Earth Magnetism and Rock Physics

Imaggeo on Mondays: Chilean relics of Earth’s past

Imaggeo on Mondays: Chilean relics of Earth’s past

As Earth’s environment changes, it leaves behind clues used by scientists to paint portraits of the past: scorched timber, water-weathered shores, hardened lava flows. Chile’s Conguillío National Park is teeming with these kind of geologic artifacts; some are only a few years old while others have existed for more than 30 million years. The photographer Anita Di Chiara, a researcher at Lancaster University in the UK, describes how she analyses ancient magnetic field records to learn about Earth’s changing crust.

Llaima Volcano, within the Conguillío National Park in Chile, is in the background of this image with its typical double-hump shape. The lake is called Lago Verde and the trunks sticking out are likely remnants from one of the many seasonal fires that have left their mark on this area (the last one was in 2015).

The lake sits on pyroclastic deposits that erupted from the Llaima Volcano. On these deposits, on the side of the lake, you can even track the geologic record of seasonal lake level changes, as the layers shown here mark the old (higher) level of the lake during heavy winter rains.

The lake also overlaps the Liquiñe-Ofqui Fault, which runs about 1000 kilometers along the North Patagonian Andes. The fault has been responsible for both volcanic and seismic activity in the region since the Oligocene (around 30 million years ago).

I was there as field assistant for Catalina Hernandez Moreno, a geoscientist at Italy’s National Institute of Geophysics and Volcanology, studying ancient magnetic field records imprinted on rocks. We examined the rocks’ magnetised minerals (aligned like a compass needle to the north pole) as a way to measure how fragmented blocks of the Earth’s crust have rotated over time along the fault.

From this fieldwork we were able to examine palaeomagnetic rotation patterns from 98 Oligocene-Pleistocene volcanic sites. Even more, we concluded that the lava flows from the Llaima Volcano’s 1958 eruption would be a suitable site for studying the evolution of the South Atlantic Anomaly, an area within the South Atlantic Ocean where the Earth’s magnetic field is mysteriously weaker than expected.

By Anita Di Chiara, a research technician at the Lancaster Environment Centre in the UK 


Hernandez-Moreno, C., Speranza, F., & Di Chiara, A.: Understanding kinematics of intra-arc transcurrent deformation: Paleomagnetic evidence from the Liquiñe-Ofqui fault zone (Chile, 38-41°S), Tectonics,, 2014.

Hernandez-Moreno, C., Speranza, F., & Di Chiara, A.: Paleomagnetic rotation pattern of the southern Chile fore-arc sliver (38°S-42°S): A new tool to evaluate plate locking along subduction zones. Journal of Geophysical Research: Solid Earth, 121(2),, 2016.

Di Chiara, A., Moncinhatto, T., Hernandez Moreno, C., Pavón-Carrasco, F. J., & Trindade, R. I. F.: Paleomagnetic study of an historical lava flow from the Llaima volcano, Chile. Journal of South American Earth Sciences, 77,, 2017.


Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submittheir photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at

GeoTalk: Stephanie Zihms, Early Career Scientist Representative

GeoTalk: Stephanie Zihms, Early Career Scientist Representative

In addition to the usual GeoTalk interviews, where we highlight the work and achievements of early career researchers, this month we’ll also introduce one of the Division early career scientist representatives (ECS). They are responsible for ensuring that the voice of EGU ECS membership is heard. From organising short courses during the General Assembly, through to running and attending regular ECS representative meetings, their tasks in this role are varied. Their role is entirely voluntary and they are all active members of their research community, so we’ll also be touching on their scientific work during the interview.

Today we are talking to Stephanie Zihms, ECS representative for the Earth Magnetism & Rock Physics (EMRP) Division and the incoming Union-level ECS representative. Interested in getting involved with EGU and its activities for early career scientists? Consider applying for one of the vacant representative positions

Before we get stuck in, could you introduce yourself and tell us a little more about yourself and your career?

Where to start, I’m originally from Germany but moved to the UK in 2005 for an year and ended up staying. I have had a varied career and would probably call myself a multidisciplinary geoscientist.

