Earth's metal core acts like a giant magnet that emanates a magnetic field with two poles, north and south.
In addition, every several hundred thousand years, Earth's magnetic field reverses - a compass that would have pointed north would instead aim south.
Full reversals of the magnetic field usually take millennia to finish, based on those frozen rock records. Scientists analyzed data in sediment from the floor of the Black Sea and compared it with other data from the North Atlantic, the Southeast Pacific and around Hawaii. Earth's magnetic field stayed reversed for only 440 years, during which time it was just one-quarter as strong as it is today. The brevity of this flip overall suggests "it might represent a so-called aborted reversal," Nowaczyk said. Earth's magnetic field helps protect the planet from energetic particles streaking out from deep space and the sun. Such radiation poses a particular threat in our modern world, so understanding these reversals is helpful to better understand the threats from space. First thing that I thought of as reading this article was the Hopi Indians and their prophesy. From warmest December on record to blizzards, wild winter sets records across the northeastern U.S. To a first approximation, the Earth's magnetic field resembles that of an enormous bar magnet. Several features of the Earth's field vary in a predictable way across the surface of the globe and might, in principle, be used in assessing geographic position. A second geomagnetic parameter that varies across the surface of the Earth is the strength or intensity of the field. Inclination angle: The angle at which the magnetic field lines intersect the surface of the earth. At the latest magnetic personalities meeting we looked at a paper by Ron Shaar and Lisa Tauxe named ‘Thellier GUI: An integrated tool for analysing palaeointensity data from Thellier type experiments’ published in Geochemistry, Geophysics, Geosystems.
As with many disciplines in science there is debate over the best methods of analysing data. The Thellier GUI integrated tool for palaeointensity analysis is designed to isolate the criteria of most importance during analyses at the specimen and sample stages.
We unanimously agree there should be more uniformity in this field and hopefully this tool will go some way towards this.
Last week, Megan and I were away in Oxford taking part in a National Environmental Research Council (NERC) sponsored young entrepreneurs competition. Steve approached The University Graduate School, Management School and Technology Transfer Services, all of whom have provided us with lots of help in preparing for the competition.
Having chosen our idea we had to formulate it into a viable, appealing and realistic business proposition.
The judges verdict was announced at 3pm on Friday afternoon, to a room packed full of expectant participants and mentors.
SWARM is a long awaited ESA satelite mission to measure the geomagnetic field using magnetometers deployed on three separate but identical satelites. The most interesting talk for me personally was given by Elina Aidona from the Aristole University of Thessaloniki, Greece who had conducted a study on archaeological ovens and found that the errors on the archaeomagnetically assigned age was lower than the errors on the thermoluminescence dates.  This is highly unusual and was a very interesting case study. All in all, it was a very interesting paper to study and its always good to sit in the sunshine and discuss a paper that tackles a problem in an interesting way! The latest in our paper discussions took us away from our usual  territory- and out to Saturn.
The results they find agree with what was previously found – that Saturn’s field is highly axisymmetric, with most of the magnetic flux confined to polar regions, and higher degrees of the field are relatively small contributions to the overall measured field – hence not being seen on some more distant orbits of the satellite.
I chose this paper because of some intriguing results I’ve had working on my Archean aged samples. It has been suggested, since the late 1950s, that given the right conditions, some oceanic basalts can carry a self-reversed chemical remanent magnetisation (CRM). In oceanic basalts, oxidation occurs by the removal of iron due to interaction with sea water or sea water bearing fluids. We speculated that the tiles supporting the floor of the bath (the hypocaust) may have had two magnetic components – one from their original firing when they were created as tiles and a second lower temperature component from their proximity to the fire (the praefurnium or furnace room) that was heating the bath area.  We discussed whether there might be a temperature gradient with distance from the praefurnium. With the overall general aim of providing the archaeologists with potential dates depending on the magnetic signature recorded by the samples, over 200 individual samples were taken. So when I returned to France in April of this year to begin the measuring I was faced with a lot of samples to measure.  I had 6 weeks in which to do it but initially I wasn’t sure it would be enough time! In the first 2 weeks of my trip to the Rennes 1 geomagnetism laboratory, I was able to carry out two experiments.  The first was a palaeointensity experiment on 45 cores which involved repeated heating steps to increasing temperature. In addition to the palaeointensity experiment, I also conducted a demagnetisation experiment to see if we could find evidence of two heating components in the samples from the hypocaust.   When the demagnetisation experiment was completed, I carried out an anisotropy experiment to check that the samples weren’t significantly anisotropic as this can affect their ability to record magnetisation. In this picture I am preparing to measure the positive y component of the magnetic vector in the samples as part of the anisotropy experiment. In the next four weeks, I intend to carry out at least two more palaeointensity experiments and look at tiles which lined the drains from the baths.  If all goes well, I should have time at the end to discuss my results with Philippe and others at Rennes 1.
Its really good to visit another lab and carry out experiments because invariably they have different instruments to those at Liverpool, different techniques are favoured and its always good to have fresh ears to discuss your work with!  I am finding it a very rewarding experience and sometimes I even think my French might be improving! Research suggests that the Moon once had an active magnetic field, much like Earth’s magnetic field.


