https://doi.org/10.1190/1.3457445

Did Quantum Physics solve Seismic Inverse theory? – A SEG Honorary Lecture

Short answer: kind of yes. Keep reading anyways.

I passed by the poster of announcements and read “Full-wavefield …” and figured that talk might be outside of the realm of what I understand. Anyone working in FWI has always been clear that it is very complicated. So I never tried.

But this was the Honorary Lecture by SEG and it was Ivan Vasconcelos who was holding it. Heard the name before, so I went. I got lucky in several ways. I was lucky being a “visiting scholar” at ETLP just the right two weeks. Additionally, I was lucky that I got confused with time-zones and showed up an hour early. So I chatted to Ivan for that time. He was extremely nice about a random Phd student rambling to him, kudos to that.

He has some amazing ideas about applying inverse theory in geophysics, medical imaging and astronomy. Having recently left Schlumberger Gould Research in Cambridge he is bringing some applied geophysics to Utrecht University. And as always, when people say they do applied research in geophysics, you sure have to know your physics to understand what they are talking about.

Turns out he knows a lot of people, including my thesis supervisor Dirk Gajewski in Hamburg. Turns out he knows Gabi Melo from Brazil with a Phd from MIT doing amazing work on seismic interference. Turns out he knows Matteo Ravasi, who I met at the Agile* hackathon and seems to do close to everything involving seismic. Turns out the world is tiny and that’s why he pops up in my LinkedIn all the time.

SEG Honorary Lecture

Also turns out I should have read the title in its entirety:

“Full-wavefield focusing in seismic imaging – Concepts, applications, and examples”

This talk is not about FWI. It is about some amazing developments in seismic inverse theory. Go to the talk, you can see all dates and locations here. I will say if your mind is not blown after this talk, you did not fully understand it.

We know seismic inversion is ill-posed. Not only do we not know what it looks like below, we can only measure it from one side. Our equipment is band limited and usually dragged through a noisy acoustic medium. Yet, some smart people went back to a theory from 1963 detailing the “Inverse Problem in the Quantum Theory of Scattering” [1]. They used some smart tricks on this ill-posed problem and came up with an imaging technique that can handle internal multiples.

In the talk Ivan Vasconcelos details everything from the ill-posed problem all the way to their first results from Marchenko imaging, the solution to a problem many did not know they had. Does this sound like a huge cliff-hanger? It is, but I would not want to spoil the fun of attending the talk. Want to read more about this after the series finishes? Let me know in the comments.

Bonus

There is an open source package available for testing.

Bonus 2

I have compiled a helper handout for those a little bit further from university to get through some keywords in the talk. Download.

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... is a geophysicist by heart. He works at the intersection of machine learning and geoscience. He is the founder of The Way of the Geophysicist and a deep learning enthusiast. Writing mostly about computational geoscience and interesting bits and pieces relevant to post-grad life.
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