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Imaggeo on Mondays: Exploring the East African Rift

10 Mar

This week’s Imaggeo on Mondays is brought to you by Alexis Merlaud, an atmospheric scientist from the Belgian Institute for Space Aeronomy. While the wonders of the African atmosphere feature in his photography, the East African Rift has a much bigger tale to tell. Drawing from all aspects of geoscience Alexis shares its story…

Kilimanjaro from Mount Meru. (Credit: Alexis Merlaud, distributed via imaggeo.egu.eu)

Kilimanjaro from Mount Meru. (Credit: Alexis Merlaud, distributed via imaggeo.egu.eu)

This picture shows Kilimanjaro, Africa’s highest mountain, at sunrise. It was taken from Socialist Peak, which marks the top of Mount Meru, some 70 km to the southwest. Both mountains are located in Tanzania and are among the largest stratovolcanoes of the East African Rift Zone. Unlike Kilimanjaro, Meru is active and its most recent eruption occurred in 1910.

Stratovolcanoes, also called composite cones, are built-up by alternating layers of lava flows, pyroclastic rocks, and volcanic ash. During a large eruption, huge quantities of ash and sulphur dioxide can reach the stratosphere, where they can affect the climate for several years, as did the eruptions of Krakatau in 1883 and Pinatubo in 1991. Sulphur dioxide is converted to sulphuric acid droplets, which spread with the ashes throughout the stratosphere. These aerosols screen some of the sunlight, decreasing the average surface temperature by about one degree. The temperature in the stratosphere simultaneously rises by a few degrees, due to the enhanced absorption of sunlight by aerosols.

There is a difference in the tectonic processes associated with these South East Asian volcanoes and the East African Rift: the former are located above a subduction zone while the rift is a divergent boundary.  An example of large volcanic eruption in a divergent zone is the Laki (Iceland) eruption in 1783, which yielded severe meteorological conditions and reduced harvests for several years in Europe. This eruption may have also helped trigger the French Revolution in 1789.

Plate tectonics in East Africa created Kilimajaro and have also played a role in early human evolution, by shaping the local landscape and the long-term climate, thus modifying the environment of our ancestors. East Africa is the area in the world where most of the hominid fossils have been discovered, including Homo sapiens – the oldest fossil record is 200,000 years old and started to move out from Africa 100,000 years ago!

A final thanks: thanks Cristina Brailescu for help climbing Meru and Emmanuel Dekemper for support on editing the picture. 

By Alexis Merlaud, Belgian Institute for Space Aeronomy

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Imaggeo on Mondays: Iceland’s highlands

3 Mar

This week’s Imaggeo on Mondays provides a little insight into what you might find beneath your feet as you explore the Icelandic highlands… 

Autumn mountain vegetation, Central Highland, Iceland. (Credit: Ragnar Sigurdsson/arctic-images.com via imaggeo.egu.eu)

Autumn mountain vegetation, Central Highland, Iceland. (Credit: Ragnar Sigurdsson/arctic-images.com, distributed via imaggeo.egu.eu)

You can stumble upon wild blueberries, better known to botanists as vaccinium uliginosum, in cool temperate regions of the Arctic, as well as other mountainous areas including the Pyrenees, Alps, and Rockies. They thrive in wet acidic soils – the sort you might find in heathlands, moorlands and stretches of Arctic tundra, and can carpet the ground beneath coniferous forests too!

Here’s a close-up! (Credit: Kim Hansen via Wikimedia Commons)

Here’s a close-up! (Credit: Kim Hansen via Wikimedia Commons)

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Last chance to enter the EGU Photo Contest!

26 Feb

If you are pre-registered for the 2014 General Assembly (Vienna, 27 April – 2 May), you can take part in our annual photo competition! Winners receive a free registration to next year’s General Assembly!

Every year we hold a photo competition and exhibit in association with our open access image repository, Imaggeo and our annual General Assembly. Last year, we also introduced a moving image competition, which features a short clip of continuous geoscience footage. Pre-registered conference participants can take part by submitting up to three original photos and/or one moving image on any broad theme related to the Earth, planetary and space sciences.

How to enter

You will need to register on Imaggeo to upload your image, which will also be included in the database. When you’ve uploaded it, you’ll have the option to edit the image details – here you can enter it into the EGU Photo Contest – just check the checkbox! The deadline for submissions is 1 March.

previous winners

Past Photo Contest winners (clockwise from left): “Frost” by Philipp Stadler, “Melt Stream, Greenalnd” by Ian Joughin, “Geysir” by James Levine and “Patterns in the Void” by Christian Klepp.

For more information, check the EGU Photo Contest page. We look forward to receiving your entries!

Imaggeo on Mondays: Friends in the field

24 Feb

Out in the field you encounter all sorts of wildlife and while mosquitos are the most frequent (and most unwelcome), they generally don’t interfere with your equipment or your data. The same can’t be said for all animals though, and many scientists have to strap their equipment out of reach, barricade it with barbed fences or place it in a relatively indestructible black box. It’s a particular problem when you need to head back to the lab or lecture theatre, and leave your equipment alone to collect precious scientific data remotely.

Animals can also cause a ruckus when you’re on site – after all, what’s more exciting than a geoscientist and their portable laboratory? This is surely the question that played on the minds of these bovine beasties before interfering with a geoelectrical survey, a method used to monitor CO2 storage and map groundwater.

Does it work? (Credit: Robert Supper, distributed via imaggeo.egu.eu)

Does it work? (Credit: Robert Supper, distributed via imaggeo.egu.eu)

While surveying groundwater in Salzburg, Austria, Robert Supper caught a crowd of curious cows taking a closer look at his equipment. “During the measurements on a meadow, we were inspected by a drove of cows, which immediately started to taste electrodes and cables,” he explains.

“On geoelectrical surveys in rural areas, we often encounter an interesting phenomenon: cows or sheep completely ignore us until we finish the installation of cables and electrodes. As soon as we are ready and want to start the measurements, they start to inspect everything, sniff on the equipment, nibble on the cables, stumble over the profile or (worst case) shit on it. If everything was tested correctly by them, they disappear,” Supper adds. Take care when you’re working in a rural area, you might just get some company.

By Sara Mynott, EGU Communications Officer

If you are pre-registered for the 2014 General Assembly (Vienna, 27 April – 2 May), you can take part in our annual photo competition! Up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

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