• Ryan Pollyea

Old Dog, New Tricks

Updated: Jun 27

I've been employed as a geoscientist for over 20 years, which feels strange because the academic community considered me an "early career" scientist until last week. It's an unfortunate fact that academics put little value on professional experience outside of "The Academy." Nevertheless, my geo-career spans a range of environmental and geotechnical consulting, goverment oversight, and now academics. I've characterized contaminated groundwater sites, managed drill rig operations, modeled all types of geologic fluid systems, taught hydrogeology, and more. This work has been fulfilling and sometimes it's quite fun! But after 20 years...twenty's time for this old dog to learn some new tricks.

It all started about two years ago, when a USGS colleague asked me to speak with a managed aquifer recharge (MAR) operator in southeast Virginia about injection-induced earthquakes. After discussing the history and science of injection-induced seismicity with this group, I was given a small grant to model fluid pressure propagation from a hypothetical large-scale MAR project in the Virginia Coastal Plain. As this project developed, a Virginia Tech colleague told me about a set of microseismic monitoring instruments that was both underutilized and freely available for research, if someone were willing to house the instruments and care for their batteries. Now, one thing to know about me is that I am always looking for opportunities, and when someone says they have 600 5Hz 1C geophones, 200 3-channel seismic data recorders, 400 external battery packs, peripherals, software, etc., and that all this equipment just needs a loving home, well, that gets my attention. So, by this point, I've had a run of successful papers about injection-induced earthquakes, I have a decade of experience managing field operations, I have access to a fully functional, professional-grade microseismic monitoring rig, and I am collaborating with an MAR operator right here in Virginia. All good, right? Except...I'm a hydrogeologist, not a seismologist.

Sercel Unite data recorders in front of Derring Hall.

So, motivated by what feels like a tremendous opportunity in a research field (induced seismicity) that I think is really important, I decided to begin learning seismology. In January, I took a Sercel training course with my colleague, Dr. Martin Chapman (who is a seismologist), to become certified in seismic data acquisition using the Sercel Unite cable-free system. And then I took Martin's graduate-level (spring 2021) course in strong-motion seismology to learn theory. With these preliminary steps complete, Martin and I are now collaborating on a bit of software development to convert the SEGD files produced by the Sercel data recorders into a format that we can analyze using Seismic Analysis Code. The learning curve is intense, particularly the seismic data standards, which often feel not-so-standard. Nevertheless, I've been able to setup the instruments, run them continuously, export the data, write the data to SAC format, filter the data, and write out seismograms. In fact, the seismogram below is from a M6.7 earthquake on the South Pacific Rise that I recorded in my backyard - my kids think it's really cool that we "had an earthquake in our backyard."

M6.7 EQ in S. Pacific as recorded in my backyard.

As the summer progresses, Martin, Ethan Conley (incoming PhD student), and I are gearing up for a microseismic monitoring campaign at a pilot-phase MAR site here in Virginia. This is a fascinating site, and one that I hope to write about more frequently in future posts. In the meantime, there is much to learn about seismology, but I do hope that combining my background in geologic fluid systems with seismology theory and seismic data acquisition will unlock exciting new research directions for the Computational Geofluids Lab. Wish us luck & feel free to contact me if you're interested to know more.

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