Note: The Yearbook’s annual membership register
only lists members in good standing, i.e., the annual fee of $20 must have been paid by April 30. Those who have not paid please take immediate action and remit your fee to W. O. Wunderlich, 3221 Essary Dr., Knoxville 37918. If you are not sure about your membership status inquire by email with firstname.lastname@example.org. The Yearbook draft will be completed by December 31, 2009 as I retire from the Secretary/Treasurer position at that time. Walter O. Wunderlich.
Paleoseismicity. On August 31, Dr. Stephen Obermeier, USGS research scientist emeritus from Reston, VA, gave a presentation to the TSK about a project by the Nuclear Regulatory Commission to search for traces of major earthquakes in the East Tennessee Seismic Zone (ETSZ). It is known that there were major earthquakes in the eastern U.S. in historic time, in Charleston and in New Madrid, but no earthquakes beyond M = 4.8 have been recorded in the ETSZ. M = 5.5 is considered the intensity threshold of significant damage causing events, and M > 7 is considered a major earthquake. The ETSZ is the second most active seismic zone in the eastern U.S. behind New Madrid. It stretches from just north of Knoxville into NW Georgia and NE Alabama, about 275 km long and 65 km wide. The USGS rated it as capable of M = 7.5, which is considered a major earthquake (eq) causing regional damage.
Prof. Robert Hatcher is leader of a task force to find evidence if eq’s M > 5.5 have occurred in the ETSZ during the past 10,000 to 20,000 years, and if so, to begin the process of estimating their maximum magnitude and recurrence. What Prof Hatcher and his collaborators are looking for is evidence of earthquake-related liquefaction features in river terrace sands, stream banks and along reservoir shore lines including faulting. It didn’t take long for them to find what seem to be possible liquefaction fractures in terrace deposits along the French Broad River near Dandridge. Vigorous compression and shaking seems to have squeezed mud and sherds of underlying shale upward into the fractures in
the Pleistocene to Holocene alluvial deposits. In addition they found a displacement of about 19
cm of such a fracture by a fault, which means that the entire terrain has undergone some lateral movement, requiring a significant eq. There are five river terraces along the meanders of Douglas Lake. The emplacement of fractures in these terraces gives a hint of how long seismic activity has been going on. The top terrace T1, the oldest, is outside the present lake, whereas the youngest (T5) is next to the present river channel. A suite of fractures in the T2 (~28 000 years) terrace has been identified. Also crossings of older by younger fractures have been found indicating a continuing seismicity over time. These are preliminary findings and interpretations that will need further examination (From a progress report on PALEOSEISMIC INVESTIGATION OF THE EAST TENNESSEE SEISMIC ZONE: PRELIMINARY RESULTS by Stephen Obermeier; James D. Vaughn; Robert D. Hatcher, Jr.; Hugh H. Mills; S. Christopher Whisner, and Christopher W. Howard; contact: email@example.com). WOW.