GeoLog

GeoLog

Educators: apply now to take part in the 2018 GIFT workshop!

Educators: apply now to take part in the 2018 GIFT workshop!

The General Assembly is not only for researchers but for teachers and educators with an interest in the geosciences also. Every year the Geosciences Information For Teachers (GIFT) is organised by the EGU Committee on Education to bring first class science closer to primary and high school teachers.

The topic of the 2018 edition of GIFT is ‘Major events that shaped the Earth’. This year’s workshop will be taking place on 9–11 April 2018 at the EGU General Assembly in Vienna, Austria.

Teachers from Europe and around the world can apply to participate in the 2018 edition of GIFT, and to receive a travel and accommodation stipend to attend the workshop, by November 15. Application information is available for download in PDF format, a document which also includes the preliminary programme of the workshop.

Not sure what to expect? More information about GIFT workshops can be found in the GIFT section of the EGU website. You can also take a look at a blog post about the 2015 workshop and also learn what the workshop is like from a teacher’s perspective here. You might also find videos of the 2017 workshop useful too.

 

Imaggeo on Mondays: A prehistoric forest

Imaggeo on Mondays: A prehistoric forest

This stunning vista encompasses the south-western wilderness of Tasmania as seen from the Tahune air walk 60 m above the Huon river valley. In front lies the beginning of a huge UNESCO World Heritage Site, covering almost a fourth of the area of Tasmania. The site mostly consists of a pristine, temperate rainforest of Gondwanan origin that is home to the tallest flowering trees in the world; Eucalyptus spp. reach up to 100 m height in this region.

“I have never tasted the sense of a more remote place than this one. Give me more,” says Vytas Huth, who captured this stunning shot.

Gondwana was a supercontinent, consisting of present day Africa, South America, India, Madagascar, Australia and New Zealand. It formed when the even larger supercontinent of Pangaea broke up 250 million years ago.

Slowly, Gondwana started to break apart too. India tore away first, followed by Africa and then New Zealand. By the end of the Cretaceous, 65 million years ago, only South America, Australia and Antarctica remained joined.  It took a further 20 million years before Australia and Antarctica separated.

By the time Australia started being pulled northwards, the first glaciers were forming on Antarctica, as it began freezing over. Atop the old rocks which made up its bulk, animals and plants of ancient origin, travel northwards with the Land Down Under.

Because India and Africa broke away from the supercontinent so early on, few hallmarks of ancient Gondwana wildlife are left in their present biodiversity. In contrast, Australia and Tasmania remained connected to Antarctica and South America much longer and there are clear similarities in species across these continents.

“Fossil evidence suggests that temperate rainforest once extended across Australia, Antarctica, South America and New Zealand around 45 million years ago. Such fossils and the surviving species in Tasmania provide evidence of the ancient link to Gondwana”, reports the Tasmania Parks & Wildlife Service.

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/.

 

Is it an earthquake, a nuclear test or a hurricane? How seismometers help us understand the world we live in

Is it an earthquake, a nuclear test or a hurricane? How seismometers help us understand the world we live in

Although traditionally used to study earthquakes, like today’s M 8.1 in Mexico,  seismometers have now become so sophisticated they are able to detect the slightest ground movements; whether they come from deep within the bowels of the planet or are triggered by events at the surface. But how, exactly, do earthquake scientists decipher the signals picked up by seismometers across the world? And more importantly, how do they know whether they are caused by an earthquake, nuclear test or a hurricane?  

To find out we asked Neil Wilkins (a PhD student at the University of Bristol) and Stephen Hicks (a seismologist at the University of Southampton) to share some insights with our readers.


Seismometers are highly sensitive and they are able to detect a magnitude 5 earthquake occurring on the other side of the planet. Also, most seismic monitoring stations have sensors located within a couple of meters of the ground surface, so they can be fairly susceptible to vibrations at the surface. Seismologists can “spy” on any noise source, from cows moving in a nearby field to passing trucks and trains.

A nuclear test

On Sunday the 3rd of September, North Korea issued a statement announcing it had successfully tested an underground hydrogen bomb. The blast was confirmed by seismometers across the globe. The U.S.  Geological Survey registered a 6.3 magnitude tremor, located at the Punggye-ri underground test site, in the northwest of the country. South Korea’s Meteorological Administration’s earthquake and volcano center also detected what is thought to be North Korea’s strongest test to date.

However they occur, explosions produce ground vibrations capable of being detected by seismic sensors. Mining and quarry blasts appear frequently at nearby seismic monitoring stations. In the case of nuclear explosions, the vibrations can be so large that the seismic waves they produce can be picked up all over the world, as in the case of this latest test.

