Near Surface Geophysics, Vol 26.1

Near Surface Geophysics

The Learning Curve for Shallow Reflection Surveys

In the 1980’s, Near Surface Geophysicists were just learning to do shallow reflection surveys. Foundational papers were coming out of the Geological Survey of Canada, the Kansas Geological Survey, and the University of Utrecht, among others.

In that time frame, there were just a handful of geophysicists doing shallow reflections in the Western World and they were in no way routine. As discussed in my earlier article[1], there was a serendipitous confluence of seismic instrument developments and geophysical methods that made shallow reflections doable and we just needed to spread the news to the practitioners.

We sold a lot of instruments into China in the 80’s, and Geometrics was exhibiting at a trade show in Beijing.  One of our customers came into the booth with a seismic record to show me some beautiful reflection data.  He asked if that was how they did it in the U.S.  I complimented him of course, and told him how few geophysicists were doing this kind of acquisitions.  Enough other geophysicists came by the booth to convince me that half the practitioners in the world were in China.

On another day, another of my customers came by to complain that the equipment he had purchased didn’t get shallow reflections. I told him that he wasn’t doing it right, which led to one of those “o yeah” conversations, and he challenged me to show him.  He arranged to bring a bus, his crew and his system back the next day, and took me out to the field site.  My recollection (it’s been a while) is that I managed to get some decent data for his crew and showed him how to adjust the acquisition and display parameters to make it work.  The key of course then was to use some extreme low-cut filters and get the trace display right.

Which brings me to today’s topic.  In the early 1990’s, Rob Huggins signed up Geometrics to teach a course on shallow reflection surveys at SAGEEP (I don’t have the exact year). Something came up and he couldn’t do the course, and I got drafted.  Cleaning my office recently, I stumbled across the binder notes I made for that talk. “They weren’t too bad”, I said to myself. My recollection is dim as to the reception, but I distinctly recall Sue Pullan saying these were great slides. In all humility, and exploiting FastTIMES’ new format with the ability to include links, here they are. This was way before PowerPoint, so the format is made to fit an overhead projector. Someone introducing a student to shallow reflections could do worse than extracting some of these slides. Feel free. They are pretty much self-explanatory, but drop me a note if you have any questions.

[1] Reflections on Shallow Reflections, Fast Times, Volume 24 No. 3, 2019