Earth’s magnetic field is generated by what’s called a dynamo, driven by heat convection causing fluid motion of the conducting liquid iron alloy in the outer core.
A few alternative power sources have been considered, including a precession driven dynamo caused by the Moon’s core and its mantle rotating around slightly different axes. The source of the Moon’s dynamo and when or why it decayed remains a mystery, but by learning more about it we may also improve our understanding of Earth’s magnetic field. The paper we discussed in the latest meeting of Magnetic Personalities and which motivated the piece below was Anzellini et al. They estimate the temperature of the boundary between the inner and outer core to be around 6,000 degrees Celsius based on extrapolations of the melting temperature of iron at extreme pressures and temperatures. 15 in the journal Earth and Planetary Science Letters,could shed light on how and why magnetic field reversals happen, and how they leave Earth vulnerable to solar and space radiation, the study scientists said. These two magnetic poles very roughly match where the planet's geographic north and south poles lie, which mark the axis on which Earth spins.
These flips are captured by magnetically sensitive minerals in cooling lava that are literally set in stone pointing to where the poles were at that particular moment in Earth's history. However, scientists now find that 41,000 years ago, shortly after modern humans first entered Europe, the magnetic poles flipped and flipped again in less than a millennium.
Surprisingly, they found the Earth's magnetic field took about 200 years to flip, during which time it was just one-twentieth as strong as it is today.
The magnetic poles then flipped back to approximately where they were before over the course of about 270 years. During the Laschamp reversal, Earth was significantly more vulnerable to radiation from space, judging by higher levels of radioactive beryllium seen in ice samples from Greenland, Nowaczyk said. If this is actual fact, if you apply the "shift" to their prophesy of the Earths reversal and the emergence of human kind into cycles "worlds", it draws somewhat of an comparison. I chose this paper as it has direct relevance to the laboratory at Liverpool where we carry out much palaeointensity research.
Ideally there would be a format giving rise to objective results that could be reproducible and correlated between laboratories. Uniformity of methods and analysis would greatly benefit our models of magnetic field behaviour where correlation of worldwide studies is paramount. One of our fellow PhD students in the school, Steve Hicks, approached us towards the end of the summer, to see if we fancied having a go at the competition. During our first meeting with them, we ‘pitched’ our three ideas (note how I am already slipping into my newly acquired business and commercial vocabulary). I got on with really understanding the science behind the idea and explained to the team how the world of environmental consultancy worked (as I worked as a consultant before I started my PhD).
The first two days were dedicated to learning more about how to set-up your own business, receiving help and support from a wide range of mentors and hearing from people who have actually gone on to set up their own company (some as a result of participating in the competition). Team TERGEO are super excited to announce that we made it through the regional finals and are now on our way to Grand Final in London on 2nd December!
I chose this paper as I thought it would be interesting to discuss a paper that approaches the problem of geomagnetic field reconstruction in a very different way.
Cao et al’s paper Saturn’s high degree magnetic moments: Evidence for a unique planetary dynamo looks at modelling the magnetic field of Saturn, which is very different to the field of the Earth. They also suggest a similarity to certain types of dynamo models – such as spherical Couette dynamos, where the dynamo is driven by differential rotation between outer and inner layers of a shell. Kelly is a PhD student in the geomagnetism research group at the Department of Earth, Ocean and Ecological Sciences at the Univeristy of Liverpool. I was keen to hear what the lab had to say about the paper above, but also about my results and self-reversals in general, as they are pretty controversial due to being quite poorly understood.
Research by Verhoogen (1956) suggested that self-reversals could occur in titanomagnetites by ionic reordering during low-temperature oxidation. Self-reversals occur at a critical degree of oxidation when it is possible for cation vacancies created at tetrahedral sites (A magnetic sublattice) to migrate into the octahedral sublattice, via diffusion. In addition, work by Schult (1968, 1971) shows that ionic reordering should produce N or Q-type thermomagentic behaviour.
The work presented in the paper suggests that the very high oxidation states and high Ti contents are required to produce a true self-reversals negates the possibility of it being a common occurrence in oceanic basalts. On the left I am using a magnetic compass to measure the orientation of the sample with respect to magnetic North.
Evidence comes from palaeomagnetic measurements made on lunar rocks collected during the Apollo missions. If the boundary between the core and the mantle is not quite spherical, their relative motion could stir up the liquid outer core enough to generate a magnetic field. Extrapolating from this, the top of the core would be just under 4,000°C and the heat flow to the base of the 1,000°C cooler mantle some 10 TW. The flip-flop overall is known as the Laschamp event, after the area in France where evidence of it was first discoveredin the 1960s. These magnets can, in principle, cancel each other out, causing the magnetic field overall to weaken or flip. I'm not going into it, but science, religion, & prophecies all point to the same things regardless of what culture, race, color, heritage, religion, etc. New statistics include FRAC, a fraction statistic and a new scatter statistic amalgamating all scatter including pTRM and tail checks called SCAT, and finally GAP-MAX an upper limit for the gap between data points in an Arai plot. We both agreed to do it as it was an opportunity to learn about the business world, which we knew little about.  Lidong Bie decided to join our team, and so we could get to work!


