GeoLog

seismology

Weathering the storm from a research vessel

Weathering the storm from a research vessel

Fieldwork can take geoscientists to some of the most remote corners of the Earth in some of the harshest conditions imaginable, but stories from the field hardly make it into a published paper. In this blog post, Raffaele Bonadio, a PhD student in seismology at the Dublin Institute for Advanced Studies in Ireland, shares a particularly formidable experience in the field while aboard a research vessel in the North Atlantic Ocean.  

We knew it would be stormy that night. At the previous evening’s briefing, the captain of the ship, composed and collected, notified us that we needed to make a diversion from the planned route to avoid getting too close to the eye of the storm, “We’ll slow down the vessel…” “kind of five metres swell expected”. He was calm and comfortable. The crew members were calm and comfortable. We, the guest scientists, were not.

Why were we in the middle of the ocean?

I was part of a team of researchers from the Dublin Institute for Advanced Studies working on the project SEA-SEIS (Structure, Evolution and Seismicity of the Irish offshore). Our task was to deploy a suite of seismometers on the bottom of the North Atlantic Ocean from our research vessel, the RV Celtic Explorer, to investigate the geological evolution of the Irish offshore.

A map of the North Atlantic Ocean, showing the locations of seismometers deployed by the team’s research vessel, the RV Celtic Explorer. Credit: Raffaele Bonadio

Why study the Irish offshore?

The tectonic plate that Ireland sits on was deformed and stretched to form the deep basins offshore. The plate then broke, and its parts drifted away from each other, as the northern Atlantic Ocean opened. Hot currents in the convecting mantle of the Earth caused volcanic eruptions and rocks to melt 50-100 km below the Earth’s surface. These hot currents may have come from a spectacular hot plume rising all the way from the Earth’s core-mantle boundary (at 2891 km depth) to just beneath Iceland.

What do ocean bottom seismometers do?

Ocean bottom seismometers record the tiny vibrations of the Earth caused by seismic waves, generated by earthquakes and ocean waves. As the waves propagate through the Earth’s interior on their way to the seismic stations, they accumulate information on the structure of the Earth that they encounter. Seismologists know how to decode the wiggles on the seismograms to obtain this information. With this data, they can do a 3D scan (tomography) of what’s inside the Earth.

One of the research team’s seismometers being dropped into the North Atlantic Ocean. The instruments sink to the bottom of the ocean, where they measure the Earth’s movement. Credit: SEA-SEIS Team

In this project, we want to better understand how the structure of the tectonic plate varies from across the North Atlantic and what happens beneath the plates. And is there an enormous hot plume beneath Iceland, responsible for the country’s volcanoes today and the formation of Giant’s Causeway in Ireland? This is what we hope we will find out!

Experiencing an ocean storm

We were aboard the ship about 9 days and had just deployed “Ligea”, the 14th seismometer before the captain had notified us that a storm was heading our way.

While we were told in advance of the approaching storm, there was no way we could have imagined what it would be like to be in the middle of a stormy ocean. I had only heard some stories and I didn’t fully believe them…

I was awakened by the sound of my table lamp smashing on the ground, even the 15 cm protection edge around the table couldn’t help. The closet door opened and hit the wall. I managed not to fall off the bed, pointing my legs and make a crack with my back. I heard one of my colleagues laughing in the next cabin after a loud thud. “Did he just fall off the bed?” I thought to myself – his laugh did sound a bit of hysterical.

I realized a big wave had crashed on the side of the ship. I couldn’t believe that water and metal crashing together could make such a harsh bang. The previous evening was a continuation of bangs, splashes, sprinkles, bloops, clangs, and creaks … but even with all these noises and disturbances, I managed to sleep, exhausted from dizziness and sea-sickness.

I checked the clock on the wall: it was 3:20 in the morning. I looked at the porthole, due to the vertical movement my cabin was underwater half of the time. I walked through the cabin, trying to reach the toilet. “Oh, I wish they made the cabin smaller! I can’t reach both walls with my arms,” I said to myself. I opened the tap to refresh my face, the flowing water danced right and left across the basin. I then climbed up to the deck, I had to literally climb up the stairs. Up there I couldn’t see anything but darkness; I couldn’t see the boundary between the sky and the sea.

