I don't think so. I have never heard of any past land fills in the area, but I guess anything is possible. I think there is just a number of earthquake faults in the area, not uncommon to the rest of the state. The state of Nevada is the third most seismically active state in the Union. It becomes pretty apparent when you look at the state from above and see all the mountains and valleys. Looking from east to west across the state you see one range of mountains after another many reaching upward to 10,000 feet. These ranges are created by lifting of continental plates which cause earthquakes. If you look at a fault map there are thousands of faults in this state. You might get more and better info from the USGS.