Eventually, we managed to narrow it down to three ideas: using pea straw for the remediation of contaminated land, developing a service to monitor seismicity associated with fracking activities and the monitoring of air quality by measuring magnetic particles on tree leaves.
The final day of the workshop saw all the teams go up against each other in front of a panel of ‘investors’.
Parts of the magnetic field have been measured by Pioneer 11, and both Voyager missions, and more recently, Saturn has been visited by the Cassini mission, which also recorded magnetic data, and essentially confirmed what was already known.
This is a very different type of dynamo to the Earth, with its convection driven dynamo – and indeed may not even be physically possible for Saturn! The authors suggest that self-reversal is indicative of unusual ocean floor conditions such as extreme fluid flow and iron removal. On the right, Valerie is using a sun compass to measure the location with respect to the sun.
Studies have shown, however, that due to the smaller size of the Moon, compared to Earth, a similar heat convection driven dynamo would only have been able to persist up to about 4.1 billion years ago. Another possible explanation relates to large-scale meteorite impacts capable of temporarily changing the relative motion of the mantle with respect to the core.
For comparison, this transfer of energy is just under the 13TW present rate of energy “consumption” (energy is never consumed, only transferred and transformed) by all of human civilisation.
If we have proved that the Earth reverses, but don't know exactly what kind of effect if will have on life, land mass, oceans, animals, plants, etc.. A plethora of Thellier style palaeointensity methods and analysis make it difficult to correlate across studies.
Sample level palaeointensity values are then calculated using an optimised standard deviation statistic and simple and parametric bootstrap methods. Work is also underway to integrate the Liverpool Palaeomagnetic Database with the MagIC database to encourage the standardisation of data format and consistency of analyses.
In the competition, teams of early-career researchers (PhD students and post-dcos) attend a three-day workshop where they are given training and guidance on innovation and how to commercialise research.
Two of our ideas were based on already published research, which you can read all about here and here.  As it is a business competition, we had to assign ourselves roles within the management of our fictitious company.
Lidong had the arduous task of getting to grips with endless financial spread sheets and costing up both our site works and overall business running costs. We had to deliver 15 minute business presentations, to compete for the judge’s investment in our company. Analysis of the data from Pioneer and Voyager(s) and modelling of low spherical harmonic degrees (g01, g02 and g03) show Saturn’s field to be highly axisymmetric (i.e. In this case, the different rotations could be due to a transition in the phase of helium (such as the gaseous atmosphere ‘raining’ liquid helium at pressure), a metallic layer, or the solid core of the planet. However, it was not until the research published in Doubrovine & Tarduno, 2004, that a clear example of this process was identified and so, little research into self-reversals was conducted during the 1990s.
It allows single domain grains (and perhaps also pseudosingle domain grains) that carry a CRM by titanomagnetite to transform into an antipodal CRM. Recent results suggesting an active dynamo well beyond this time would have required a very different power source. The main issues highlighted by the authors are the subjective nature of manual palaeointensity analyses, that it is very time consuming and that unless the raw data is published the results are not reproducible.
At the end of the three-day workshop, teams present and pitch their ideas for an imaginary environmental start-up company in competition with each other.
Steve took on the role of CEO, Lidong became our finance man, Megan is in charge of marketing, whilst I am our research and development officer (i.e, I’m in charge of the science).
This was certainly the part of the paper that provoked most discussion amongst us – and several sci-fi type visualisations of what helium rain might look like! I recommend you take a look at the two papers if you want to understand this process more fully, they’ve got some good formulas which might help! This means that the Moon’s magnetic field may have been present at least 160 million years longer than previously thought. The last known impact large enough to produce such an effect (producing an impact crater diameter of around 300 km) is dated to 3.7 billion years ago.
The winning teams from each workshop are invited to a final where they compete for a prize of ?2500. Intellectual property and how you can protect ideas, products and know how is fascinating and at the same time, extremely complex. Some of the ideas pitched by other teams were incredibly interesting: tents with built in solar panels, an app that worked out what the most eco-friendly products available in a supermarket are, a chip that monitors your UV exposure, a  pressure driven turbine that generates power from the main water supply and a solar panel with a kick!
Such an impact-driven dynamo therefore seems a rather unlikely source for the magnetic field recorded in lava rocks on the Moon 160 million years later. Everything, anything, and nothing are all possibilities, we all just need to wake up and see it because things are pretty clear that the Earth is changing rapidly and faster than ever recorded.
There has also been very little change in the field measured between the Voyager missions and Cassini’s arrival. The magnetic moments of the lower spherical harmonic degrees having being well modelled with the available data, in this paper the authors try to model higher degrees, g04 and g05 with the new data from Cassini.




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Rubric: Canada Emergency Preparedness



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