Many seismic hazard source parameters such as slip rate, total displacement, strain accommodation, geographic fault location, etc. are poorly constrained in the New Madrid seismic zone (NMSZ). This is in large part due to the masking effect of the thick Mississippi embayment sediment package on seismogenic structures and features. Consequently, much of the subsurface geologic characterization needed for understanding seismic hazard sources requires geophysical imaging. Recent seismic reflection surveys 12 km NE of the Reelfoot Fault stepover arm of the NMSZ have suggested a northeast-oriented transpressional fault zone extending across the Reelfoot Fault stepover arm where its dextral displacement at seismogenic depth is unbalanced with the surface expression, the Reelfoot Scarp. New high-resolution seismic reflection surveys were acquired across the southwestern back projection of the hypothesized structure at a potential piercing point with the Reelfoot Fault near Proctor City, TN. The resultant images show steeply dipping northeast striking faults with uplifted and arched post-Paleozoic reflectors that extend into the Quaternary sediments, consistent with the findings of the previous surveys. The new imaged faults form a ~500-meter-wide positive flower structure, with vertical displacements of 16 m and 50 m at the top of the Eocene and top of the Paleozoic reflectors, respectively. Results corroborate the Axial Fault extending to the northeast, and provide geological evidence for Reelfoot Fault segmentation. Furthermore, the near-surface SH-wave seismic profiles show the through-going shear deformation has continued into the Quaternary, thus indicating seismogenic strain has not been completely transferred to the Reelfoot Fault, providing additional evidence for accommodating the strain imbalance.
| Identifer | oai:union.ndltd.org:uky.edu/oai:uknowledge.uky.edu:ees_etds-1086 |
| Date | 01 January 2019 |
| Creators | Rosandich, Brooks |
| Publisher | UKnowledge |
| Source Sets | University of Kentucky |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations--Earth and Environmental Sciences |
Page generated in 0.0015 seconds