It was realised quite early in the development of nuclear weapons that seismology could be used to detect such tests. In fact, the need to have reliable seismic data for monitoring underground nuclear explosions led in part to the development of the Worldwide Standardized Seismograph Network in the 1960s, the first of its kind.

Today, more than 150 seismic stations are operating as part of the International Monitoring System (IMS) to detect nuclear tests in breach of the Comprehensive Test-Ban Treaty (CTBT), which opened for signatures in 1996. The IMS also incorporates other technologies, including infrasound, hydroacoustics and radionuclide monitoring.

The key to determining whether a seismic signal is from an explosion or an earthquake lies in the nature of the waves that are present. There are three kinds of seismic wave seismologists can detect. The fastest, called Primary (P) waves, cause ground vibrations in the same direction that they travel, similar to sound waves in the air. Secondary (S) waves cause shaking in a perpendicular direction. Both P and S waves travel deep through the Earth and are known collectively as body waves. In contrast, the third type of seismic waves are known as surface waves, because they are trapped close to the surface of the Earth. In an earthquake, it is normally surface waves that cause the most ground shaking.

In an explosion, most of the seismic energy is released outwards as the explosive material rapidly expands. This means that the largest signal in the seismogram comes as P waves. Explosions therefore have a distinctive shape in the seismic data when compared with an earthquake, where we expect S and surface waves to have higher amplitude.

Forensic seismologists can therefore make measurements of the seismic data to determine whether there was an explosion. An extra indication that a nuclear test occurred can also be revealed by measuring the depth of the source of the waves, as it would not be possible to place a nuclear device deeper than around 10 km below the surface.

Yet while seismic data can tell us that there has been an explosion, there is nothing that can directly identify that explosion as being nuclear. Instead, the IMS relies on the detection of radioactive gases that can leak from the test site for final confirmation of what kind of bomb was used.

The figure shows (at the bottom) the seismic recording of the latest test in North Korea made at NORSAR’s station in Hedmark, Norway. The five upper traces show recordings at the same station for the five preceding tests, conducted by North Korea in 2006, 2009, 2013 and 2016 (two explosions in 2016). The 2017 test, is as can be seen from this figure, clearly the strongest so far. Credit: NORSAR.

When North Korea conducted a nuclear test in 2013, radioactive xenon was detected 55 days later, but this is not always possible. Any detection of such gases depends on whether or not a leak occurs in the first place, and how the gases are transported in the atmosphere.

Additionally, the seismic data cannot indicate the size of the nuclear device or whether it could be attached to a ballistic missile, as the North Korean government claims.

What seismology can give us is an idea of the size of the explosion by measuring the seismic magnitude. This is not straightforward, and depends on knowledge of exactly how deep the bomb was buried and the nature of the rock lying over the test site. However, by comparing the magnitude of this latest test with those from the previous five tests conducted in North Korea, we can see that this is a much larger explosion.

The Norwegian seismic observatory NORSAR has estimated a blast equivalent to 120 kilotons of TNT, six times larger than the atomic bomb dropped on Nagasaki in 1945, and consistent with the expected yield range of a hydrogen bomb.

Hurriquakes?

Nuclear tests are not the only hazard keeping our minds busy in the past few weeks. In the Atlantic, Hurricanes Harvey, Irma and Katia have wreaked havoc in the southern U.S.A, Mexico and the Caribbean.

Hurricanes in the Atlantic can occur at any time between June and November. According to hurricane experts, we are at the peak of the season. It is not uncommon for storms to form in rapid succession between August, September and October.

The National Hurricane Centre (NHC) is the de facto regional authority for producing hurricane forecasts and issuing alerts in the Atlantic and eastern Pacific. For their forecasts, meteorologists use a combination of on the ground weather sensors (e.g. wind, pressure, Doppler radar) and satellite data.

As hurricane Irma tore its way across the Atlantic, gaining strength and approaching the Caribbean island of Guadeloupe, local seismometers detected its signature, sending the global press into a frenzy. It may come as a slight surprise to some people that storms and hurricanes also show on seismometers.

However, a seismometer detecting an approaching hurricane is not actually that astonishing. There is no evidence to suggest that hurricanes directly cause earthquakes, so what signals can we detect from a hurricane? Rather than “signals”, seismologists tend to refer to this kind of seismic energy as “noise” as it thwarts our ability to see what we’re normally looking out for – earthquakes.

The seismic noise from a storm doesn’t look like distinct “pings” that we would see with an earthquake. What we see are fairly low-pitched “hums” that gradually get louder in the days and hours preceding the arrival of a storm. As the storm gets closer to the sensor, these hums turn into slightly higher-pitched “rustling”. This seismic energy then wanes as the hurricane drifts away. We saw this effect clearly for Hurricane Irma with recordings from a seismometer on the island of Guadeloupe.

