GeoLog

Field Work

Imaggeo on Mondays: One of the oldest evergreen rainforests in the world

Imaggeo on Mondays: One of the oldest evergreen rainforests in the world

A blazing sky and shimmers cast by water ripples frame the spectacular beauty of one of the world’s oldest treasures: an evergreen rainforest in Thailand. Today’s featured image was captured by Frederik Tack, of the Institute for Space Aeronomy in Brussels.

This picture was taken during sunset between the limestone mountains with the sunlight reflecting on beautiful Ratchaprapha lake in Khao Sok National Park.

Khao Sok National Park is one of the oldest evergreen rainforests in the world since Thailand has remained in a similar equatorial position throughout the last 160 million years. The climate in the area has been relatively unaffected by ice ages, as the landmass is relatively small and has seas on both sides. Even whilst other places on the planet were suffering droughts, the Khao Sok region still received enough rainfall to sustain the forest.

Khao Sok is also famous for its vertiginous limestone cliffs or ‘karst’ mountains. In most of the region, ground level is about 200m above sea level with the average mountain heights around 400m. The tallest peak in the National Park is 960m high. The national park area is inhabited by a large range of mammals such as tigers, elephants, tapirs and many monkey species. Birds such as hornbills, banded pittas and great argus are as well forest residents. Less commonly seen reptiles include the king cobra, reticulated python, and flying lizards.

One of the most interesting areas is stunningly beautiful Cheow Lan or Ratchaprapha Lake in the heart of the National Park. It is an 165-square-kilometre artificial lake, created in 1982, by the construction of Ratchaprapha Dam as a source of electricity.

By Frederik Tack, of the Institute for Space Aeronomy in Brussels

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/.

Malawi High School Teacher’s Workshop on Natural Hazards

Malawi High School Teacher’s Workshop on Natural Hazards

In July 2017, Professor Bruce Malamud and Dr Faith Taylor from King’s College London travelled to Mzuzu, Malawi to work in collaboration with Mr James Kushe from Mzuzu University, Malawi. They delivered an EGU funded workshop at Mzuzu University to high school teachers on natural hazards, with major funding provided by EGU, and also supported by Urban ARK and Mzuzu University. Faith and Bruce explain more about the trip…

Malawi is a small (118,000 km2) landlocked country in south eastern Africa, often referred to as the ‘warm heart of Africa’ due to its stability, safety, beauty and warm welcome to visitors. Yet behind this warm welcome, life for many in Malawi is hard; with an average GDP per capita of US$0.82 per day, high (although improving) prevalence of HIV-AIDs, tuberculosis and malaria and a range of natural disasters including earthquakes, floods, lightening, hail, strong winds and drought.

Although we are biased, we think life is particularly hard for Malawian Geography teachers who have a great responsibility to shape the next generation of big-thinkers and problem-solvers against the challenges such as (i) large class sizes, (ii) limited opportunity for teachers’ continued professional development and (iii) under-resourcing of schools.

With this in mind, Bruce, James and I applied for EGU funding to run a workshop for teachers on natural hazards, focusing particularly on: (i) collating and developing low-cost teaching demonstrations, (ii) equipping teachers with further information about natural hazards and (iii) learning more about their home city of Mzuzu as a resource for field trips.

Professor Bruce Malamud demonstrating seismic waves using a giant slinky.

In the months running up to the workshop, we prepared 16 Gb USB sticks for each teacher which included >35 teaching demos that we had created and/or reviewed, and then trialled, 77 videos that we selected from the many out there, 11 digital posters and 16 factsheets and 14 Powerpoint lectures from our own teaching. We also started to order a few resources that would be hard to come by in Malawi, such as slinkies for teaching about earthquake waves and mento tubes for demonstrating volcanic eruptions (try explaining a suitcase of slinkies to a customs official!).

In Mzuzu, James visited each highschool to explain the purposes of our workshop and get local interest, planned a fieldtrip to the Massassa region and started to purchase locally available resources for teaching demonstrations, such as jars and sand for teaching about the angle of repose with regard to landslides.

Upon arrival at the Mzuzu University library, where we held the workshop, we were greeted by 27 high school teachers who had travelled from up to a couple of hours away to spend three days with us. The schools they came from varied in terms of resourcing, teachers’ background and experience, but all teachers were enthusiastic about the opportunity to learn more (note to others, teachers were particularly keen on further EGU funded workshops on other topics!).