After graduating with a bachelor’s degree in Earth Science from the University of Glasgow (2007), I worked for a geotechnical drilling company in Scotland as a geologist. However, I still had a drive to further my education, so following the economic downturn in 2008-2009, I started my PhD in Civil & Environmental Engineering from University of Strathclyde. After my PhD, I left academia again to work for the British Geological Survey, where for 14 months I studied the impact of heat on bentonite for radioactive waste disposal. This wasn’t quite the right fit for me, and I left to go back to academia for a postdoc.

In January 2015 I joined Heriot-Watt University, originally for a postdoc position looking at CO2 bubble behaviour in flow conditions (definitely a ‘tide me over’ position). After 4 months I joined the Institute of Petroleum Engineering for a geomechanics postdoc – finally working with rocks again. Now I have a postdoc in the Heriot-Watt University Lyell Centre studying fracture flow. This postdoc is great since it combines my experience from my previous postdoc and my time at the British Geological Survey.

Outside of work I love running, and I am currently training for a half marathon. I started running again after I was diagnosed with multiple sclerosis to better manage my mental health and increase my overall fitness.

Although we touch upon it in the introduction of this post: could you tell us what your role as ECS representative has involved and explain your new role as the Union-level ECS representative?

I was the first ECS representative for the EMRP Division and was kind of thrown in the deep end, but it was great to have some freedom to shape the role within the division. The biggest part is being the link between the division president and officers and the ECS community. I attend online meetings where all the ECS representatives exchange ideas, discuss issues and find solutions or support. For EMRP, I set up the division Twitter account and recruited some other ECS to help me run a Facebook page. Most divisions have a small team, which is a great way to get involved. At the 2017 General Assembly I organised an ECS dinner (open to all EMRP scientists) which went really well with over 40 scientists attending. We are planning to host a similar event at this year’s General Assembly.

As the Union-level ECS representative, I will be the link between the Union and the ECS via the division representatives. This is a very important role since it will be my job to represent the work the ECS representatives have done and present any changes the ECS representatives would like to see. Of course, I will have help from the new incoming Union-level representative Raffaele Albano, the EGU Outreach Committee, and you as the communication officer*.

I’m looking forward to working with you! So, why did you put yourself forward for these positions?

I volunteered for both roles because I think it’s important for ECS to have a say, get involved and have proper representation. We are the future of research and our voice should be counted. I am a big believer in peer-support and the ECS representatives provide this in a very positive way. It is also a great opportunity to get to know the insides of the EGU better and how it is all organised.

What can your ECS division members expect from the Earth Magnetism & Rock Physics Division in the 2018 General Assembly?

For the 2018 General Assembly we are planning an ECS dinner again (check your emails or our Facebook page for more information and updates). We will have representatives at the ECS Corner at the ice-breaker on Sunday evening, and I hope EMRP ECS will stop by to say ‘Hi!’ In addition to the official ‘Meet EGU’ booth with our division president, I’m planning a Meet & Greet in the ECS Lounge as well to provide another opportunity for ECS to introduce themselves, ask questions or get advice.

We are not planning any EMRP specific short courses this year but would be happy to help organise some for 2019. The short course programme at the EGU General Assembly is always great, and I highly encourage everyone to have a look at what’s offered.

Our division ECS team has four members, with one stepping up as the next EMRP division ECS representative. If anyone is interested in helping out but not sure about becoming a representative, consider joining your division ECS team. They will be grateful for the support.

What is your vision for the EGU ECS community and what do you hope to achieve as Union-level ECS representative in the time you hold the position?

I would like to see the ECS community more involved in organising sessions and shaping what the General Assembly looks like. We are running a short course on this year to accomplish these goals. I would also like to develop ways in which the ECS community could acknowledge established scientists that support ECS activities, but I would be interested in discussing just how to achieve this with the division ECS representatives.

How can those wanting to, get involved with the EGU?

There are lots of ways to get involved!