What causes these hums and rustles? If you look at the frequency content of seismic data from any monitoring station around the globe, noise levels light up at frequencies of ~0.2 Hz (5 s period). We call these hums “microseism”. Microseism is caused by persistent seismic waves unrelated to earthquakes, and it occurs over huge areas of the planet.  One of the strongest sources of microseism is caused by ocean waves and swell. During a hurricane, swell increases and ocean waves become more energetic, eventually crashing into coastlines, transferring seismic energy into the ground. This effect is more obvious on islands as they are surrounded by water.

As the hurricane gets closer to the island, wind speeds dramatically increase and may dwarf the noise level of the longer period microseism. Wind rattles trees, telegraph poles, and the surface itself, transferring seismic energy into the ground and moving the sensitive mass inside the seismometer. This effect causes higher-pitched “rustles” as the centre of the storm approaches. Gusts of wind can also generate pressure changes inside the seismometer installation and within the seismometer itself, generating longer period fluctuations.

During Hurricane Irma, a seismic monitoring station located in the Dutch territory of St. Maarten clearly recorded the approach of the storm, leading to an intense crescendo as the eyewall crossed the area. As the centre of the eye passed over, the seismometer seems to have recorded a slightly lower noise level. This observation could be due to the calmer conditions and lower pressure within the eye. The station went down shortly after, probably from a power outage or loss in telemetry which provides the data in real-time.

Seismometers measuring storms is not a new observation. Recently, Hurricane Harvey shook up seismometers located in southern Texas. Even in the UK, the approach of winter storms across the Atlantic causes much higher levels of microseism.

It would be difficult to use seismometer recordings to help forecast a hurricane – the recordings really depend on how close the sensor is to the coast and how exposed the site is to wind. In the event of outside surface wind and pressure sensors being damaged by the storm, protected seismometers below the ground could possibly prove useful in delineating the rough location of the hurricane eye, assuming they maintain power and keep sending real-time data.

At least several seismic monitoring stations in the northern Antilles region were put out of action by the effects of the Hurricane. Given the total devastation on some islands, it is likely that it will take at least several months to bring these stations back online. The Lesser Antilles are a very tectonically active and complex part of Earth; bringing these sensors back into operation will be crucial to earthquake and volcano hazard monitoring in the region.

By Neil Wilkins (PhD student at the University of Bristol) and Steven Hicks (a seismologist at the University of Southampton)

References and further reading

GeoSciences Column: Can seismic signals help understand landslides and rockfalls?

NORSAR Press Release: Large nuclear test in North Korea on 3 September 2017

The Comprehensive Nuclear-Test-Ban Organization Press Release: CTBTO Executive Secretary Lassina Zerbo on the unusual seismic event detected in the Democratic People’s Republic of Korea

First Harvey, Then Irma and Jose. Why? It’s the Season (The New York Times)

NOAA  National Hurricane Center

IRIS education and outreach series: How does a seismometer work?

Academia is not the only route: exploring alternative career options for Earth scientists

Academia is not the only route: exploring alternative career options for Earth scientists

With more PhD and postdoc positions than there are tenured posts, landing a permanent job in academia is increasingly challenging. For some, years of funding and position uncertainty, coupled with having to relocate regularly is an unwelcome prospect. A changing job market also means that aspiring to the traditional, linear career path might be an unrealistic expectation. Skills acquired by those striving for an academic career (analytical skills, time and project management, persistence – writing a thesis requires it by the bucketload!) are highly valued in other job sectors too.

During a short course at the 2017 General Assembly, a panel of current and former geoscientists discussed their experiences in jobs both inside and outside academia.  They offered tips for how to pursue their careers paths and what skills served them best to get there.

In this blog post we profile each of their jobs and offer some of the highlights from the advice given during the session at the conference.


During the panel discussion Victoria stressed the importance of building a strong professional network, both inside and out of academia.

Victoria O’Connor (Technical Director at Petrotechnical Data Systems)

Victoria gained an undergraduate master degree in geology from the University of Liverpool in 2007. Since then, her career has focused around the oil industry, but has seen twists and turns, which have relied heavily on her building a varied skill set.

For almost six years after graduation, Victoria worked at Rock Deformation Research Ltd (RDR),  a spin out company from the University of Leeds, which was eventually acquired by Schlumberger. She held various roles throughout her time there, eventually becoming Vice President. The role relied heavily on her technical expertise as a structural geologist, as well as people management and organisational skills. In 2013, she moved to The Netherlands to work the Petrel technology team at Shell, where she managed various geoscience software development projects.

