Prof. Yogeshwar: From Cologne to RWTH via Namibia

  Copyright: © P. Yogeshwar

Dear Dr. Yogeshwar,

Welcome to RWTH. Starting in the summer semester of 2022, you will represent the teaching and research field of "Computational Geoscience and Reservoir Engineering" or, with a new title, "Geophysical Imaging and Monitoring" in teaching and research for at least one year as a substitute professor.

  Copyright: © P. Yogeshwar

What focal points will you bring to teaching and research in Aachen?

My main areas of research are electrical and electromagnetic induction methods to explore the earths interior from shallow depths of a few meters down to several hundred meters. The key physical parameter for these methods is the subsurface electrical conductivity. Naturally, I am very most enthusiastic about the methods that I am highly specialized in. So – besides teaching classical geophysical methods, I like to focus more on electromagnetic induction methods.

Of course, I would highly appreciate to contribute and also benefit from synergies and a strong network in the field of earth sciences at the RWTH. Over the past years, I have been quite intensely involved in projects and campaigns for various prospects - for example since 2014 in a BMBF funded project on deep mineral exploration using ground-based and new semi-airborne electromagnetic techniques; but also in general geological targets for the detection of optimal coring sites, for example in the Azraq basin in Jordan, the Atacama desert in Chile and also in the Namib Desert. Actually, all these projects were part of the former CRC-806 and the CRC-1211. Both were established in Cologne and the ABC/J-Geoverbund – so strongly linked to RWTH Aachen via researchers and their sub-projects. Other projects focused on environmental issues such as groundwater contamination. Besides collecting data over interesting and challenging sites at some beautiful place in this world, a big part – actually the major part - of my work is more methodological, for example application and development of interpretation schemes for geophysical data

Recently, we were already brainstorming a few ideas for ongoing projects in Aachen, where electromagnetic methods may contribute already in a short term. But, lets see how things unfold.

  Copyright: © P. Yogeshwar

You completed your diploma (thesis topic: "Groundwater contamination near Roorkee/India: 2D joint inversion of radiomagnetotellurics and DC geoelectrical data") and your doctorate on "A resistivity-depth model of the central Azraq basin area, Jordan: 2D forward and inverse modelling of time domain electromagnetic data" in 2010 and 2014, respectively, at the University of Cologne. What fascinates you about geophysics?

That is an easy one. I do have a strong passion for traveling and also to fully focus my energy on one goal. I find it always an immense challenge to get a new project going from the initial planning stage until you are finally in the field and set up the first loggers and take the first recordings. For me this is always an extremely exciting process. And mostly it has been a very rewarding process, because it really demands full effort and you don‘t know if all the pre-modeling studies were correct and all the planning sufficient. But, the moment you have the first data analyzed in the field and it is meaningful – it is just tremendously rewarding and relieving.

Besides the adventure aspect, for me the fascination is really the multi-layered wide range of working and research areas. Geophysics covers such a wide span from the inner earth to outer space, but already only applied Geophysics touches upon a huge variety of interesting questions. Many of these questions are also relevant for society and humanity. For me, it is somehow the combination of strongly focused theoretical work- possibly getting lost behind the computer screen and then the exciting practical work – getting out for new adventures. When I was studying physics, I did not really see myself only working in a lab. One day I went to see the geophysics institute in Cologne and walked across an advertisement poster with a picture of Merapi volcano in Indonesia stating something like „You are interested in exciting research and questions related to processes in the earth?“. That somehow resonated with me and I found that I really enjoy the the earth as the lab. From there on things just unfolded and I was also lucky and extremely privileged to be involved in numerous exciting projects in many parts of the world.


Since completing your doctorate, you have been working in Prof. Tezkan's "Applied Geophysics" group at the Institute of Geophysics and Meteorology at the University of Cologne. What impression have you been able to gain of the geosciences at RWTH Aachen University from Cologne in the ABC/J geo association?

Actually, since many years I do benefit from the strong research network within the ABC/J Geoverbund. As said, I was (and still I am) lucky to be part of two large CRCs. Already my PhD in Jordan was within the CRC-806 and was linked to Aachen. In the current CRC-1211, for example, I am linked to Aachen via two sub-projects. In one sub-project we want to explore coastal alluvial fans in Chile to learn more about there internal architecture, deposition volume and their history. Within the CRC, we used to have shared colloquiums, graduate schools or integrated research training groups, in which different researchers would present there actual work. The variety of research activities in earth sciences at the RWTH did impress me.

