GeoLog

Earth Magnetism and Rock Physics

Imaggeo on Mondays: River in a charoite schist

Imaggeo on Mondays: River in a charoite schist

Polarized light photomicrograph of a thin section of a charoite-bearing schist.

Charoite is a rare silicate found only at one location in Yakutia, Russia. For its beautiful and uncommon purple color it is used as a semi-precious stone in jewelry.

Under the microscope charoite-bearing rocks give an overall feeling of movement, with charoite forming fibrous mats that swirl and fold as a result of deformation during metamorphism.

Due to the variable orientation with respect to the polarized light the charoite may exhibit different interference colors. It may be difficult to conceive, but these microstructures tell us that solid rocks can flow! Width of view: 5,4 mm.

Description by Bernardo Cesare, as it first appeared on imaggeo.egu.eu

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 http://imaggeo.egu.eu/upload/.

 

April GeoRoundUp: the best of the Earth sciences from the 2018 General Assembly

April GeoRoundUp: the best of the Earth sciences from the 2018 General Assembly

The 2018 General Assembly took place in Vienna last month, drawing more than 15,000 participants from 106 countries. This month’s GeoRoundUp will focus on some of the unique and interesting stories that came out of research presented at the Assembly.

Mystery solved

The World War II battleship Tirpitz was the largest vessel in the German navy, stationed primarily off the Norwegian coastline as a foreboding threat to Allied armies. The ship was 250 metres in length and capable of carrying around 2,500 crewmates.

Despite its massive size, the vessel’s presence often went unnoticed as it moved between fjords, masked by a chemical fog of chlorosulphuric acid released by the Nazi army.

Ultimately the ship sank and the war ended, but evidence of the toxic smog still lingers today, in the tree rings of Norway’s nearby forests.

Claudia Hartl, a dendrochronologist from the Johannes Gutenberg University in Mainz, Germany, made this discovery unexpectedly while sampling pines and birches near the Norwegian village Kåfjord. She and her research team presented their findings at the General Assembly in Vienna last month.

The German battleship Tirpitz partly covered by a smokescreen at Kaafjord. (Image Credit: Imperial War Museums )

Hartl had been examining wood cores to draw a more complete picture of past climate in the region when she noticed that some trees completely lacked rings dating to 1945,” reported Julissa Treviño in Smithsonian Magazine.

The discovery was odd since it is rare for trees to have completely absent rings in their trunks. Tree ring growth can be stunted by extreme cold or insect infestation, but neither case is severe enough to explain the missing tree rings from that time period.

“A colleague suggested it could have something to do with the Tirpitz, which was anchored the previous year at Kåfjord where it was attacked by Allied bombers,” explains Jonathan Amos from BBC News.

The researchers indeed found physical and chemical evidence of the smokescreen damage on the trees, demonstrating the long-lasting impact warfare can impart onto the environment.

 

What you might have missed

Seismicity of city life

Researchers use seismometers to record Earth’s quakes and tremors, but some seismologists have employed these instruments for a different purpose, to show how humans make cities shake. “This new field of urban seismology aims to detect the vibrations caused by road traffic, subway trains, and even cultural activities,” reports EGU General Assembly Press Assistant Tim Middleton on GeoLog.

With seismometers, Jordi Díaz and colleagues at the Institute of Earth Sciences Jaume Almera in Barcelona, Spain have been able to pick up the seismic signals of major football games and rock concerts, like footballer Lionel Messi’s winning goal against Paris Saint-Germain and Bruce Springsteen’s Barcelona show.

Seismic record captured by the seismometer during the Bruce Springsteen concert. The upper panel shows the seismogram, while the lower panel shows the spectrogram where it is possible to see the distribution of the energy between the different frequencies. (Image Credit: Jordi Díaz)

Díaz’s project first began as an outreach campaign, to teach the general public about seismometers, but now he and his colleagues are exploring other applications. For example, the data could help civil engineers with tracking traffic and monitoring how buildings withstand human-induced tremors.

Antarctica seeing more snow

Meanwhile in Antarctica, snowfall has increased by 10 percent in the last 200 years, according to new research presented at the meeting. After analysing 79 ice cores, a research team led by Liz Thomas from the British Antarctic Survey discovered that Antarctica’s increased snowfall since 1800 was equivalent to 544 trillion pounds of water, about twice the volume of the Dead Sea.

It has been predicted that snowfall increase would be a consequence of global warming, since a warmer atmosphere can hold more moisture, thus resulting in more precipitation. However, these ice core observations reveal this effect has already been happening. The new finding implies that Earth’s sea level has risen slightly less than it would have otherwise, but only by about a fifth of a milimetre. Though overall, this snowfall increase is not nearly enough to offset Earth’s increased ice loss.

Ocean’s tides create a magnetic field

Also at the Assembly, scientists presented new data collected from a team of ESA satellites known as Swarm, In particular, the satellite observations recently mapped magnetic signals induced by Earth’s ocean tides. As the planet’s tides ebb and flow, drawn by the Moon’s gravitational pull, the salty water generates electric currents. And these currents create a tiny magnetic field, around 20,000 times weaker than the global magnetic field.

Scientists involved with the Swarm project say the magnetic view provides new insight into Earth’s ocean flow and magnetic field, can improve our understanding of climate change, and help researchers build better Earth system models.

When salty ocean water flows through Earth’s magnetic field, an electric current is generated, and this in turn induces a magnetic signal. (Credit: ESA/Planetary Visions)

 

Other noteworthy stories:

 

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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 

References

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, https://doi.org/10.1002/2014TC003622, 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), https://doi.org/10.1002/2015JB012382, 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, https://doi.org/10.1016/j.jsames.2017.04.014, 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 http://imaggeo.egu.eu/upload/.

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.