Her experience eventually enabled her to set up her own geoscience consulting company which was acquired by the PDS Group, through which she now manages the Geoscience products and services division, leading a 40 strong team of geoscientists and scientific software developers, developing cutting edge technologies for the oil and gas industry in collaboration with various academic institutions. In addition she also holds a visiting researcher position at the University of Leeds where she provides teaching and consultancy support. In addition, she also edits the European region AAPG newsletter.

During the panel discussion, Victoria stressed the importance of building relationships and developing a network of contacts. The benefits of building a strong professional network, both inside and out of academia are far reaching: job opportunities, joint collaborations, career development prospects. In her current role, she is developing technology with academic partners she first met over ten years ago at the University of Leeds.


getting on the career To get on the career ladder make sure you have a well written cover letter and CV, says Philip.

Philip Ball (Strategic Planning and Optimization Team & Geological Specialist [Rifted Margins] at Saudi Aramco)

Philip’s career certainly falls in the windy road category, rather than the linear path. It has involved a number of switches between industry and academic positions which have taken him all over the globe. His positions have always had an oil industry focus. He has lived through a number of market slumps, resulting in redundancies and an uncertain career path at times.

During the panel discussion Philip, highlighted adaptability and flexibility (skills certainly gained during research years) as a key to his success. Landing his first position was partly down to his willingness to be flexible.  In addition to being proactive, publishing, attending conferences and meetings, maintaining a network, never giving up is also critical. For example, he applied three times to Statoil between 2013 and 2015 before he managed to get an interview.

Before progressing onto a PhD, Philip enjoyed a short stint at the British Geological Survey and was a geologist for Arco British Ltd. Since gaining his PhD from Royal Holloway, University of London in 2005, Philip has held a number of positions at oil companies, including StatOil, ConocoPhillips, ONGC Videsh and Saudi Aramco.

His top tips, for getting on the career ladder is to make sure you have a well written cover letter and CV. This is critical whether applying for a student travel grant, research position or a position outside of the academic realm. Also do your research and do not expect chances to come to you. Use and visit the job boards online regularly to find positions in geoscience or other fields.


A career in the publications industry is a popular choice among researchers, like Xenia.

Xenia van Edig (Business Development at Copernicus.org)

Researchers are necessarily familiar with the world of academic publication (for more tips on how journal editors work take a look at this post we published recently), so it is hardly surprising this ends up being the chosen career of many former scientists.

Xenia Van Edig is one such example. Following an undergraduate in geography and PhD  in agricultural sciences at Georg-August-Universität-Göttingen, Xenia took a sidestep into the world of scientific coordination and management before starting her role at Copernicus (publishers of open access journals – including all the EGU publications – and conference organisers).

Project management was a skill set Xenia developed throughout her time as a junior researcher. It has been a pillar stone of her career outside of academia too.


Robert is an example of how a a hobby can become a new career direction.

Robert McSweeney (Science Editor at Carbon Brief)

Robert holds an MEng in mechanical engineering and an MSc in climate change. He worked for eight years as an environmental scientist for Atkins, a global design, engineering and project management firm.

For the past three years he’s been working as a science writer for Carbon Brief  – a website covering the latest developments in climate science, climate policy and energy policy – where he is now science editor. The role relies heavily on Robert’s communications skills, which scientists hone throughout their research career in the form of presentations at conference and to peers.

Robert highlighted how a hobby – in this case, writing – can become a new career direction. He also emphasised that scientists have a lot of opportunities to get involved with communicating their research, and commenting on others’, through blogs, Twitter, and developing extra materials to publish with new papers.


You don’t necessarily have to stick within your original field of expertise

Steven Gibbons (Senior Research Geophysicist at NORSAR)

Perhaps the best hybrid career for a researcher is to be able to continue to investigate, but not necessarily in an academic setting. It’s a nice compromise for those seeking a little more stability than life at traditional research institution might offer. But the notion shouldn’t be viewed with rose tinted glasses either: being an industry/foundation based scientists might mean less independence when it comes to selecting research topics and, often, securing funding is still an important part of the equation.

Nevertheless, it is can be a rewarding career which gives insights into a more commercial mindset and which draws on skills gain throughout academic research years, as Steven Gibbons described during the short course in April.

Crucially, his career trajectory highlights that you don’t necessarily have to stick within your original field of expertise. Steven has a PhD in core geodynamics and the Earth’s magnetic field, but now works as a geophysicist within the programme for Array Seismology and Test-Ban-Treaty Verification at NORSAR.

Steven has an undergraduate and PhD from the University of Leeds and has been working for NORSAR since 2002.


The EGU’s 2018 General Assembly, takes place in Vienna from 8 to 13 April, 2018. For more news about the upcoming General Assembly, you can also follow the offical hashtag, #EGU18, on our social media channels.

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