Feb 27- Mar 3
Background history for the DISC in India
India has 1.2 billion people, a plethora of universities, and a young population that is technological and wanting to advance. To reach the audience and make an impact, we initially planned to have 3 presentations. (Hyderabad, Bangalore, Mumbi). To arrange a trip in India, we contacted NGRI (National Geophysical Research Institute) which is the leading geophysical research institution in India. Virendra Tiwari is the director, Ajay Manglik is the Chief Geoscientist, and Vijay Dimri is the ex-director. After a Skype conversation, the NGRI group formulated a plan in which we would present the DISC only at Hyderabad and they would bring in geoscientists from various locations in India. To make it even more worthwhile for attendees they also planned to organize a two-day EM workshop that would follow the DISC. That would provide ample opportunity for us to get connected with geoscientists and their problems throughout India and for Indian scientists working on EM problems to get reconnected. India had not had a national EM conference/workshop since 2002. It was an ideal opportunity for everyone.
The organization of this combined event was superb. NGRI advertised the DISC and screened applicants to make sure they would benefit; the number of attendees was capped at 100 to ensure the event would
have a “workshop” flavor rather than a conference. The number of applicants exceeded 100, so in the selection process, they tried to ensure that the major universities, societies and companies were represented. The participants, from universities, industry and government agencies, came from all sections of India (see map below). Some took a 2–5 hour flight while others, particularly students, travelled 30+ hours by train.
Although Hyderabad doesn’t seem that far from Bandung on the map, it was a long flight!. We arrived at the airport around midnight and, thanks to Babu’s kind escort, we safely arrived at our guest house at NGRI. It is an oasis located in the center of Hyderabad and its 16000 trees deaden the noise of chaos in the surrounding area.
After a good sleep, we met the organizer of the DISC event and EM workshop, Ajay Manglik. He explained how carefully they had organized the event and discussed the vision that he had for elevating the EM community in India. We found that we had a special connection with Ajay. His master’s thesis on magnetotelluric (MT) inversion had lots of connections with one of Doug’s old papers on the subject.
Ajay and Doug. Ajay’s MSc thesis was entitled “Backus Gilbert Magnetotelluric Inversion”
In India, a conference begins with a lamp lighting ceremony. “The light brings brightness; in doing so, it dispels darkness and we begin to see things clearly.” That seemed to be a perfect metaphor for our goals for the day.
About a 100 people from universities, particularly the numerous branches of IIT (Indian Institute of Technology), government organizations (CSIR-NGRI, GSI (Geological Survey of India), IIG (Indian Institute of Geomagnetism), AMD (Atomic Minerals Division), ISR (Institute of Seismological Research)) , and companies ONGC (Oil and Natural Gas Corporation Limited), attended the event. About half of the participants were graduate students.
Technical abilities were mixed. Some attendees were very knowledgeable in some aspects of EM, their application, and understood the computational details of inversion. Many of the remainder had collected EM data (mostly MT) and had inverted the data with available software and carried out an interpretation. They were practitioners. The remainder of the audience had only a moderate familiarity with EM fundamentals or applications. The primary application areas were:
- Geological structure of India: For understanding geologic hazards (earthquakes and landslides) particularly in the Himalayan region where the Indian and Asian plates are crunching together.
- Minerals (India hasn’t had a significant discovery in the last 20 years): All minerals are of interest but particularly uranium (AMD: atomic minerals division).
- Water issues: Where is the water? Pollution problems. Sustainability.
The main EM techniques currently used for these applications are:
- MT (India has thousands of soundings)
- DCR (for slope stability) and also for groundwater (but often only very sparse VES soundings)
- Recent airborne TDEM: (VTEM and SkyTEM)
The topics of DCR, inductive and grounded sources, and natural sources were thus of great interest and attendees were engaged and attentive throughout the course. The apps were a hit and were used to review fundamentals, but there was not sufficient time to allow participants to play with them; that would have to wait for DISC Lab day. The case histories we chose resonated with attendees. In particular, a hydrogeological case history, Kasted, got significant attention due to its integrated interpretation, and potential application for ground water problems in India. Airborne EM data were inverted to obtain the conductivity structure of the Kasted region, and finally, a hydrological model of the region was built for the fluid simulation.
Feed back quotes:
It is nice to review fundamentals, especially to see that overall, things are built in an open source platform. Definitely it is motivating and broadening horizons.
It was a wonderful day for me. As I am new to EM geophysics, today was the opportunity for me to learn about EM Geophysics.
I’ve been introduced to some new EM techniques and learned so many things in a whole new way. It was pretty good experience. It was fortunate for me to attend the fantastic lecture by Professor Oldenburg.
The day did not end until 7:30pm, but the audience was continually engaged. We entertained more questions at this venue than at any previous location. There was exceptionally great interest in how the forward simulation and inversion were carried out. This prompted us to change the format of DISC Lab day to concentrate upon showing how the apps were generated and to provide a tutorial on the use of SimPEG for numerical computations.
