Map showing the locations of individual sedimentary basins in the southern California region (primarily the Los Angeles Metropolitan area), along with ground motion recording stations locations categorized by geomorphic province (basin, mountain/hill, valleys, basin edge).
Schematic of basin response showing resonance and surface wave generation.
Sedimentary Basins are depressions in the earths surface filled with alluvial deposits and sedimentary rocks that are geologically younger, have slower seismic wave velocities than the underlying basement rock, and also decrease in thickness towards their margins.
These basin structures often trap and reflect seismic waves due to associated variations in material properties, per Snell’s Law’ resulting in the generation of propagating surface waves in addition to the nearly-vertically propagating resonant shear waves ("body" waves).
These basin effects depend on the 3D geometry of the basin, which includes the shape, depth, orientation, and more, as well as the manner in which the seismic waves enter the basin.
Our group investigates the contributions of sedimentary basin amplification or de-amplification to the intensity and variability of seismic site effects in earthquake ground motions. We employ field recorded and physics-based simulated ground motion data to discern trends and high-fidelity features using statistical analysis and machine learning, which allow for the development of models for seismic demand characterization and hazard analysis.