Dr. Will Pettitt, Principal Geophysicist at Itasca Consulting Group, has reviewed the seismic data recorded overnight on November 20/21. Long-period seismic tremors and micro-earthquakes have been observed, similar to those defined previously by Dr. Steve Horton of CERI/USGS, and recorded mainly on station LA08 closest to the sinkhole. The long-period seismic tremors are postulated to be caused by gas and/or fluid movements through the rock collapse zone below the sinkhole on the edge of the salt dome. . . .