The DISC Lab was held in the NGRI electronic room, which has internet and lots of power outlets for laptops. Rather than trying to capture problems that people are working on, we decided to focus on computation. The room is configured for 50 people but we had 70! It was heartening to see such a good turnout.
Seogi introduced the Jupyter apps (DC and Time domain EM) and led the group through the numerical simulation of the 1D MT problem using SimPEG. This is a perfect tutorial example. Not only does it have foundational pieces for solving more complicated partial differential equations but it is also of practical use.
At the end of DISC Lab we had a wrap-up and discussed how to keep the momentum of the two days going and to get feedback about the material that we presented.
We had a few learning experiences. Our initial plan was to have attendees run the apps on their computers by using Azure. Despite the seeming simplicity of this, the internet bandwidth and the variety of laptops with individual issues, conspired to make this less effective than we had anticipated. After the morning coffee we changed into a tutorial mode with questions. We also had hoped to have time to discuss important aspects about the inverse problem but that did not happen. They still appreciated what we did and what we were attempting to accomplish.
The two-day workshop was kicked off by our Keynote talk “All Charged Up: Advances and applications for Induced polarization (IP) surveys”. The titles of presentations and authors are listed on this link. Some specific insights and outcomes from the workshop are listed below:
- MT is the most widely used EM technique in India. Thousands of data sites have been collected with the goal of understanding tectonics and earthquake risk. MT has been, and continues to be, used to delineate sediment thickness below the basalt with the potential application to hydrocarbon exploration.
- Although MT data were being inverted in 3D by using open source software (primarily Weerachai’s code) knowledge about how responses were simulated by the code, and important details about the inverse problem, were found to be scarce.
- Airborne EM, particularly TEM, is becoming popular. India owns a VTEM system and it has recently had 6 SkyTEM pilot surveys carried out. Delineating the near surface structure is important for mineral exploration, water, and geotechnical problems. Capabilities seemed to exist to simulate data numerically in 1D but not in higher dimensions.
- Our EM case history that used LoTEM to delineate sediment thickness in Saurashtra peninsula was topical. Interacting with Prasanta Patro we discovered that the area also had extensive (600 stations) of MT over it (seismic, gravity and other surveys). This opens the door for further analysis and an interaction.
- Signal processing problems (particularly going from recorded time series to MT impedances) were of significant interest to many groups but the details about how the MT impedance obtained from the time series was accomplished were not apparent, and even though open source exists for this analysis, it is difficult for individuals to modify.
The workshop ended with a group discussion about how to capitalize on the momentum generated by the DISC and the workshop. The Indian panel members focussed upon mapping out a vision for the future. These included: having a nationwide EM workshop every couple of years, having more events like the DISC Lab, but extended for a week, that focussed on computational techniques relevant to simulation and inversion, and developing a closer interaction between Indian groups that are acquiring/interpreting EM data (particularly MT and airborne EM) for various applications.
To keep communication lines open between the DISC team and the participants in India, we will be communicating through the GeoSci channels: Slack (http://geoscixyz.slack.com) as well as the GeoSci resources (http://geosci.xyz). The immediate focus is development of three themes:
- MT Processing: development of open-source software to extract MT impedance and tipper data from time-domain signals
- Simulation and inversion: development and deployment of tutorials for simulating EM responses and carrying out inversion
- Working with NGRI to invert MT and LoTEM data in the region of Saurashtra peninsula to recover sediment thickness below the basalt. The results from the specific area in India are interesting in themselves but the procedures implemented will have applicability elsewhere in India.
We hope that by focussing conversations on a select set of problems of interest to DISC 2017 participants in India, the GeoSci-India participants can be leaders in the fostering of local communities and rallying around the development of resources to elevate the use of geophysics in India.
Our trip to India was highly successful and we hope we have been a positive catalyst for the development of EM. Any success we have is attributed to the organizing group at NGRI. We particularly thank Ajay Manglik, Virendra Tiwari, Vijay Dimri, and Saurabh Verma. In particular, Ajay’s boundless energy and attention to detail allowed the events to be carried out seamlessly and with ample opportunity for all participants to interact. Lastly, we don’t know who was responsible for catering the lunches but they were amazing!
Appendix: Posters from the EM workshop
EM imaging of Saurashtra region / Kumar and Singh
Geo Electromagnetic studies in North Indian Ocean Region / Anusha Edara
Study of Lithospheric structure across Cambay rift basin using magnetotelluric study / Krishnan et al.
Geologic separation using fuzzy constrained resistivity tomography / Anand Singh
Near surface imaging of the waged active fault systemby TEM studies / Negar et al.
VLF anomalies associated with gold mineralization near Lawa village / Akanksha Upadhyay