GeoLog

Tectonics and Structural Geology

Imaggeo on Mondays: The largest fresh water lake in world

Lake shore in Siberia. Credit: Jean-Daniel Paris (distributed via imaggeo.egu.eu)

Lake shore in Siberia. Credit: Jean-Daniel Paris (distributed via imaggeo.egu.eu)

Most lakes in the Northern hemisphere are formed through the erosive power of glaciers during the last Ice Age; but not all. Lake Baikal is pretty unique. For starters, it is the deepest fresh water lake in the world. This means it is the largest by volume too, holding a whopping 23,615.39 cubic kilometres of water. Its surface area isn’t quite so impressive, as it ranks as the 7th largest in the world. However, it makes up for that by also being the world’s oldest lake, with its formation dating back 25 million years – a time during which mammals such as horses, deer, elephants, cats and dogs began to dominate life on Earth.

Located in a remote area in Siberia, perhaps, most impressive of all is how Lake Baikal came to be. It is one of the few lakes formed through rifting. The lake is in fact, one of only two continental rifted valleys on our planet. Typically, “continental rift zones are long, narrow tectonic depressions in the Earth’s surface”, writes Hans Thybo, lead author of a paper on the subject. The Baikal rift zone developed in the last 35 million years, as the Amurian and Eurasian Plate pull away from one another. Eventually, the stretching of the Earth’s surface, at continental rifted margins, can lead to continental lithosphere splitting and the formation of new oceanic lithosphere. Alternatively, as is the case in Siberia, extensive sedimentary basins can be formed; bound by faults, they are known as grabens. It is by this process that Lake Baikal was formed and now houses around 20% of the world’s fresh water!

But this is not where the amazing facts about today’s Imaggeo on Monday’s picture end. The lake is the origin of the Angara River, along which you’ll find the manmade Bratsk Dam, the world’s second largest dam! The shoreline pictured in this photo by Jean- Daniel Paris, is from this impressive dam. Completed in 1964, this artificial reservoir is home to almost 170 billion cubic meters of water (equivalent to the volume held by 68 million Olympic sized swimming pools!).

However, it’s not the impressive water bodies in this inaccessible location in Siberia that are of interest to Jean-Daniel. In fact, this photograph was taken from a research aircraft, which flew over the region for an investigation that spanned a period of several years. Its aim was to measure how concentrations of CO2 and CO varied across the region. Acquiring this data would allow the team of scientist to better understand the sources of the gases, in this remote area of Russian, due to anthropogenic activities and biomass burning.

Reference

Thybo, H., Nielsen, C.A.: Magma-compensated crustal thinning in continental rift zones, Nature, 457, 873-876, doi: 10.1038/nature07688, 2009

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/.

Imaggeo on Mondays: An explosive cloud

Imaggeo on Mondays: An explosive cloud

One of the world’s most volcanically active regions is the Kamchatka Peninsula in eastern Russia. It is the subduction of the Pacific Plate under the Okhotsk microplate (belonging to the large North America Plate) which drives the volcanic and seismic hazard in this remote area. The surface expression of the subduction zone is the 2100 km long Kuril-Kamchatka volcanic arc: a chain of volcanic islands and mountains which form as a result of the sinking of a tectonic plate beneath another.  The arc extends from Hokkaido in Japan, across the Kamchatka Peninsula, through to the Commander Islands (Russia) to the Northwest. It is estimated that the Pacific Plate is moving towards the Okhotsk microplate at a rate of approximately 79mm per year, with variations in speed along the arc.

There are over 100 active volcanoes along the arc. Eruptions began during the late Pleistocene, some 126,000 years ago at a time when mammoths still roamed the vast northern frozen landscapes and the first modern humans walked the Earth.

Many of the volcanoes in the region continue to be active today. Amongst them is Karymsky volcano, the focus of this week’s Imaggeo on Mondays image. Towering in excess of 1500 m above sea level (a.s.l), the volcano is composed of layers of hardened lava and the deposits of scorching and fast moving clouds of volcanic debris knows as pyroclastic flows. You can see some careering down the flanks of the volcano in this image of the July 2004 eruption. The eruptive column is the result of a

“strong Vulcanian-type explosion, with the cloud quickly rising more than 1 km above the vent. The final height of the eruption cloud was approximately 3 km and in the image you can clearly see massive ballistic fallout from multiple hot avalanches on the volcanoes slopes,”

explains Alexander Belousov, a Senior Researcher at the Institute of Volcanology and Seismology in Russia and author of this week’s photograph.

