I’m Rachel Hopkin – the host and producer of How Curious – and this How Curious episode explores a momentous scientific breakthrough which took place in Oklahoma in the early 20s and continues to have worldwide consequences today. It was Oklahoma geophysicist Jan Dodson who suggested this subject. Jan emailed me back in February to let me know about an event that would shortly mark an extremely important but little-known part of our state’s history – how Oklahoma became the birthplace of reflection seismology.
The event was called the Seismic Reflection Centennial. It took place over three days in April and included a range of presentations plus a one-day field trip. It had originally been planned for April 2021, but Covid pushed the meeting by two years. The participants consisted largely of geophysicists and geologists at various stages of their careers, including many students. I’ll be the first to admit that I’m not great on science, but Jan’s brief missive made it clear that the seismic reflection research and experiments carried out here in 1921 had been momentous.
So what is reflection seismology? It is a methodology that uses ground vibrations to explore what lies beneath the earth’s crust. Since its invention in Oklahoma, it has generated untold economic wealth through its ability to locate sub-surface natural resources such as oil and gas. In addition, its principles have been deployed for many other important purposes. As we set off on the field trip, I asked Jan Dodson to outline the circumstances which precipitated this world-changing innovation.
"Oklahoma has been a huge producer of oil and natural gas historically. The Native Americans found oil and gas seeps around the Arbuckle and Wichita Mountains. At the time, they weren’t using it for gasoline, but they used it for medicine and all kinds of things like that. And then the internal combustion engine was developed and there was a demand for gasoline which is a refined product from oil and gas and so because there were seeps in Oklahoma, people began drilling."
The early methods used to locate these resources were pretty rudimentary.
"They started drilling on what we call a “surface high” – a little high spot on the surface of the earth. It’s probably not even a hill, it’s maybe just 10 feet. When rocks are originally deposited, there is organic matter buried with them. And as more rocks accumulate on top, it gets compressed and hot. And so chemical changes happen and the organic matter that’s contained in those rocks begins to convert into oil and gas, into hydrocarbons. Hydrocarbons are lighter than the rocks and they begin percolating upwards molecule by molecule."
Think of cream rising to the top of milk. But it’s easy to use a spoon to scoop the cream off the top, whereas oil and gas are usually hidden below the earth’s surface. In order to find significant stores of them, you need to find places where reservoirs have formed in traps between two different layers of rock. These rock traps tend to follow certain formations, including the shape of a dome. And, Jan said, if the geology is a certain type of geology, that dome will be expressed slightly at the surface of the earth. So surveyors went out with their very basic survey equipment a hundred years ago and surveyed what we call a topographic high and they drilled there and sometimes they found oil and sometimes they didn’t."
Since those topographic highs could be caused by host of other activity - including erosion - the success rate was pretty hit and miss. But as the 20th century brought with it an ever-increasing demand for hydrocarbons, researchers all around the world were working to find more reliable methods to access them, among them a young man named John Clarence Karcher. Karcher was born in Indiana in 1894. The family moved to Oklahoma when he was a child. He studied physics and electrical engineering at the University of Oklahoma and was working on his Ph.D. in Pennsylvania when the United States Bureau of Standards recruited him to help the military. As Jan explained: "During WWI, scientists were locating artillery shells and bombs by triangulation. They knew that that energy was traveling through the earth, and they were recording it at some distant location. And if you have three points around that explosion, you can locate where that explosion is."
Karcher was one of the people involved in this effort and he learned a great deal in the process. Once the war was over and he’d completed his doctorate, he returned to work at the University of Oklahoma where he already had many supportive colleagues, including expert geologists who knew about what lies beneath the earth’s crust. It was an exciting time. Karcher believed that just as acoustic waves – which move through the air - helped pinpoint war activity, seismic waves – which move through the earth - could be used to locate sub-surface matter. Jan said, "Karcher knew that people were looking for oil and gas, and he was a young guy. Young kids sometimes have fabulous ideas, and he got this idea that you could use an energy source like an explosion and record the echoes at a surface location and map the subsurface of the earth."
With colleagues from OU, Karcher’s first experiment took place on June 4th, 1921. A monument marking the event stands behind OKC’s Belle Isle Library building. This was the first stop of our field trip.
Jan talked about the location of the monument:
"As far as I can tell, this area was a farm. John Clarence Karcher knew the owner of the farm. His notes say the first location was a mile and a half west of the Belle Isle amusement park, so that’s as close to the location as we know. The monument was placed here in 1971 when they celebrated the 50th anniversary. You can tell that they have lots of rock samples around the base of the monument and all of those samples represent oil and gas-producing formations in the area."