More than a week had passed since our departure, yet my body had still not adapted to this incessant movement. My eyes could not follow my body and my stomach did not react well, I couldn’t see anymore what was horizontal and what wasn’t. However, I wasn’t even scared, I believed nobody on the ship was (or is it only that I wanted to believe this?). It wasn’t fear, but rather an unceasing uncomfortable feeling: I knew I was more than 900 km from any dry land, in the middle of the North Atlantic Ocean, on a 66 m long vessel; I knew the captain and the crew were working hard to take us far from the storm. I was not scared…

In a few hours we were planning to deploy an ocean bottom seismometer, a very sophisticated device that is able to operate at huge pressures at the bottom of the ocean; released from the ship it would sink and install itself on the seafloor 4 km under the surface of the waves. In other words, a 200 kg ‘little orange elephant’, as the students who supported us from land every day liked to call it! “Will we be able to deploy? Will we be able not to crash the instrument on the sides? Will we instead be able to keep our balance and walk up to the deck?”

“Yes, we will.”

How did this look like? Find out more in this video:

 

So, what did we accomplish?

As part of the SEA-SEIS project, led by Dr. Sergei Lebedev, our research team successfully deployed 18 seismometers at the bottom of the North Atlantic Ocean. The network covers the entire Irish offshore, with a few sensors also in the UK and Iceland’s waters. The ocean-bottom seismometers were deployed between 17 September and 5 October, 2018, and will be retrieved in April of 2020.

To find out more about the SEA-SEIS Projects, have a look at SEA-SEIS or check out our introductory video.

By Raffaele Bonadio, Dublin Institute for Advanced Studies, Ireland

Imaggeo on Mondays: The ash cloud of Eyjafjallajökull approaches

Imaggeo on Mondays: The ash cloud of Eyjafjallajökull approaches

This photo depicts the famous ash cloud of the Icelandic volcano Eyjafjallajökull, which disrupted air traffic in Europe and over the North Atlantic Ocean for several days in spring 2010. The picture was taken during the initial phase of the eruption south of the town of Kirjubæjarklaustur, at the end of a long field work day. Visibility inside the ash cloud was within only a few metres.

The eruption was preceded by years of seismic unrest and repeated magma intrusions. A first effusive fissure opened outside the ice shield of the volcano at the end of March 2010, followed by an explosive eruption in the main crater of the volcano in April 2010.

Iceland was well prepared for the eruption – the rest of the world obviously was not. The region around Eyjafjallajökull is sparsely populated, residents were prepared days before the eruption and the evacuation went smoothly. However, the grain size of the ejected volcanic ash was fine enough so that the unfavourable and unusual wind direction during these days transported the ash all the way to Europe and led to air space closures almost all over the continent.

By Martin Hensch, Nordic Volcanological Center, University of Iceland (now at Geological Survey of Baden-Württemberg, Germany)

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/.

November GeoRoundUp: the best of the Earth sciences from around the web

November GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, major geoscience headlines, as well as unique and quirky research, this monthly column aims to bring you the latest Earth and planetary science news from around the web.

Major stories

Earth’s red and rocky neighbor has been grabbing a significant amount of attention from the geoscience media this month. We’ll give you the rundown on the latest news of Mars.

The NASA-led InSight lander, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, touched down on the Red Planet’s surface last week, causing the space agency’s Jet Propulsion Laboratory (JPL) control room to erupt in applause, fist pumps, and cool victory handshakes.

The lander, equipped with a heat probe, a radio science instrument and a seismometer, will monitors the planet’s deep interior. Currently, no other planet besides our own has been analysed in this way.

While scientists know quite a bit about the atmosphere and soil level of Mars, their understanding of the planet’s innerworkings, figuratively and literally, only scratches the surface. “We don’t know very much about what goes on a mile below the surface, much less 2,000 miles below the surface down to the center,” explains Bruce Banerdt, a scientist at JPL, to the Atlantic.