  1. See if your division is looking for an ECS representative and apply
  2. If the ECS representative position is taken, or if you’d rather not take on that role, ask if you can join the ECS team
  3. Fill in the surveys – this feedback is vital for us
  4. Attend the General Assembly ECS Forum (Thursday, 12 April at 12:15) and provide feedback
  5. Talk to your division ECS representative – either at one of the ECS events (ice-breaker, Networking & Careers Reception, Meet EGU) or you can shoot them an email


Interview by Olivia Trani, EGU Communications Officer


* The EGU communications officer is the ECS contact point at the EGU office.

MinCup: Elevating humble minerals to new heights

MinCup: Elevating humble minerals to new heights

Throughout October and November, the world of (Earth science) Twitter was taken by storm: Day after day, Eddie Dempsey (a lecturer at the University of Hull, and @Tectonictweets for those of you more familair with his Twitter handle) pitted minerals against each other, in a knock out style popular contest. The aim? To see which mineral would eventually be crowned the best of 2017.

Who knew fiery (but good natured) rows could explode among colleagues who felt, strongly, that magnetite is far superior to quartz or plagioclase? The Mineral Cup hashtag (#MinCup) was trending, it was in everyone’s mouth. Who would you vote for today?

What started as a little fun, became a true example of great science communication and how to bring a community of researchers, scattered across the globe, together.

And then Hazel Gibson (former EGU Press Assistant, @iamhazelgibson) came along. She was an active participant in the competition, but also contributed beautiful sketches of every mineral featured, and shared them for all to see by tagging them with the #MinCup hashtag. We all know that a picture is worth more than a thousand words, so when Hazel’s hand drawn sketches where paired with an already rocking contest, it’s impact and reach was truly cemented.

Between them, Eddie and Hazel had managed to elevate the humble mineral to new heights.

Why do minerals matter?

Minerals are hugely underrated. They are often upstaged by the heavy-weights of the geosciences: volcanoes, earthquakes, hurricanes, fossils and melting glaciers (to name but a few).

But they shouldn’t be.

Minerals are the building blocks of all rocks, which in turn, are the foundation of all geology.

Whether you study the processes which govern how rivers form, or ancient magnetic fields, or fossils, chances are your work will, at some stage, involve looking at, studying, or at the very least understanding (some) minerals. Mineralogy 101 (or whatever it’s precise name was at your university) is a rite of passage for any aspiring Earth scientist. I still remember hours spent painstakingly looking down a microscope, drawing and annotating sketches trying to decipher the secrets of the Earth’s ancient past, locked in minerals.

And that’s just the beginning.

Minerals are of huge economic and, therefore societal importance, too. Many minerals are vital ingredients in house-hold products and contribute to the manufacturing processes of many others. Yet, they fail to make headlines and their true significance, often, goes unnoticed.

So, in hopes to further highlight the relevance and importance of minerals, I’ve picked a few of the #MinCup minerals and explained why they (should) matter (to you).


Gypsum will form in lagoons, where ocean waters are high in calcium and sulfate content, and where the water evaporates slowly overtime. In rocks, it is associated with sedimentary beds which can be mined to extract the mineral, but it can also be produced by evaporating water with the right chemical composition.

Gypsum has been used in construction and decoration (in the form of alabaster) since 9000 B.C.  Today, it has a wide variety of common uses. Did you know that many fruit juice companies use gypsum to aid the extraction of the liquid? It is also used in bread and dough mixes as a raising agent. And it’s uses aren’t limited to just the food and drink industry. It is also commonly used as a modelling material for tooth restorations and helps keeps us safe when added to plastic products where it acts as a fire retardant.


Geologically speaking, magnetite holds the clues to understand the Earth’s ancient magnetic field. Credit: Hazel Gibson

Typically, greyish black or black, magnetite is an important iron ore mineral. It occurs in many igneous and volcanic rocks and is the most magnetic of all minerals. For it to form, magma has to cool, slowly, so that the minerals can form and settle out of the magma.

Due to its magnetic nature, it has fascinated human-kind for centuries: it paved the way for the invention of the modern compass.  The iron content in magnetite is higher than its more common cousin haematite, making it very sought after. Iron ore is the source of steel, which is used universally throughout modern infrastructure.

