect-the-humming-dots study in the current edition of the journal Nature Geoscience. The press release describes how Cesca and an international team of scientists suspected the earlier hums, the big burst in November 2019 and the 2019 underwater volcano may be connected, but the area is not monitored by any seismic network. Lacking solid data, Cesca spent a year looking for unusual seismic recordings far from Mayotte during the same timeframe. Since you’re already reading about the discovery, there’s no need for a spoiler alert – they found them.
“The team identified different activity phases within the sequence of events from May 2018 to today. The initial swarm phase indicated a rapid upward movement of magma from a deep mantle reservoir more than 30 kilometres below the Earth's surface. Once an open channel had formed from the Earth's mantle to the seabed, the magma began to flow unhindered and form a new underwater volcano.”
At a depth of 30 km (18.7 miles), that’s the deepest magma reservoir ever recorded. While the volcano continues to show no visible signs of its existence to the residents of Mayotte (known as the 'seahorse island' due to its unusual shape; population about 270,000; under the jurisdiction of France), the reservoir may collapse again, causing earthquakes whose hums could do more than just move seismograph needles.
There was no gender reveal party, so send your generic ‘Congratulations on your new baby’ cards to Mother Earth, the biggest and best single mom around.