Geochemistry, Mineralogy, Petrology & Volcanology

Imaggeo on Mondays: night cap over Mt. Fuji

Imaggeo on Mondays: night cap over Mt. Fuji

The first Imaggeo on Monday’s post of 2016 is quite spectacular! It features a lenticular cloud capping the heights of Mount Fuji, in Japan. Erricos Pavlis writes this post and describes how the unusual cloud formation comes about and why Mt. Fuji is such a prime place to catch a glimpse of this meteorological phenomena.

Mount Fuji at more than 3700 m is one of the highest volcanoes in the world and the highest mountain in Japan,located some one hundred or so kilometers southwest of Tokyo.

In November 2013 the International Laser Ranging Service (ILRS) held its annual Int. Laser Ranging Workshop at Fujiyoshida, a resort town very close to the volcano. The venue had a clear shot at the volcano and rewarded us daily with spectacular views of the entire volcano. On the first morning of my stay, November 9, I looked out the window very early on and Mt. Fuji was toped with a lenticular cloud, just like a nightcap for a cold winter night.

Being such a tall mountain and the only one in the area, Mt. Fuji is a perfect candidate to observe this rare kind of clouds that form in the troposphere and mostly over very tall topographic features. The lenticular clouds (formally called Altocumulus lenticularis) are the result of the obstructed wind flow due to an barrier, a mountain for example, but it could also happen with man-made obstacles like very tall buildings. They are formed at right angles to the wind direction and they are categorized in several different types, however, they all have the shape of lens and this has sometimes led viewers believe they saw an Unidentified Flying Object (UFO)! On rare occasions, the lucky ones might see several of these stacked on top of each other with thin layers of air separating them like a pile of pancakes! Even the single one was for me a very pleasant surprise though!

By Erricos Pavlis, Joint Center for Earth Systems Technology, Univ. of Maryland, Baltimore County, Baltimore, Maryland, United States of America.

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

Geoscience hot topics – The finale: Understanding planet Earth

Geoscience hot topics – The finale: Understanding planet Earth

What are the most interesting, cutting-edge and compelling research topics within the scientific areas represented in the EGU divisions? Ground-breaking and innovative research features yearly at our annual General Assembly, but what are the overarching ideas and big research questions that still remain unanswered? We spoke to some of our division presidents and canvased their thoughts on what the current Earth, ocean and planetary hot topics will be.

Because there are too many to fit in a single post we’ve brought some of them together in a series of posts which will tackle three main areas. The first post focused on the Earth’s past and its origin, while the second post focused on the Earth as it is now and what its future looks like. Today’s is the final post of the series and will explore where our understanding of the Earth and its structure is still lacking. We’d love to know what the opinions of the readers of GeoLog are on this topic too, so we welcome and encourage lively discussion in the comment section!

A new, modern, era for research

That we have great understanding of the Earth, its structure and the processes which govern how the environment works, is a given. At the same time, so much is still unknown, unclear and uncertain, that there are plenty of research avenues which can help build upon, and further, our current understanding of the Earth system.

By Camelia.boban (Own work) [CC BY-SA 3.0], via Wikimedia Commons

Big Data’s definition illustrated with text. Credit: Camelia.boban (Own work) [CC BY-SA 3.0], via Wikimedia Commons

As research advances, so do the technologies which allow scientist to collect, store and use data. Crucially, the amount of data which can be collected increases too, opening avenues not only for scientists to carry out research, but for the wider population to be involved in scientific research too: the age of Big Data and Citizen Science is born.

The structure of the Earth

Despite a long history of study, including geological maps, studies of the structure of the Alps, and the advent of analogue models some 200 years ago, there is much left to learn about how geological processes interact and shape our Earth.

Some important unanswered questions in the realm of Tectonics and Structural Geology (TS) include:

“Why do some passive margins have high surface topography (take Norway, or Southeastern Brazil as an example) even millions of years after continental break-up? How does subduction, the process by which a tectonic plate slides under another, begin? And how does the community adapt to new research methods and ever growing datasets?” highlights Susanne Buiter, TS Division.

One important problem is that of inheritance and what role it plays in how plate tectonics work. Scientists have known, since the theory was first proposed in the 1950s (although it only became broadly accepted in the 1970s), that our planet is active: its outer shell is divided into tectonic plates which slide, collide, pull away and sink past one another. During their life-time the tectonic plates interact with surface process and eventually flow into the mantle below. This implies that any new tectonic processes will take place in material that carries a history.

“It is increasingly recognised that tectonic events do not act on homogenous, pristine materials, but more likely on crust that is cross-cut by old shear zones, incorporates different lithologies and which may have inherited heat from previous deformation events (such as folding),” explains Susanne.

So the key is: what is the impact of historical inheritance on tectonic events? Can old structures be reactivated and if so, when are they reactivated and when not? Do the tectonic processes control the resulting structures or is it the other way around?

Seismology too can shed more light on how we understand Earth processes and the structure of the planet.

“An emerging field of research is seismic super-resolution: a promising technique which allows imaging of the fine-scale subsurface Earth structure in more detail than has been possible ever before,” explains Paul Martin Mai, President of the Seismology (SM) Division.