 

USGS map of the Kuril-Kamchatka trench, showing earthquake locations and depth contours on downgoing slab. Credit: USGS, USGS summary of the 2013 Sea of Okhotsk earthquake, via Wikimedia Commons.

USGS map of the Kuril-Kamchatka trench, showing earthquake locations and depth contours on downgoing slab. Credit: USGS, USGS summary of the 2013 Sea of Okhotsk earthquake, via Wikimedia Commons.

If you pre-register for the 2015 General Assembly (Vienna, 12 – 17 April), you can take part in our annual photo competition! From 1 February 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/.

Imaggeo on Mondays: Landslide on the Cantabrian coastline

Shimmering blue seas, rocky outcrops and lush green hills sides; this idyllic landscape is punctuated by a stark reminder that geohazards are all around us. Irene Pérez Cáceres, a PhD student at the University of Granada (Spain) explains the geomorphology behind this small scale landslide on the Asturian coastline.

Landslide on the Cantabrian Sea. Credit: Irene Pérez Cáceres (distributed via imaggeo.egu.eu)

Landslide on the Cantabrian Sea. Credit: Irene Pérez Cáceres (distributed via imaggeo.egu.eu)

This picture was taken in May 2011 in the coast of Llanes (Asturias, Spain). I was living in Oviedo (Asturias, Spain) doing my Master in the structural geology of the Axial Zone of the Pyrenees. Thus, geomorphology and geohazards are not my specialty or area of expertise. However, the landslides are well known and studied in this region, and people from Asturias call them Argayos.

This argayo is situated in Niembru Mountain, over the San Antolín beach, constantly affected by waves and swell of tides of the Cantabrian Sea, and continuous rain typical in the region. It was defined as a rotational landslide with two fracture surfaces, possibly conjugated in wedge shape. It is approximately 50 meters high and 60 meters width at its base. The slide volume is calculated at 45000 m3. It is carved in quartzite altered by the water rain infiltration through crevices in the surface. The initial displacement was between 10 and 15 meters in the scar. Experts say this landslide is still active, moving and evolving continuously. It is an imminent risk for the swimmers, but it is very difficult to control it, due to the size and the slope, and the technical requirements to stabilize the rock. On the other side of this mountain, further landslides are evident, as a result of the building of a road.

These natural geomorphological processes are very common in the north of Spain, mainly in riverbeds, as well in other nearby beaches. The main causes are the abundant (and sometimes heavy) rainfall, the typically clay rich soils, steep slopes, building works that destabilize the slopes, and the absence of vegetation in some areas. They vary in in size and volume, and can sometimes have important material consequences and can pose a significant risk for the local inhabitants. The annual economic cost for repairing the damage caused by these processes is estimated to be 66 million of euros in this region.

Studies carried out in the Department of Geology of the University of Oviedo (Mª José Domínguez and her group), indicate that 70% of the landslides in Asturias happen when it rains over 200 mm during over a period of a minimum of three days. Research has also been carried out to try and predict when landslides might happen, examining numerous landslides over the last 20 years approximately. It seems that one conditioning factor is the exact location of new buildings, being that ancient constructions used to be in secure zones, probably because people observed more minutely to the nature, but the new ones are more vulnerable.

To conclude, detailed geological and geomorphological studies are always recommended to carry out before constructions. Thereby it is possible to minimise this common geohazard in Asturias.

By Irene Pérez Cáceres, PhD Student, Granada University.

 

If you pre-register for the 2015 General Assembly (Vienna, 12 – 17 April), you can take part in our annual photo competition! From 1 February 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/.

GeoEd: A risky business

In this month’s GeoEd post, Sam Illingworth explores the pitfalls of being a scientist in the public eye. Following the recent acquittal of 6 geoscientists on manslaughter charges after ‘failing’ to predict the 2009 L’Aquila earthquake, is it time we thought about improving how risk is communicated to the wider public?

At the beginning of November of this year, six Italian scientists were acquitted of manslaughter; an appeals court in L’Aquila (a medieval Italian city on the edge of the Aterno river) overturning the 2012 guilty verdicts that were originally cast against the researchers.

In their initial trial, the scientists were convicted of multiple manslaughter charges, by failing to predict the devastating earthquake, which struck at 03:32 CEST on 6 April 2009, and which was responsible for the deaths of 309 people. It has taken the past two years to acquit these six scientists, and the initial ramifications of the convictions were far reaching, with other researchers from across the globe wondering if a precedent had now been set, regarding liability for the conveyance of information.

