23 December 2015

23 December: Deep into Earth

Geophysics

What triggers earthquakes, volcanic eruptions and tsunamis? What happens when Earth’s massive continental plates move against one another? Today’s researcher – Professor Hans Thybo – is a fountain of knowledge on the subject, has travelled widely and has even made a few remarkable discoveries.

Ever since humans began questioning their existence, the Earth’s interior and the forces and dynamics within it have played a central role in human consciousness, in mythology and religion among other contexts. In Medieval Europe, it was believed that Iceland’s Hekla volcano was the actual “Gateway of Hell”. Ludvig Holberg dealt with the topic in his 1741 satirical novel, “Niels Klim’s Underground Travels”, in which a student falls into a deep hole and discover an entirely different world beneath the Earth’s surface.

Technique and fantasy

Curiosity about the Earth’s interior grew during the 19th Century as technologies emerged and possibilities became infinite. Such was the case in relation to space in general and rocket travel to the Moon, as well as with regards to expeditions to the centre of planet Earth. And of course, this fantasy was helped along by Jules Verne’s 1864 science fiction novel, “Journey to the Centre of the Earth”. In it, humans hope to journey to the Earth’s core and study new and unknown territories. It is quite funny that the novel’s main characters must first ascend Our Saviour’s Church in Copenhagen to gain control over their dizziness, before setting a course towards the Earth’s interior, the entrance to which is – of course – in Iceland.

Despite the many fantasies, Denmark has played a large role in studying inner Earth and its dynamics. For example, in 1936, the now famous Danish seismologist and geophysicist Inge Lehmann discovered that the Earth’s core is not just a molten sphere, but that a solid inner core exists and revolves around itself. Twenty years passed before she attained recognition for her theories.

A widely-travelled gentleman

Today’s researcher, Hans Thybo, is also recognized internationally. The 61-year-old professor and geophysicist is based at the Department of Geosciences and Natural Resource Management. Thybo heads the DanSeis Center which studies one of geoscience’s great mysteries: to find out if certain types of molten rock channels, known as mantle plumes, exist and stretch from the Earth’s molten core to its surface.

Thybo and others’ research into the Earth’s processes is directly related to our overall understanding of how the continents and oceans came to be. And a great deal of knowledge remains to be generated. Despite the fact that the Earth is roughly 13,000 kilometres in diameter, the distance between Denmark and New Zealand, for example, is 18,000 km.

Professor Hans Thybo on his work:

“I research processes in the Earth’s interior that influence the formation of various tectonic structures, such as rift zones. When the Earth’s surface cracks in rift zones, deep fissure structures are created that become filled with sedimentary and volcanic layers over time, structures that can be up to 25 kilometres thick. These studies have lead to various fieldwork locations in Siberia (the Baikal Rift Zone), East Africa (the East African Rift Zone in Kenya and Ethiopia), the United States (the Rio Grande Rift), Europe (rift zones around the Rhine and North Sea’s Central Graben) and Ukraine (the Dnieper-Donetsk rift). We study rift zones that continue to be active, as well as those that have completed their development.”

But as everyone knows, the Earth’s forces are far from a state of rest. Thybo continues:

“It is suspected that some rift zones may lead to the creation of new oceans if the processes continue to develop for long enough. The North Atlantic was created by such processes. 400 million years ago, the land areas that are now North America and Europe collided. This lead to the formation of a mountain range of comprable size to the Himalayas. The mountain range eventually collapsed after the collision and the Earth’s crust then “stretched” for 200-250 million years, during which time a number of local rift zones were created. Roughly 60 million years ago, the first of these stretches became the North Atlantic Ocean. New ocean bottom crust is constantly being formed along the Mid-Atlantic Ridge, just as North America and Europe continue to spread from one another at a pace of 2 centimetres per year.

With regards to Scandinavia, Iceland was born upon the Mid-Atlantic Ridge just 30 million years ago. The island was created from the same types of volcanic action that occurs along the ridge stretching from the Arctic south to Antarctica. Our group researches the processes that lead to the creation of the oceans as well as Iceland. We also attempt to explain why there are mountain chains around the entire North Atlantic.”

For the layperson, Thybo’s research may seem like pure theory and without any practical or economic significance beyond serving to understand the forces stirring within our Earth, forces which occasionally express themselves as volcanic eruptions, earthquakes or tsunamis.

 “As mentioned, my research primarily contributes to our understanding of the Earth’s development. The thread running through it all is that we should improve our knowledge about the processes that create and develop our lithosphere, the place where we source a great many natural resources to build the foundations for our modern society develops. Our research creates a foundation for the improved ability to predict the presence of a number of resources including oil and gas, diamonds and other precious stones, and a range of other raw materials. Throughout my career, I have worked with hundreds of researchers – and in particular, students - from far and near. I am currently working with a number of bachelor’s students to understand the development of the oceanic crust. It seems as if the student projects will lead to a critical understanding of the ocean depths that will force us to reconsider the current understandings of how the oceans developed,” underscores today’s researcher.