CRUSTAL AND UPPER MANTLE STRUCTURE WITHIN THE VICINITY OF THE EASTERN TENNESSEE SEISMIC ZONE

Crustal and upper mantle structure is investigated in the vicinity of the eastern Tennessee seismic zone (ETSZ) using teleseismic transfer function analysis. The ETSZ is 300 km long by 50 km wide, extends from northern Alabama to Virginia, and is roughly parallel to the Appalachian Mountains. Large magnitude, structurally damaging, earthquakes have not occurred within the ETSZ in the instrumental past, however, relatively high annual strain energy release suggests that the potential exists. The ETSZ is also host to the New York-Alabama (NY-AL) magnetic lineament, a large aeromagnetic anomaly interpreted as basement structure. Data come from 10 short-period and three broadband stations maintained by the Center for Earthquake Research and Information (CERI). Station TZTN is maintained by the Incorporated Research Institutions for Seismology (IRIS). Radial component P-wave transfer functions are inverted for velocity structure beneath each individual station in order to assess the crustal and upper mantle structure. Results show dissimilar velocity contrasts on opposing sides of the NY-AL magnetic lineament. Velocities within the upper 10 km and 30-50 km depth range are lower west of the lineament than their counterparts to the east. A gradational Moho boundary is identified at several stations within the Valley and Ridge province. Four stations within the Valley and Ridge province, located east of the NY-AL magnetic lineament, and south of 35.5°N, show an absent Moho boundary.