Analysis from Itasca Group on recent seismic monitoring that can be posted to Assumption blog to give information to public on latest evaluation —
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. Micro-earthquakes of this nature are typically associated with small-scale rock movements, and again are believed to be occurring in the collapse zone. The source of both of these event types continues to be investigated by experts.