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Ground Motions Simulated on 3D Printed Earth Models

Session: Advances in Understanding Near-Field Ground Motions: Observation, Prediction and Application I

Type: Oral

Date: 4/22/2021

Presentation Time: 09:45 AM Pacific

Description: 

Complex structure such as small-scale heterogeneities, rough topography and basin interfaces can significantly amplify the ground motion. Understanding the path and site effects caused by such small-scale features is particularly important for near-field scenarios where abundant high-frequency energy is present. However, challenges arise not only from the limitations in computing resources, but also from inaccuracies in forward models and approximations that are being imposed in numerical studies.

Here, we present a novel physical modeling approach to understand near-field ground motions. We take advantage of 3D printing techniques to create physical models for seismic experiments. We mainly use metal as the 3D printing material since it can represent material properties as rigid as the Earth’s lower crust. By adjusting the printing parameters, i.e., the laser power and the scanning speed, during the printing process, we change the density structure within a printed model. This approach allows us to effectively represent a broad range of material properties, e.g., P-wave speeds of about 1-6 km/s. Based on the relationship between the printing parameters and seismic wave speeds, seismic velocity models with different levels of complexity are printed, including a basin model derived from a southern­­ California velocity model (CVM-H model). We perform seismic experiments on the 3D printed models using laser generators and laser doppler vibrometers as sources and receivers. The experiments result in record sections where a variety of seismic phases, e.g., direct and reflected body and surface waves, are identified. The measured travel times of major phases are consistent with predictions based on the input velocity models. We also “simulate” a local earthquake in the Los Angeles basin area and find ground motion amplified by shallow basin structure, in particular, in the vicinity of the basin edges. Our study demonstrates that seismic experiments on 3D printed Earth models provide unprecedented opportunities of understanding seismic ground motions.

Presenting Author: Sunyoung Park

Student Presenter: No

Authors