Student Spotlight: Ben Godwin
How did you choose your topic and what is the main objective of your thesis?
I got an opportunity as an undergraduate to perform research under the guidance of Greg Carling and Steve Nelson. Steve has worked on Pah Tempe for 12 or more years, and had another idea regarding the site that could act as a graduate thesis. After applying for graduate school, I was admitted and began working on Pah Tempe with Steve's guidance. The area is a nice combination of geophysical and hydrogeological features, my two favorite areas of geology. Pah Tempe has been studied and papers published regarding its unique setting in the past, but no one had yet performed seismic surveys to image the subsurface in an attempt to connect spring water inflows with the fault damage zone. That's where my thesis came in. The area is right by the Hurricane Fault, in fact it sits within the damage zone. Fractures are apparent all along the southern canyon wall, so it was intuitive that this damage was fracturing the subsurface rock and acting as conduits for spring water inflow to surface. We wanted to see if this is actually what is happening, and to do so we needed to perform seismic profiles on the canyon roads to view the subsurface, locate major fractures in the canyon rocks and then look for any correlation between them and the spring inflow locations. We found good correlation between most inflows and fractures and subsurface offsets. Thus we have shown that the fractures and faults in the damage zone, created by the Hurricane Fault, are indeed most likely acting as conduits for spring water inflow.
What challenges did you have to overcome?
One of the challenges we faced was the noise from the river and from a water pipe under one of the roads we performed seismic survey on. The river is noisy due to running water, and there was buried a large pipe that brings water from upstream down the canyon to avoid the salt load brought in by the springs. These two sources of running water were seismically noisy, and our resolution of the subsurface was effected by it. Nevertheless, to help get around the noise we increased our stacks (the number of times we put energy into the ground and recorded the returning reflections) to cancel out as much of this random noise as we could, and it worked well.
What is the contribution of your research to the geology community?
Pah Tempe is a site of interest for the state and the neighboring states as the salt load it puts into the otherwise fresh Virgin River water makes the water unusable down stream. There have been proposals by state and federal programs to look at Pah Tempe as a site for desalination. One method to desalinate is to locate a major inflow at depth and to drill down and divert or treat the water using the major flow conduit before it disperses and moves into more fractures. My project can help as it has located a few major offsets that correlate with inflow locations. However, it also shows that the area is so fractured that the springs are coming in from all over the damage zone, and a likely candidate for a single major subsurface treatment isn't practical.