Over the three days, we delivered interactive undergraduate level lectures on a range of natural hazards, so that teachers would better understand the process behind many of the hazards, interspersed with over two dozen activities and teaching demonstrations that they could bring back to the classroom. We also had a half day microadventure facilitated by one of the teachers to a local area that had been affected by flooding and landslides. This was a good reminder that geography starts on the doorstep, and does not require expensive fieldtrips to exotic destinations to help students experience environmental phenomena and solidify their classroom based learning. There were also opportunities for the teachers to share some of their best practice – and from this, we hope the seed has been sown for teachers to establish their own professional network for sharing ideas and resources.

We have travelled to Malawi multiple times over the past few years as part of our work on the Urban ARK project where we look at multi-hazard risk to infrastructure. From this work, we know how challenging it can be for information and ideas to flow to those experiencing and managing risks. We left Malawi feeling hopeful that through those 27 bright and enthusiastic teachers, we might reach >2000 students, and through those students we might also reach their friends and family to help reduce disaster risk across the Mzuzu region.

In the coming months we will share some of the resources we generated and collated online. There is a clear need for further workshops like this across Malawi, and an appetite for building a network of teachers. It took a lot of planning and partnerships with local academics but we would strongly encourage others to consider running similar workshops for teachers in the warm heart of Africa.

By Faith Taylor and Bruce Malamud, King’s College London

GeoTalk: The anomaly in the Earth’s magnetic field which has geophysicists abuzz

GeoTalk: The anomaly in the Earth’s magnetic field which has geophysicists abuzz

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Jay Shah, a PhD student at Imperial College London, who is investigating the South Atlantic Anomaly, a patch over the South Atlantic where the Earth’s magnetic field is weaker than elsewhere on the globe. He presented some of his recent findings at the 2017 General Assembly.

First, could you introduce yourself and tell us a little more about your career path so far?

I’m currently coming to the end of my PhD at Imperial College London. For my PhD, I’ve been working with the Natural Magnetism Group at Imperial and the Meteorites group at the Natural History Museum, London to study the origin of magnetism in meteorites, and how meteoritic magnetism can help us understand early Solar System conditions and formation processes.

Before my PhD I studied geology and geophysics, also at Imperial, which is when I studied the rocks that I spoke about at the 2017 EGU General Assembly.

What attracted you to the Earth’s magnetic field?

Jay operates the Vibrating Sample Magnetometer at the lab at Imperial. Credit: Christopher Dean/Jay Shah

My initial interest in magnetism, the ‘initial spark’ if you like, was during my undergraduate, when the topic was introduced in standard courses during my degree.

The field seemed quite magical: palaeomagnetists [scientists who study the Earth’s magnetic field history] are often known as palaeomagicians. But it’s through rigorous application of physics to geology that palaeomagicians can look back at the history of the Earth’s magnetic field recorded by rocks around the world. I was attracted to the important role palaeomagnetism has played in major geological discoveries such as plate tectonics and sea-floor spreading.

Then, during my undergraduate I had the opportunity to do some research alongside my degree, via the ‘Undergraduate Research Opportunities Programme’ at Imperial. It was certainly one of the bonuses of studying at a world-class research university where professors are always looking for keen students to help move projects forward.

I was involved in a project which focused on glacial tillites [a type of rock formed from glacial deposits] from Greenland to look into inclination shallowing; which is a feature of the way magnetism is recorded in rocks that can lead to inaccurate calculation of palaeolatitutdes [the past latitude of a place some time in the past]. Accurate interpretation of the direction of the Earth’s magnetic field recorded by rocks is essential to reconstructing the positions of continents throughout time.

This was my first taste of palaeomagnetism and opened the doors to the world of research.

So, then you moved onto a MSci where one of your study areas is Tristan da Cunha, a volcanic island in the South Atlantic. The location of the island means that you’ve dedicated some time to studying the South Atlantic Anomaly (SAA). So, what is it and why is it important?

The SAA is a present day feature of the magnetic field and has existed for the past 400 years, at least, based on observations. It is a region in the South Atlantic Ocean where the magnetic field is weaker than it is expected to be at that latitude.

The Earth’s magnetic field protects the planet and satellites orbiting around Earth from charged particles floating around in space, like the ones that cause aurorae. The field in the SAA is so weak that space agencies have to put special measures in place when their spacecraft orbit over the region to account for the increased exposure to radiation. The Hubble telescope, for example, doesn’t take any measurements when it passes through the SAA and the International Space Station has extra shielding added to protect the equipment and astronauts.