Aerial view of the city of L'Aquila east-centre (Photo Credit: Public Domain, via Wikipedia.org)

Aerial view of the city of L’Aquila east-centre (Photo Credit: Public Domain, via Wikipedia.org)

Sadly, scientists are far from unaccustomed with judicial proceedings, from Galileo vs. the Catholic Church, to more recent examples of scientists being sued by a gym regarding injury rate statistics, or NASA being sued for trespassing on MARS. However, the recent allegations against the L’Aquila six (actually there were seven experts in total; more on this later), calls into question the fundamental belief system of accountability. If a building surveyor were to tell you that the foundations of your house were sound, yet you were later to find evidence of subsidence you would expect compensation from the surveyor. So why not also from the scientists, after all are they not too experts in their own field?

Well, for one thing, finding evidence for subsidence is far more of a precise art than trying to predict earthquakes. On the one hand you are looking for something that already exists, and on the other you are searching for something that may or may not be. In addition to this, surveyors are usually protected by professional indemnity insurance.

Are scientists adequately protected (Photo Credit: Sandstein via Wikimedia Commons)

Are scientists adequately protected (Photo Credit: Sandstein via Wikimedia Commons)

However, in the case of scientists communicating risk, is not being able to accurately predict an earthquake or a volcanic eruption really professional negligence, or is it simply to be expected given the impossibility of fully accurate predictions?

What is potentially worrying to scientists is that the line between professional negligence and unforeseen circumstance would appear to be very blurred indeed. Although, in some instances the distinction is far more clear-cut, for example the behaviour of the seventh member of the panel of experts in the L’Aquila case, Bernardo De Bernardinis. The then deputy director of the Civil Protection agency had, prior to the earthquake, advised locals to “sit back and enjoy a nice glass of Montepulciano” wine. Bernandinis was not acquitted, although his prison sentence was cut, from six to two years.

Although many might view Bernandinis as being guilty of nothing more than pompous over confidence, it is important to remember that as scientists we still have a role to inform the public as to the seriousness of any potential dangers, even if we are not ultimately to be held accountable for our inability to predict them. In other words, failing to predict a natural hazard (or other such incident) should not be seen as professional negligence, but failing to adequately inform the general public of the consequences of any potential threats, probably should be.

Of course, communicating risk goes well beyond natural disasters, and is something that many of us do when we talk about the effects of both current and predicted climate change. In these situations, scientists also regularly put themselves in the firing line, although this time often with regards to the media and pressure groups with an anti-climate change agenda.

One of the most well known examples of this was when a Competitive Enterprise Institute (CEI) analyst made the following, frankly horrific statement, about Penn State University climate researcher Michael Mann:

“Mann could be said to be the Jerry Sandusky of climate science, except that instead of molesting children, he has molested and tortured data in the service of politicized science.”

Dr Michael Mann: fighting the fakers (Photo Credit: Reason4Reason via Wikimedia Commons)

Dr Michael Mann: fighting the fakers (Photo Credit: Reason4Reason via Wikimedia Commons)

Dr Mann has subsequently sued the CEI, but such legal proceedings are both incredibly expensive and time consuming, and often represent a completely alien world to many scientists who are simply just doing their job.

In the US, scientists working for government or federal labs are now offered free legal counsel and support by the organization Protecting Our Employees Who Protect Our Environment (PEER). In addition to this, some scientific professions are now requiring their researchers to have professional indemnity insurance, for example in the UK, legislation was recently introduced that requires all health care scientists to have a professional indemnity arrangement in place, as a condition of their registration with the health & care professions council.

According to Jeff Ruch, the director of PEER, threatening scientists for their science “is a bully strategy,” and “bullies don’t like to be pushed back at.” Whilst the work of PEER and their contemporaries is admirable, is this a position that scientists should ever be finding themselves in? And is there anything that they could be doing to avoid such potential pitfalls?

In some cases, these pitfalls could be avoided by a more careful consideration of how to communicate risk, by explaining to the general public that there are many uncertainties associated with the calculations and predictions that are being made. However, I think that this is something that many scientists are already reasonably adept at, and if scientists are guilty of anything it is sometimes of being overcautious with their predictions, or of waiting to comment until they are absolutely 99.9% sure (with the obligatory 0.1% margin of error).

Media and science communication training can help scientists prepare for how to deliver their research and advice in potentially alien and hostile arenas, but there will always be instances where people have a set agenda to follow at any cost.

There may well be a public perception that scientists failing to predict natural disasters, or underdetermining a certain problem, are like the proverbial bad workmen who blame their tools. However, in trying to communicate risk I think that it might well be a case of “don’t shoot the messenger,” even if it turns out that they have no message to convey.

By Sam Illingworth, Lecturer, Manchester Metropolitan University

 

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