The methodology has applications not only for our understanding of the structure and process which take place on Earth, but also for the characterisation of fuel reservoirs and identification of potential underground storage facilities. That being said, the technique is still in its infancy and more research, particularly applied to ‘real’ geological settings is needed.

Understanding natural hazards

The reasons to pursue further understanding in this area are diverse and wide-ranging: amongst the most relevant to society is being able to better comprehend and predict the processes which lead to natural disasters.

Earthquake 1920 (?). Credit: Konstantinos Kourtidis (distributed via

Earthquake 1920 (?). Credit: Konstantinos Kourtidis (distributed via

It goes without saying that, due to their destructive nature, earthquakes are a topic of continued cross-disciplinary scientific research. Generating more detailed images of the Earth’s structure, using seismic super-resolution for instance, can also improve our understanding of how and why earthquakes occur, as well as helping to determine large-scale fault behaviour.

And what if we could crowd source data to help us understand earthquakes better too? LastQuake is an online tool, operated via Twitter and an app for smartphones which allows users to record real-time data regarding earthquakes. The results are uploaded to the European-Mediterranean Seismological Centre (EMSC) website where they offer up-to-data information about ongoing shake events. It was used by over 8000 people during the April 2015 Nepal earthquakes to collect eyewitness observation, including geo-located pictures, testimonies and comments, in the immediate aftermath of the earthquake.

In this setting, citizens become scientists too. They contribute data, by acquiring it themselves, which can be used to answer research questions. In the case of LastQuake, the use of the data is immediate and can contribute towards easing rescue operations and alerting citizens of dangerous areas (for instance where buildings are at risk of collapse) providing a two-way communication tool.

Global temperatures and climate change

It is not only earthquakes that threaten communities. Just as destructive can be extreme weather events, such as typhoons, cyclones, hurricanes, storm surges, severe rainfalls leading to flooding or droughts. With the increased frequency and destructiveness of these events being linked to climate change understanding global temperature fluctuations becomes more important than ever.

Flooded Mekong. Credit: Anna Lourantou (distributed via

Flooded Mekong. Credit: Anna Lourantou (distributed via

Over periods of months, years and decades global temperatures fluctuate.

“Up to decades, the natural tendency to return to a basic state is an expression of the atmosphere’s memory that is so strong that we are still feeling the effects of century-old fluctuations,” says Shaun Lovejoy, President of the Nonlinear Processes Division (NP).

Harnessing the record of past-temperature fluctuations, as recorded by the atmosphere, can provide a more accurate way to produce seasonal forecasts and long-term climate predictions than traditional climate models and should be explored further.

Geoscience hot topics

Be it studying the Earth’s history, how to sustainably develop our communities, or simply understanding the basic principles which govern how our planet – and others – operates, the scope for avenues of research in the geosciences is vast. Moreover, the advent of new technologies, data acquisition and processing techniques allow geoscientists to explore more complex problems in greater detail than was ever possible before. It’s an exciting time for geoscientific research.

By Laura Roberts Artal in collaboration with EGU Division Presidents

Imaggeo on Mondays: Giants Causeway

Imaggeo on Mondays: Giants Causeway

Since its discovery back in the late 1600s the origin of the spectacular polygonal columns of the Giants Causeway, located on a headland along the northern coast of Ireland, has been heavily debated. Early theories for its origin ranged from being sculpted by men with picks and chisels, to the action of giants, through to the force of nature. It wasn’t until 1771 that Demarest, a Frenchman, suggested that the origin of the world-famous headland was indeed volcanic.

“The myth goes that the Irish giant Finn MacCool once constructed a land bridge from Northern Ireland to Scotland in order to meet a rival giant,“ explains Bernhard Aichner, author of this week’s featured imaggeo image. “It is said that he used basaltic rocks from the surrounding cliffs to construct the bridge. Finn´s rival later destroyed most of the causeway, but the remnants still can be seen today as basalt columns descending into the sea.“

We now know that the hexagonal columns along the rugged Irish coastline formed some sixty million years ago, during a time when the ancestors to modern plant species started to emerge and the Earth was going through a period of warming. At the time, Antrim (a modern-day county of Ireland), was subjected to an intense period of volcanic activity as a result of the opening of the Atlantic Ocean.

The Giants Causeway is only a small part of a vast network of lava flows which extended over the Antrim landscape; much of which, through the passage of time, has been eroded away. There were three distinct periods of volcanic activity which resulted in a thick succession of lava flows which has been subdivided into the Lower, Middle and Upper Basalts.

The lavas of the Giants Causeway belong to the Middle Basalts and comprise over 40,000 vertical columns. Recently, a new model was proposed for the formation of the striking polygonal pattern formed by the columns. They formed within a lava flow, which contracted and fractured while cooling very slowly. If the loss of heat is steady, then the pattern formed is uniform, but if areas cool faster than others, the fractures develop unevenly, meaning the columns form in a variety of sizes and shapes: expect anything from pentagons to heptagons if you get a chance to visit the Causeway!

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


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