Poster

Описание: 2020 SCEC Annual Meeting 1min Lightning Talk

Authors: Lauren A. Ward, Bridget R. Smith-Konter, Xiaohua Xu and David T. Sandwell

Abstract: Benefiting from both spatially and temporally dense instrumentation and remotely sensed observations, deformation from the 2019 Ridgecrest earthquake sequence is poised to become one of the best observed co- and postseismic processes to date. These new observations add to an already rich record of crustal motions provided by three other greater than Mw7 earthquakes in southern California over the last 3 decades. In particular, vertical time series data from Ridgecrest are beginning to reveal transient postseismic motions that are strongly influenced by lithosphere rheology. Here we focus on the vertical earthquake cycle deformation signal and its sensitivity to spatial variations in lithosphere rheology by leveraging new crustal deformation data acquired from the 2019 Ridgecrest earthquake sequence. We utilize a 4-D semi-analytic viscoelastic deformation model that simulates both the elastic and time-dependent viscoelastic response of body force dislocations embedded in an elastic plate overlying a viscoelastic half-space. The model is additionally able to simulate lateral variations in crustal rheology parameters, which we define using the SCEC CTM. We find that postseismic vertical velocities ~1 year after the Ridgecrest earthquake are largely in response to a 3e17 Pa•s asthenosphere viscosity underlying an elastic plate thickness ranging from 45-60 km in the central Mojave region, bounded by a much thicker nearby Sierra Nevada plate to the west. Moreover, a key observation of the far-field Ridgecrest postseismic vertical velocity field is that postseismic vertical deformation is predominantly in the direction opposite of deformation prior to the earthquake. This intriguing and well-imaged vertical signal, which will continue to evolve over the next several years, provides a unique opportunity to better understand the role of elastic thickness variations and transient viscosities at play in the Eastern California Shear Zone.