By probing into Mars’ depths, researchers hope the mission gives insight into the evolution of our solar system’s rocky planets in their early stages and helps explain why Earth and Mars formed such different environments, despite originating from the same cloud of dust.

“Our measurements will help us turn back the clock and understand what produced a verdant Earth but a desolate Mars,” Banerdt said recently in a press release.

The InSight lander launched from Earth in May this year, making its way to Mars over the course of seven months. Once reaching the planet’s upper atmosphere, the spacecraft decelerated from about 5,500 to 2.4 metres per second, in just about six minutes. To safely slow down its descent, the lander had to use a heatshield, a parachute and retro rockets.

“Although we’ve done it before, landing on Mars is hard, and this mission is no different,” said Rob Manning, chief engineer at JPL, during a livestream. “It takes thousands of steps to go from the top of the atmosphere to the surface, and each one of them has to work perfectly to be a successful mission.”

This artist’s concept depicts NASA’s InSight lander after it has deployed its instruments on the Martian surface. Credit: NASA/JPL-Caltech

The InSight lander is currently situated on Elysium Planitia, a plane near the planet’s equator also known by the mission team as the “biggest parking lot on Mars.” Since landing, the robot has taken its first photos, opened its solar panels, and taken preliminary data. It will spend the next few weeks prepping and unpacking the instruments onboard.

The devices will be used to carry out three experiments. The seismometers will listen for ‘marsquakes,’ which can offer clues into the location and composition of Mars’ rocky layers. The thermal probe will reveal how much heat flows out of the planet’s interior and hopefully show how alike (or unalike) Mars is to Earth. And finally, radio transmissions will demonstrate how the planet wobbles on its axis.

In other news, NASA has also chosen a landing site for the next Mars rover, which is expected to launch in 2020. The space agency has announced that the rover will explore and take rock samples from Jezero crater, one of the three locations shortlisted by scientists. The crater is 45 kilometres wide and at one point had been filled with water to a depth of 250 metres. The sediment and carbonate rocks left behind could offers clues on whether Mars had sustained life.

What you might have missed

By analysing radar scans and sediment samples, a team of scientists have discovered a massive crater, hidden underneath more than 900 metres of ice in northwest Greenland. After surveying the site, scientists say it’s likely that a meteorite created the sometime between 3 million and 12,000 years ago.

The depression under Hiawatha Glacier is 31 kilometres wide, big enough to hold the city of Paris. At this size, the crater is one of the top 25 largest craters on Earth; it’s also the first to be found under ice. An impact of this size significant mark on the Earth’s environment. “Such an impact would have been felt hundreds of miles away, would have warmed up that area of Greenland and may have rained rocky debris down on North America and Europe,” said Jason Daley from Smithsonian Magazine.

Links we liked

The EGU Story

This month, we have announced changes to the EGU General Assembly 2019 schedule, which aim to give more time for all presentation types. Check our news announcement for more information. In other news, we have opened applications to the EGU General Assembly 2019 mentoring programme, and are advertising a job opportunity for geoscientists with science communication experience to work at the meeting.

Also this month, we opened the call for applications for EGU Public Engagement Grants, and have announced the creation of the EGU Working Group on Diversity and Equality. Finally, we’ve published a press release on a new study that looked into whether data on seabird behavior could be used to track the ocean’s currents.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

NASA’s InSight mission: detecting ‘earthquakes*’ on the surface of Mars

NASA’s InSight mission: detecting ‘earthquakes*’ on the surface of Mars

In three days’ time, NASA’s InSight Lander is expected to plunge through Mars’ atmosphere before parachuting down to a controlled landing on the flat plains of the Elysium Planitia.

Once the dust has settled, a solar powered robotic arm will painstakingly unload the precious instruments stored onboard onto the planet’s surface, carefully guided by scientists back on Earth.

This is an illustration showing a simulated view of NASA’s InSight about to land on the surface of Mars. (Credit: NASA/JPL-Caltech)

These instruments are designed to penetrate further into Mars’ subterranean secrets than any mission before. While previous Martian landers have monitored the planet’s surface and atmosphere, the goal of InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is to explore Mars’ interior using three specialised tools.

