Effects of the Los Angeles Basin on Ground Motion Studied Using Lab Experiments on a 3D-printed Model
Despite extensive research using numerical modeling approaches, it remains challenging to simulate ground motions in the presence of small-scale features such as sedimentary basins. High-frequency ground motions that are greatly affected by the basin structure are particularly difficult to simulate; instead, they are often approximated using stochastic approaches. Such challenges in numerical methods limit our understanding of basin effects. Particularly, the 3D basin effects, i.e., consideration of the volume and shape of basins, irregular basin edges, and laterally varying basin depths, need further investigations.
We introduce a new lab-based method of ground motion simulation. We (1) build a physical model based on the Los Angeles Basin structure using the 3D printing technique and (2) conduct seismic experiments on the model by generating artificial “quakes” and measuring displacements, using a pulsed laser as seismic sources and a laser doppler vibrometer as receivers. Small-scale heterogeneities such as shallow sedimentary basins with low velocities and complex interfaces are reproduced by adjusting the speed of the 3D printing: the faster the speed, the lower the density and slower the wave speed. The velocity model contains a shallow basin with laterally varying depths between 150m and 1.5km (printed at 1:260,000 ratio). Recorded data show P and surface wave arrivals that are consistent with the input velocity model. We also observe the effects of the sedimentary basin on the ground motions. The edge of the basin reflects and scatters P and surface waves, even when their wavelengths are more than five times longer than the basin depth (150m). Likely due to the reflections, high-frequency energies are relatively reduced inside the sedimentary basin. We also present time-domain analyses on the peak ground displacement (PGD) using our displacement field recordings.
Session: The Effects of Sedimentary Basins on Earthquake Ground Motions II
Type: Oral
Room: Cedar
Date: 4/20/2022
Presentation Time: 05:00 PM Pacific
Presenting Author: Jiong Wang
Student Presenter: No
Additional Authors
Jiong Wang Presenting Author Corresponding Author jiongwang@uchicago.edu The University of Chicago |
Sunyoung Park sunnypark@uchicago.edu The University of Chicago |
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Effects of the Los Angeles Basin on Ground Motion Studied Using Lab Experiments on a 3D-printed Model
Category
The Effects of Sedimentary Basins on Earthquake Ground Motions
Description