Forces from Earth’s spin may spark earthquakes and volcanic eruptions at Mount Etna

Posted: December 27, 2019 by oldbrew in Cycles, Earthquakes, Geology, research, solar system dynamics, volcanos
Tags: ,

Mount Etna, Sicily


The article says: ‘Every 6.4 years, the axes line up and the wobble fades for a short time.’ This looks a lot like 5.4 Chandler wobbles (CW), so you would have 6.4 years minus 5.4 CW = 1 cycle, i.e. 32:27 ratio = 5 (32-27) cycles.
Much more analysis of this time period and related matters in this 2013 Talkshop post:
Ian Wilson: Solar System Timings Evolved Lunar Orbital Elements Linked to Earth’s Chandler Wobble
.

New research suggests forces pulling on Earth’s surface as the planet spins may trigger earthquakes and eruptions at volcanoes, reports Phys.org.

Seismic activity and bursts of magma near Italy’s Mount Etna increased when Earth’s rotational axis was furthest from its geographic axis, according to a new study comparing changes in Earth’s rotation to activity at the well-known Italian volcano.

Earth’s spin doesn’t always line up perfectly with its north and south poles. Instead, the geographic poles often twirl like a top around Earth’s rotational axis when viewed from space.

Every 6.4 years, the axes line up and the wobble fades for a short time—until the geographic poles move away from the spin axis and begin to spiral once again.

This phenomenon, called polar motion, is driven by changes in climate due to things like changing seasons, melting ice sheets or movement from tectonic plates.

As polar motion fluctuates, forces pulling the planet away from the sun tug at Earth’s crust, much like tides due to the gravitational pull from the sun and moon. The tide from polar motion causes the crust to deform over the span of seasons or years. This distortion is strongest at 45 degrees latitude, where the crust moves by about 1 centimeter (0.4 inches) per year.

Now, a new study published in AGU’s journal Geophysical Research Letters suggests that polar motion and subsequent shifts in Earth’s crust may increase volcanic activity.

“I find it quite exciting to know that while climate drives Earth’s spin, its rotation can also drive volcanoes and seismicity,” said Sébastien Lambert, a geophysicist at Paris Observatory in France and lead author of the study.

The new findings, however, don’t allow scientists to forecast volcanic activity. Although the study suggests earthquakes might be more common or volcanic eruptions may eject more lava when the distance between Earth’s geographic and rotational axes is at its peak, the timescale is too large for meaningful short-term forecasts, according to the authors.

But the results point to an interesting concept. “It’s the first time we’ve found this relationship in this direction from Earth’s rotation to volcanoes,” Lambert said. “It’s a small excitation process, but if you accumulate a small excitation over a long time it can lead to measurable consequences.”

Full article here.

Comments
  1. oldbrew says:

    Cyclic variability

    Around every 25-30 years Earth’s rotation slows temporarily by a few milliseconds per day, usually lasting around 5 years. 2017 was the fourth consecutive year that Earth’s rotation has slowed. The cause of this variability has not yet been determined.

    https://en.wikipedia.org/wiki/Earth's_rotation#Cyclic_variability
    – – –
    From a Forbes article: Nov 20, 2017

    Geophysicists are able to measure the rotational speed of Earth extremely precisely, calculating slight variations on the order of milliseconds. Now, scientists believe a slowdown of the Earth’s rotation is the link to an observed cyclical increase in earthquakes.

    To start, the research team of geologists analyzed every earthquake to occur since 1900 at a magnitude above 7.0. They were looking for trends in the occurrence of large earthquakes. What they found is that roughly every 32 years there was an uptick in the number of significant earthquakes worldwide. [bold added]

    https://www.forbes.com/sites/trevornace/2017/11/20/earths-rotation-is-mysteriously-slowing-down-experts-predict-uptick-in-2018-earthquakes/

    32 years = 27 Chandler wobbles (see post intro.)

  2. tallbloke says:

    Old ice seems to be building in the Arctic too.

  3. oldmanK says:

    It seems Earth dynamics are not at all understood. Look up also the Dzhanibekov effect

    http://arkadiusz-jadczyk.eu/blog/2017/01/dzhanibekov-effect-part-3/

    The youtube video shows the earth ref frame and space r f . What is the movement using the ecliptic plane as a r.f.? What if external torques from planetary alignments momentarily shift the space rf to a new position – the gyro behaviour?

    Since the Earth is not a solid object the surface wobbles with every imposed force from external sources. Earth’s crust moves. Some sections are known to move under the Coriolis force, resulting in rotation. This has been noticed by geologists, tectonic rotations (of micro plates), but the establishment is forcefully resisting any new ideas.

  4. oldbrew says:

    ‘Every 6.4 years, the axes line up and the wobble fades for a short time.’

    CW = ~1.18517 tropical years (TY). Beat period of CW and 1 TY (one Earth rotation):
    (CW * 1) / (CW – 1) = 1.18517 / 0.18517 = 6.4 TY.

    What they found is that roughly every 32 years there was an uptick in the number of significant earthquakes worldwide. – Forbes (see earlier comment)
    5 * 6.4 = 32 TY

    The Chandler wobble can have a ‘phase jump’ occasionally:
    https://arxiv.org/abs/0908.3732

  5. RoHa says:

    No, no. It’s man-made CO2 that causes earthquakes and volcanoes. Nothing to do with movement in the Earth’s crust.

  6. Bloke down the pub says:

    Oh Hell. For years I’ve been ridiculing alarmist claims that CO2 caused increased vulcanicity and now they’ve got a viable link to throw back.

  7. oldbrew says:

    oldmanK says: Since the Earth is not a solid object the surface wobbles with every imposed force from external sources. Earth’s crust moves. Some sections are known to move under the Coriolis force, resulting in rotation. This has been noticed by geologists, tectonic rotations (of micro plates), but the establishment is forcefully resisting any new ideas.
    – – –
    The thing is, the Coriolis ‘force’ is fictitious…

    In physics, the Coriolis force is an inertial or fictitious force[1] that acts on objects that are in motion within a frame of reference that rotates with respect to an inertial frame.
    https://en.wikipedia.org/wiki/Coriolis_force

  8. oldmanK says:

    Can Wiki be trusted? In another situation wiki acted as a ‘gate-keeper’. So no.

    Re Coriolis see http://www.lextalus.com/pdf/The%20Coriolis%20Effect.pdf Do not miss this footnote “Also for this reason, and not only because the force is inertial, the Coriolis force does not do any work on the body, i.e. it does not change its speed (kinetic energy), only the direction of its motion. The statement that the Coriolis force “does not do any work” should not be misunderstood that it “doesn’t do anything”.”.
    See also point 8.

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