Because of their fragility, PBRs act as reverse seismometers; they tell us which earthquakes haven't happened. I map out the locations of these PBRs all over Utah, especially near the Wasatch fault zone, and I make 3D models of them with my students. We then shake these models in a computer earthquake simulation to measure the force required to knock the PBR over. Because the PBR is still there, we know this earthquake has never happened; this provides a limit on the largest earthquakes that could've happened in the past and what their shaking patterns might look like.
If you want to help, simply take a picture of any Utah (or anywhere, really) PBR you happen to find while out hiking/rafting/climbing/etc. and email it to me! Just send me:
Latitude & Longitude
A short description of where you found the PBR
Make up a cool name for the rock!
You can reach me at: firstname.lastname@example.org
Thanks for your help!