Seismic ‘Hums’ Detected Around World Traced Back To Rare Birth Of Underwater Volcano
From The Independent by Andy Gregory
A series of low “seismic hums” detected across the world have been traced back to the birth of an underwater volcano, bringing an extraordinary conclusion to a mystery that baffled the scientific community for months.
On 11 November 2018, a series of more than 400 bizarre pulses lasting up to 40 minutes in length emanated from just off the coast of Mayotte, a small Indian Ocean tucked between Madagascar and Mozambique.While nobody is thought to have felt the tremors, they set off sensors in several East African nations, before reverberating to locations as diverse and far afield as Chile, Hawaii, Canada and some 11,000 miles away in New Zealand.
The impeccably neat structure of the slow-moving, low-frequency waveforms typically associated with large earthquakes – which are more chaotic – also intrigued scientists.
“They’re too nice. They’re too perfect to be nature,” joked Helen Robinson, a volcanology researcher at the University of Glasgow. In chasing the source of the strangely uniform pulses, a team of geologists in Germany have painstakingly reconstructed the collapse of what is believed to be one of the largest magma reservoirs in the earth’s upper mantle.
The collapse occurred as a result of the birth of a huge volcano on the sea floor, which the team say is the first time scientists have properly observed such an event.
The volcano entered the world several months before the seismic hums were detected, to the rumble of thousands of “seemingly tectonic” earthquakes – including one large magnitude 5.8 event – near Mayotte, an area relatively bereft of seismic activity for some 4,000 years previously.
Then came the mysterious pulses. Scientists now calculate that with their arrival, Mayotte – which has a population of more than 250,000 people – also began to sink and shift eastwards, moving almost 20cm to date.
Amid various fantastical suggestions for what could be responsible, the idea that the pulses could be linked to volcanic activity began to gain traction. Sure enough, in May 2019 a group of French researchers discovered the existence of a new underwater volcano near Mayotte.
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