Group B, Poster #108, Earthquake Geology
Evidence for late Holocene multi-fault rupture in the Panamint Valley transtensional relay, Eastern California Shear Zone (ECSZ)
Poster Image:
Poster Presentation
2022 SCEC Annual Meeting, Poster #108, SCEC Contribution #12484 VIEW PDF
zone using National Center for Airborne Laser Mapping (NCALM) lidar DEMs, aerial imagery, and developed a fan chronology consisting of ten generations of late Pleistocene to Holocene alluvial deposits, based on changes in bar and swale morphology, weathering, and desert pavement development. We further date offset deposits using post-infrared feldspar infrared-stimulated luminescence and quantify rupture kinematics offsets at over 250 piercing points in alluvial surfaces using newly generated high resolution (5 cm) drone-based structure from motion digital surface models.
Our high resolution fan mapping and geochronologic dating show three key results: 1) faulting in the transtensional relay is distributed over 100+ fault strands located between the Ash Hill and Panamint Valley faults, occurring in parallel and en echelon arrays, 5-7 km in length, with fault spacings up to 100s of meters; 2) the relay zone has accommodated four earthquakes over the past ~4 ka, and the timing of these events overlap with ruptures on the adjacent Ash Hill and Panamint Valley faults; 3) displacement magnitude per event ranges from 0.6 – 1.0 m of right lateral slip and 0 – 0.2 m of dip slip, with slip kinematics similar to that of the Ash Hill fault. These results suggest that strain is transferred between the Ash Hill and Panamint faults over multiple earthquake cycles via the complex faulting in the transtensional relay, and that strain transfer may be accommodated by slip along an inherited low angle normal fault underlying Panamint Valley. Moreover, our methods and analyses demonstrate how paleorupture extent in fault transition zones may be characterized to determine where multi-fault ruptures may impact seismic hazard estimates.
SHOW MORE
Our high resolution fan mapping and geochronologic dating show three key results: 1) faulting in the transtensional relay is distributed over 100+ fault strands located between the Ash Hill and Panamint Valley faults, occurring in parallel and en echelon arrays, 5-7 km in length, with fault spacings up to 100s of meters; 2) the relay zone has accommodated four earthquakes over the past ~4 ka, and the timing of these events overlap with ruptures on the adjacent Ash Hill and Panamint Valley faults; 3) displacement magnitude per event ranges from 0.6 – 1.0 m of right lateral slip and 0 – 0.2 m of dip slip, with slip kinematics similar to that of the Ash Hill fault. These results suggest that strain is transferred between the Ash Hill and Panamint faults over multiple earthquake cycles via the complex faulting in the transtensional relay, and that strain transfer may be accommodated by slip along an inherited low angle normal fault underlying Panamint Valley. Moreover, our methods and analyses demonstrate how paleorupture extent in fault transition zones may be characterized to determine where multi-fault ruptures may impact seismic hazard estimates.
SHOW MORE