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Strange Seismic Waves that Rippled Around World Leave Scientists Bewildered

posted by martyb on Wednesday December 05 2018, @12:55AM   Printer-friendly
from the I'm-all-shook-up dept.

An Anonymous Coward writes:

Just before 9.30am on Sunday 11 November, a series of unusual seismic pulses rippled around the world almost undetected.

The waves rang for over 20 minutes, emanating about 15 miles off the shores of Mayotte - a tiny island in the Indian Ocean between Madagascar and Africa.

From here, they reverberated across Africa, setting off geological sensors in Zambia, Kenya, and Ethiopia.

They crossed the Atlantic, and were picked up in Chile, New Zealand, Canada, and even Hawaii nearly 11,000 miles away, the National Geographic reports.

Despite their huge range, the waves were apparently not felt by anybody. However, one person monitoring the US Geological Survey's live stream of seismogram displays did notice the unusual waveform and posted it to Twitter, sparking the interest of other geologists and earthquake enthusiasts.

[...] The bizarre waveform is what scientists call "monochromatic". Earthquakes normally produce waves of so many different frequencies, the wave readings appear more jumbled.

But the mystery waveform from Mayotte was a crisp zigzag, which repeated after steady 17-second intervals.

"They're too nice. They're too perfect to be nature," joked the University of Glasgow's Helen Robinson, who is study[ing] for a PhD in applied volcanology.

https://www.independent.co.uk/news/world/earthquake-seismic-waves-mayotte-madagascar-volcanic-activity-science-a8659236.html

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  • (Score: 1) by khallow on Thursday December 06 2018, @03:21AM (4 children)

    by khallow (3766) Subscriber Badge on Thursday December 06 2018, @03:21AM (#770458) Journal
    On that matter, we have this from the National Geographic story:

    Finally, chugging along at the end come slow, long-period surface waves, which are similar to the strange signals that rolled out from Mayotte. For intense earthquakes, these surface waves can zip around the planet multiple times, ringing Earth like a bell, Hicks says.

    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.

    Surface waves are indicative of near surface earthquakes.

  • (Score: 2) by c0lo on Thursday December 06 2018, @03:41AM (3 children)

    by c0lo (156) Subscriber Badge on Thursday December 06 2018, @03:41AM (#770467) Journal

    these surface waves can zip around the planet multiple times, ringing Earth like a bell, Hicks says.
    However, there was no big earthquake kicking off the recent slow waves....

    vs my:

    The hypothesis of a 'reconfiguration' of the crust as a whole may explain the large range of this one and the regularity of the wave... this may be a resonating wave ringing the "globular bell"of the Earth's crust.

    You know? Like a PET bottle one has stepped on and which slowly gets to a configuration closer to the non-deformed shape, occasionally popping when a crease gets smoother.

    Still a hypothesis (which I don't have time or resources to investigate).

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford

    • (Score: 1) by khallow on Thursday December 06 2018, @07:34PM (2 children)

      by khallow (3766) Subscriber Badge on Thursday December 06 2018, @07:34PM (#770803) Journal
      Let us also note that tidal forces create larger distortions as well.

      • (Score: 2) by c0lo on Friday December 07 2018, @01:45AM (1 child)

        by c0lo (156) Subscriber Badge on Friday December 07 2018, @01:45AM (#770982) Journal

        Let us note that those distortions are present with or without post glacial rebound.
        Expecting the rebound to have no detectable effect on global scale is unreasonable.

        --
        https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford

        • (Score: 1) by khallow on Friday December 07 2018, @07:00AM

          by khallow (3766) Subscriber Badge on Friday December 07 2018, @07:00AM (#771059) Journal

          Let us note that those distortions are present with or without post glacial rebound.

          Those far greater distortions are present. And this weird thing doesn't happen twice a day.