  Copyright: © M. Melles and P. Yogeshwa

You are currently preparing a field trip to Namibia. Where exactly will the stay take you and what exactly are you researching on site?

We visited two sites – the approximately 4-5 million year old Roter Kamm impact crater and the Aurus clay pan. Both are located in Southern Namibia inside the Sperrgebiet. I guess, this is one of the most remote places on earth. It took us more than one year of intense preparations and we really had extensive delays. But finally we were able to take-off. For the survey, we were a large team of 15 members from the Institute of Geology and Mineralogy, the institute of Geophysics and Meteorology in Cologne, our colleagues from the TUBAF in Freiberg plus our collaborators from the Geological Survey and the University of Namibia. For 22 days, we were living in a camp close to the Roter Kamm, were cooking on fire and gas, sleeping in tents and working outside in the field.

We were using a bunch of different geophysical methods to optimally explore both sites from shallow depth of approximately 5 m down to roughly 600 m. Two electromagnetic methods (TEM, AMT) and reflection/refraction Seismics, were used to provide sufficient depth and spatial resolution. Actually, all methods are capable of identifying sedimentary thickness – such as depth to bedrock – and architecture, although each method has different strengths. We also cored the upper most few meters on both sites to investigate specific sediment composition and subrecent sedimentation rates. The aim of the survey was to reveal the potential of both sites for deep drilling operations in the 3rd phase of the CRC-1211 to shed new light on long term Cenozoic climate development of the Namib desert.

  Copyright: © P. Yogeshwar

Besides India, Jordan and Namibia, you have also been involved in or coordinated field campaigns in Greece, Albania, Ethiopia, Israel, Chile, Sweden and Russia. Is there a region that has grown particularly close to your heart?

India! Again and again I am fascinated by the country, its general vibrancy, beauty and liveliness - best of course without seeing all the dirty sides. But actually, many countries have touched me and left strong impressions in different ways. Ethiopia was my first visit to Africa - I was very moved by nature and also by the kindness of the people who helped us there. In Chile I did some real camping for the first time and it was really great to be in the desert for a longer time - a bit "back to basics". Namibia was just a unique nature experience - a beautiful country and very easy to travel to. I will definitely do another camping trip in nature, and maybe future projects would be great.

  Copyright: © P. Yogeshwar

You have already received two teaching awards at the University of Cologne in 2014 and 2015. What is important to you in teaching and what do you expect from your students?

It is really important for me, to be able to convey geophysical methods in a somewhat understandable and complete way. It does not help much to only dig through theory, without getting a practical feeling for a method and how it is applied. From my experience, often some basic conceptual idea or understanding is missing to be able to put a certain theoretical description into context. So I really try to be active in teaching - where I see gaps or difficulties, I do my best to support and select material for a deeper understanding. On the other side, I surely do appreciate students that share their enthusiasm, engage themselves and participate so that teaching becomes more of an exchange with interaction and room for discussion. Overall, it is important to me that teaching is an enjoyable experience on both sides and there is aliveness in the lecture.


Which courses will you teach during your professorship? Will you also offer excursions?

For this summer-term, I will give courses and exercises for the Masters module „Geophysics – I: Theory of geophysical prospection methods“. The courses shall basically cover the fundamentals of classical geophysical methods from geolelectrics, via electromagentic methods to potential methods and seismic. We will also work on programming and data analysis. In the winter-term, there will be the Bachelor course in fundamentals of Geophysics and the Masters course in Geophysics II, in which we will go a bit deeper into inverse modeling theory. Everything was a bit on short notice, to come up with an extensive excursion plan. However, I do want to offer some daily electromagnetic mapping excursion in the summer-term break, possibly on some archaeological target. Currently, I am also involved in the preparation of large scale semi-airborne EM surveys in Sweden and the Harz Mountains. We always require man-power in the field. In student times, these surveys were always a great opportunity for me to learn and engage myself – so maybe there are some interested students.

Thank you very much for the interview!