If you picture the Earth’s magnetic field:  it radiates from the poles towards the Earth’s equator, like butterfly wings extending out of the planet. In that model, which is what palaeomagnetic theory is based on, it is totally unexpected to have a large area of weakness.

Earth’s magnetic field connects the North Pole (orange lines) with the South Pole (blue lines) in this NASA-created image, a still capture from a 4-minute excerpt of “Dynamic Earth: Exploring Earth’s Climate Engine,” a fulldome, high-resolution movie. Credit: NASA Goddard Space Flight Center

We also know that the Earth’s magnetic field reverses (flips its polarity), on average, every 450,000 years. However, it has been almost twice as long since we have had a flip, which means we are ‘overdue’ a reversal. People like to look for signs that the field will reverse soon; could it be that the SAA is a feature of an impending (in geological time!) reversal? So, it becomes important to understand the SAA in that respect too.

So, how do you approach this problem? If the SAA is something you can’t see, simply measure, how do you go about studying it?

Palaeomagnetists can look to the rock record to understand the history of the Earth magnetic field.

Volcanic rocks best capture Earth’s magnetic field because they contain high percentages of iron bearing minerals, which align themselves with the Earth’s magnetic field as the lavas cool down after being erupted. They provide a record of the direction and the strength of the magnetic field at the time they were erupted.

In particular, I’ve been studying lavas from Tristan da Cunha (a hotspot island) in the Atlantic Ocean similar in latitude to South Africa and Brazil. There are about 300 people living on the island, which is still volcanically active. The last eruption on the island was in 1961. In 2004 there was a sub-marine eruption 24 km offshore.

Jürgen Matzka (GFZ Potsdam) collected hundreds and hundreds of rock cores from Tristan da Cunha on sampling campaigns back in 2004 and 2006.

We recently established the age of the lavas we sampled as having erupted some 46 to 90 thousand years ago. Now that we know the rock ages, we can look at the Earth’s magnetic field during this time window.

Why is this time window important?

These lavas erupted are within the region of the present day SAA, so we can look to see whether any similar anomalies to the Earth’s magnetic field existed in this time window.

So, what did you do next?

Initial analyses of these rocks focused on the direction of the magnetic field recorded by the rocks. The directional data can be used to trace back past locations of the Earth’s magnetic poles.

Then, during my master’s research dissertation I had the opportunity to experiment on the rocks from Tristan da Cunha with the focus on palaeointensity [the ancient intensity of the Earth’s magnetic field recorded by the rocks]. We found that they have the same weak signature we observe today in the SAA but in this really old time window.

The rocks from Tristan da Cunha, 46 to 90 thousand years ago, recorded a weaker magnetic field strength compared to the strength of the magnetic field of the time recorded by other rocks around the world.

Some of the lavas sampled on Tristan da Cunha. Credit: Jürgen Matzka

What does this discovery tell us about the SAA?

I mentioned at the start of the interview that, as far as we thought, the anomaly didn’t extend back more than 400 years ago – it’s supposed to be a recent feature of the field. Our findings suggest that the anomaly is a persistent feature of the magnetic field. Which is important, because researchers who simulate how the Earth’s magnetic field behaved in the past don’t see the SAA in simulations of the older magnetic field.

It may be that the simulations are poorly constrained. There are far fewer studies (and samples) of the Earth’s magnetic directions and strengths from the Southern Hemisphere. This inevitably leads to a sampling bias, meaning that the computer models don’t have enough data to ‘see’ the feature in the past.

However, we are pretty certain that the SAA isn’t as young as the simulations indicate. You can also extract information about the ancient magnetic field from archaeological samples. As clay pots are fired they too have the ability to record the strength and direction of the magnetic field at the time. Data recorded in archaeological samples from southern Africa, dating back to 1250 to 1600 AD also suggest the SAA existed at the time.

Does the fact that the SAA is older than was thought mean it can’t used be to indicate a reversal?

It could still be related to a future reversal – our findings certainly don’t rule that out.

However, they may be more likely to shed some light on how reversals occur, rather than when they will occur.

It’s been suggested that the weak magnetic anomaly may be a result of the Earth’s composition and structure at the boundary between the Earth’s core and the mantle (approximately 3000 km deep, sandwiched between the core and the Earth’s outermost layer known as the crust). Below southern Africa there is something called a large low shear velocity province (LLSVP), which causes the magnetic flux to effectively ‘flow backwards’.