These include a heat probe which will measure the heat flow near to the surface, a radio science instrument which will measure how Mars wobbles on its axis, and a seismometer which will tell us about Mars’ deep interior. Scientists hope this will lead to new information on the formation of the planets in our solar system, perhaps even illuminating more detail on how our own planet came about.

Seismometers detect seismic waves, vibrations that travel through the ground after an event such as fault movement or meteorite impact. The type of wave and the speed at which it travels can provide important details about the material through which it moves. On Earth, a global network of seismometers has provided vital information about the structure of the planet’s core and mantle.

Robert Myhill, a seismologist at the University of Bristol, is part of a large international team of scientists who have been preparing for data returned by InSight’s seismometers (known as SEIS). Until recently, Myhill has been investigating how SEIS will be affected by Mars’ regolith (its shallow soil surface)[1].

Now that SEIS is en route to its Martian home however, Myhill and colleagues are getting ready for the next phase: receiving the data. “We hope to be able to use the waveforms from marsquakes and/or impacts to image the interior structure of the planet for the first time, including the thickness and structure of the crust, and the composition of the mantle and core,” Myhill explains.

“We’ve also been investigating how we can combine the geophysical data returned by InSight with existing geochemical data to tell us about the history of Mars and the continuing evolution of the planet’s deep interior.”

The data they will receive comes from two different types of sensors, a ‘very-broad-band’ (known as ‘VBB’) seismometer and three tiny short-period seismic sensors which are about the size of a Euro coin. The different sensors can detect various types of seismic wave, depending on the size and location of the seismicity.

Animation of InSight deploying it’s seismometer. (Credit: NASA/JPL-Caltech)

Gathering the information needed to achieve the mission’s goals presents numerous challenges. For starters, unlike Earth, which has a network of seismometers that can be used together, InSight will be the only active geophysical station on the Red Planet. Two previous seismometers, mounted on NASA’s Viking Landers in the 1970s, experienced technical faults and design limitations and are no longer in action. As a result, researchers have had to come up with novel ways to gather information from the lone InSight lander [2] [3].

The mission’s designers have also developed new technology to reduce noise and ensure the equipment can operate in Mars’ harsh environment. The seismometer will be mounted on a levelling system close to the Martian surface to minimise tilt and reduce the effect of wind. Once levelled, the lander’s robotic arm will place a wind and thermal shield over the top of the instruments, sheltering the sensitive instruments from extreme temperatures and buffeting by the Martian winds.

Despite the increased protection afforded by the wind and thermal shield, there remain challenges for InSight. “We hope that during the lifetime of the mission, we don’t have a prolonged dust-storm. Although InSight would not be damaged by such an event, it does need solar energy for all its instruments and for data transmission,” said Myhill.

NASA’s InSight mission tests an engineering version of the spacecraft’s robotic arm in a Mars-like environment at NASA’s Jet Propulsion Laboratory. (Credit: NASA/JPL-Caltech)

From 26 November, he and the others involved must wait with bated breath to see their hard work come to fruition. “We should receive the first data from the instrument deck not long after landing, but full deployment of SEIS (including the wind and thermal shield) is not scheduled until early January 2019,” he explains.

“The timing of first results really depends on the level of seismicity, which is currently very poorly known. In fact, determining the rate of seismic energy generation is one of the primary goals of the InSight Mission. But of course, we’re all hoping to see something soon after deployment.”

For the most up to date information on the mission, as well as more details in the lander’s other exciting capabilities see NASA’s InSight website.

*Astute readers of this blog may have noticed the error in the title. There is no such thing as an earthquake on Mars… instead InSight will be monitoring ‘marsquakes’.

By Keri McNamara, freelance science writer

Keri McNamara is a freelance writer with a PhD in Volcanology from the University of Bristol. She is on twitter @KeriAMcNamara and www.kerimcnamara.com.

References

[1]                      https://link.springer.com/article/10.1007/s11214-018-0514-5

[2]                      https://www.sciencedirect.com/science/article/abs/pii/S001910351400582X

[3]                      https://www.sciencedirect.com/science/article/pii/S0031920116300875?via%3Dihub