Geologically speaking, magnetite holds the clues to understand the Earth’s ancient magnetic field. As magnetite-bearing rocks form, the magnetite within them aligns with the Earth’s magnetic field. Since this rock magnetism does not change after the rock forms, it provides a record of what the Earth’s magnetic field was like at the time the rock formed.


Arguably, one of the most well-known of the minerals, diamond is unique, not only for its beauty and the high prices it reaches, but also for its properties. Not only is it the hardest known mineral, it is also a great conductor of heat and has the highest refractive index of any mineral.

Though mostly sought after by the jewellery industry, only 20% of all diamonds are suitable for use as a gem. Due to it’s hardness, diamond is mined for use in industrial processes, to be used as an abrasive and in diamond tipped saws and drills. Its optical properties mean it is used in electronics and optics; while it’s conductive properties mean it is often used as an insulator too.

Diamond: perhaps the most sought after mineral of them all? Credit: Hazel Gibson


Last, but absolutely not least, let’s talk about Olivine – the winner of #MinCup 2017.

Olivine is a pretty, commonly green mineral. Because it forms at very high temperatures, it is one of the first minerals to take shape as magma cools, and given enough time, can form specimens which are easily seen with the naked eye. Changes in the behaviour of seismic waves as they traverse the Earth indicate that Olivine is an important component of the Earth’s inner layer – the Mantle.

It’s a relatively hard mineral, but overall hasn’t got highly sought-after properties and, as result, has been used rather sparingly in industrial processes. In the past it has been used in blast furnaces to remove impurities from steel and to form a slag, as well as a refractory material, but both those uses are in decline as cheaper materials come to the market.

Perhaps better known is its gemstone counterpart: peridot, a magnesium rich form of Olivine. It has been coveted for centuries, with some arguing that Cleopatra’s famous ‘emeralds’, where in fact peridote. Until the mid-90s the US was the major exporter of the gem stones, but deposits in Pakistan and China now challenge the claim.

So, do you think Olivine was the rightful winner of #MinCup 2017? With a new edition of the popular contest set to return in 2018, perhaps it’s time to shout about the properties and uses of your favourite mineral from the roof tops? Not only might it ensure it is crowned winner next year, but you’ll also be contributing to making the value of minerals known to the wider public. Heck! If you’d like to tell us all about the mineral you think should be the next champion, why not submit a guest post to GeoLog?

In the meantime, if you haven’t already got your hands on one, Hazel tells me there are a few of her charity #MinCup 2017 calendars up for grabs, so make sure to secure your copy – and contribute to a good cause at the same time.

By Laura Roberts Artal, EGU Communications Officer

Imaggeo on Mondays: Smoking mountain top

Imaggeo on Mondays: Smoking mountain top

Japan’s northernmost, second largest and least developed island, Hokkaido, is famous for its unspoilt nature. Harsh, cold and snowy winters make way for pleasant summers, which allow tourists and locals to enjoy a variety of outdoor activities, year-round, in the island’s six protected areas.

The largest of the natural parks is Daisetsuzan: known for it’s wilderness and volcanoes. It is formed by the Daisetsuzan volcanic group, which is arranged around the Ohachidaira caldera. The highest peak of the group is Mt. Asahidake (2,291 m above sea level) and remains active. The Mt. Tokachi volcanic group, named after its highest peak Mt. Tokachi (also an active volcano), and the Ishikari Mountain Range, which includes the Mt. Shikaribetsu volcanic group near Lake Shikaribetsu and older geological strata of the Hidaka Mountain Range, make up the rest of the volcanic groups in the park.

Mt. Asahidake has not erupted since 1739, but constantly releases steam, which escapes from cracks across it’s volcanic slopes. According to Daniela Domeisen, who took the photograph we feature today:

“The fumaroles give the volcano its characteristic look and sulphuric smell.”

She goes on to describe the impressive volcanic setting:

“The mountain raises rather slowly, but with a steep and slippery peak. The descent on the opposite side is literally a secluded paradise, with the soil and the plants competing for the most beautiful patchwork of colour.”

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at