Assistant professor Kiser provided information regarding another incident that occurred on Nov. 28, 2017 saying, “I looked through the Tucson station seismic data this morning, and there definitely is an event that shows up around 8:11-8:12 p.m. (See picture below). The seismology group looked at the waveforms today, but it is difficult to determine what the source is, using one seismic station. Generally, we would expect a sonic boom to not be as impulsive as this signal. A mine blast could be the source, but I would be surprised if they were blasting that late.”