Group , Poster #064, Earthquake Geology

Near-field deformation of the southeastern strand of the 2019 Ridgecrest mainshock

Mercedes Quintana, Alba M. Rodriguez Padilla, Duncan M. Chadly, & Michael E. Oskin
Poster Image: 

Poster Presentation

2021 SCEC Annual Meeting, Poster #064, SCEC Contribution #11354 VIEW PDF
The Ridgecrest earthquake sequence occurred in July 2019 in the Eastern California Shear Zone, generating a complex surface rupture. Some sections of the surface rupture were captured with 2-20cm per pixel drone imagery collected by Pierce et al. (2020). Using this imagery, we mapped the southeastern strand of the mainshock surface rupture. This map unveils the near-field deformation of that section with unprecedented detail, showing secondary fracturing below the resolution of airborne lidar data and other geodetic methods. The rupture is fairly localized through this region, with the exception of a large break where it forms a broad zone of deformation tens of meters wide, perhaps indicating a change in sediment cover thickness or incomplete rupture through a velocity-weakening material. Overall, the main rupture trace is linear, organized into small en-echelon segments, without abrupt changes in fracture orientation. The rupture becomes multi-stranded at the southern terminus of this section, as it approaches the rupture tip. These high-resolution images highlight the complexity of this earthquake sequence and will guide how future earthquake surface ruptures are assessed.