The field trip was led by structural geologist, Molly Turko. After attendees had had time to admire the monument, Molly referred to the field trip’s accompanying guide which included talking points for each stop on the tour. One for this stop related to how seismic data is acquired. A knowledgeable attendee responded as follows: “There’s a source. The waves go down. They hit a contrast in acoustic impedance which is velocity and density. They come back and are recorded somewhere else at a receiver and then the processing is all the geometric corrections."
This stuff was probably very basic for most people present, but it was new to me, so as we continued on the field trip, I asked Jan to tell me more. For example, what Karcher had used for the source – i.e. how was the initial sound being produced? And how was the information it sent captured?
"They used a dynamite charge, and they had some kind of microphone that was attached into the ground with a spike so it could feel the ground motion. The microphones had a mirror attached and they had a light beaming on the mirror. And the mirror reflected the light onto photographic film that was advancing at a certain rate, so the light would expose the photographic film in the form of wiggles as that microphone wiggled up and down. To my mind, this was an ingenious contraption to record this."
No kidding. My head was spinning. The Belle Isle experiment was promising. From the photographic films, it was clear that the method was indicating different layers of substance in the earth. This is because the rate at which sound travels through matter varies according to the type of matter. But since the Karcher team didn’t know exactly what rock layers were beneath Belle Isle, nor how thick they were, they had to organize a new experiment.
For this, Karcher needed to find a location with a variety of subsurface rocks in uneven formations and which had already been measured and documented. He decided to look for a site within the Arbuckle Mountains, where he knew that there were many irregular rock layers which geologists had carefully mapped out. In fact, there are lots of places where drastically distorted rock layers are visible at surface level via outcrops. We looked at a number of them during the field trip.
Then the final stop of the day took us very close to where that second and all-important seismic reflection had taken place. Molly Turko set up the scene: “We found the location through his publications. He said it was ‘along Vine’s Branch Creek which flowed along the base of an eastward plunging dome, capped by the Viola. Beds dipped to the east’."
Molly pointed towards the direction of where the experiment occurred, though it was hidden from view by a ridge. Karcher chose an area beneath which geologists had already mapped out where and how the layers of Sylvan Shale, and Viola Limestone were formed, their changing thickness, and where they actually met. Though both rock layers dipped at angles, they did so at different rates. When the results of second experiment turned out to match up precisely with pre-existing maps and measurements of the area, Karcher knew that his idea had worked. It was a scientific triumph. Jan Dodson affirmed this: “By proving that this concept works, he was then able to map subsurface structures that were not evident from the surface of the earth. It’s literally a way to map the subsurface of the earth."
Ironically, Karcher’s breakthrough took place at a time when oil prices were low so it took a few years before his work began to reap economic benefits. 1928 was the year that the first productive oil wells drilled using reflection seismology. Countless others followed. Karcher became a successful businessman as well as scientist and died in 1978. Meanwhile, the seismic reflection methodology he invented has evolved exponentially. It still provides the basic means of locating oil and gas and has also developed in many other directions. This was evident in some of the research that was presented in poster format back at the OKC meeting.
One of the people I met in the poster room was Silas Adeolawa Samuel. He is a PhD student at Oklahoma State. His poster explained how his research is blending reflection seismology with environmental conservation. As he explained: “We need to find ways to try to reduce the effects of climate change so one of the ways my research is trying to fix that is by finding storage sites in the underground or in rocks where can store captured CO2 from the atmosphere."
Bobby Buist is studying for his PhD at OU. His poster described his research which is using seismic data to explore the ancient history of a buried valley in the southwestern part of Oklahoma valley. He said that it’s “generally agreed that there’s glaciers and glaciation at the pole of the earth. However, if this valley – which is at a higher elevation – was made by a glacier, that’s sort of counterintuitive to what people know as of right now. So if it’s made by a glacier, it reshapes our understanding of earth’s history."
In other words, the work conducted by Karcher and his team in Oklahoma back in 1921 remains extraordinarily relevant today. Jan Dodson summarized this for me:
"It’s used in environmental work. They using related technology for archaeological work - Native American burial grounds. They’re using it in Tulsa, OK, to find mass graves from the race massacre up there. Ultrasounds, which we routinely use for medical tests - that is the exact same technology that Karcher developed. But it’s on millimeters instead of miles. It has wide, wide, widespread use to all kinds of modern life."
I’m so grateful to geophysicist Jan Dodson for bringing such an important Oklahoma story to the attention of How Curious. Special thanks to Professors James Knapp and Brett Carpenter, as well as to the many other participants of the Seismic Reflection Centennial. Thanks also to Daniel Tureck and Nyk Wynes.
How Curious is a production of KGOU Public Radio. It’s produced and hosted by Rachel Hopkin. The editor is Logan Layden and David Graey composed the theme music.
If you have an Oklahoma-related question or subject that you’d like How Curious to cover, please email us at curious@kgou.org.