These reversed flux patches are the likely cause of the weak magnetic field strength observed at the surface, and could well indicate an initiating reversal. However, the strength of the Earth’s magnetic field on average at present is stronger than what we’ve seen in the past prior to field reversals.

The important thing is the lack of data in the southern hemisphere. Sampling bias is pervasive throughout science, and it’s been seen here to limit our understanding of past field behaviour. We need more data from around the world to be able to understand past field behaviour and to constrain models as well as possible.

Sampling bias is pervasive throughout science, and it’s been seen here to limit our understanding of past field behaviour. This image highlights the problem (black dots = a sampling location). Modified from an image in the supporting materials of Shah, J., et al. 2016. Credit: Jay Shah.

You are coming towards the end of your PhD – what’s next?

So I moved far away from Tristan da Cunha for my PhD and have been looking at the magnetism recorded by meteorites originating from the early Solar System. I’d certainly like to pursue further research opportunities working with skills I’ve gained during my PhD. I want to continue working in the magical world of magnetism, that’s for sure! But who knows?

Something you said at the start of the interview struck me and is a light-hearted way to round-off our chat. You said that palaeomagnetism are often referred to as ‘paleaomagicians’ by others in the Earth sciences, why is that so?

Over the history of the geosciences, palaeomagntists have contributed to shedding light on big discoveries using data that not very many people work with. It’s not a big field within the geosciences, so it’s shrouded in a bit of mystery. Plus, it’s a bit of a departure from traditional geology, as it draws so heavily from physics. And finally, it’s not as well established as some of the other subdisciplines within geology and geophysics, it’s a pretty young science.  At least, that’s why I think so, anyway!

Interview by Laura Roberts Artal, EGU Communications Officer

References and further reading

Shah, J., Koppers, A.A., Leitner, M., Leonhardt, R., Muxworthy, A.R., Heunemann, C., Bachtadse, V., Ashley, J.A. and Matzka, J.: Palaeomagnetic evidence for the persistence or recurrence of geomagnetic main field anomalies in the South AtlanticEarth and Planetary Science Letters441, pp.113-124, doi: 10.1016/j.epsl.2016.02.039, 2016.

Shah, J., Koppers, A.A., Leitner, M., Leonhardt, R., Muxworthy, A.R., Heunemann, C., Bachtadse, V., Ashley, J.A. and Matzka, J.: Paleomagnetic evidence for the persistence or recurrence of the South Atlantic geomagnetic Anomaly. Geophysical Research Abstracts, Vol. 19, EGU2017-7555-3, 2017, EGU General Assembly 2017.

Imaggeo on Mondays: What happens to mines when they become redundant?

Imaggeo on Mondays: What happens to mines when they become redundant?

When the minerals run out, or it is no longer profitable to extract the resources, mines shut down. Prior to issuing a permit for the exploitation of a resource, most regulators require assurance that once the mine closes it, or the activities carried out at the site, will not present a risk to human health or the environment.

Ongoing monitoring of a mine once it is decommissioned is required to ensure this is the case.

“The goal of my work is to study the environmental impact of mining waste in the north-east part of Algeria,” explains Issaad Mouloud, author of today’s featured image.

Algeria has a long history of mining. Since the antiquity and the time of the Berbers, many minerals and ores deposits were exploited. The northeast was the most productive region in the country. The geology of the study area is composed of magmatic and metamorphic rocks, sandstone and limestone.

Kef Oum Theboul mining district is located on the Eastern cost of Algeria, 4 km west of the Tunisian border. It is located 15 km from the town of El Kala. The Kef Oum Theboul site covers an area of 26.6 km2 and which contains copper lead and zinc ore

Discovered in 1845, the Kef Oum Teboul ore deposits were mined from 1849 to the 1970s. The Messida ore plant, pictured above and located not far from the Kef Oum Teboul deposit, is one of Issaad’s study sites.

The ore plant, situated in the Algerian Mediterranean coast, on Messida beach (located 6km from Kef Oum Teboul) processed copper, lead and zinc mineralizations.  Processing at the plant started in 1899.  It had three water jacket furnaces, with a capacity of 50 tons of ore per 24 hours. The obtained matte contained 20-22% copper, 200 grams of silver and 11-12 grams of gold per ton.

“The plant is now totally destroyed but mining waste, mainly sulphur ore and slag, is still stored in the Messida area,” explains Issaad, who goes on to say “the main pollution factor which I study is the acid mine drainage and heavy metals.”

 

Abandoned sulphurous ore and slag stored in the ruins of the ore processing plant of Messida. Credit: Issaad Mouloud

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/.