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Improving Site Response Analysis for Earthquake Ground Motion Modeling


Shi, Jian (2019) Improving Site Response Analysis for Earthquake Ground Motion Modeling. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/X5NZ-DQ21.


The modeling of earthquake-induced ground motions plays an important role in the quantification of seismic hazards, which contributes to the ultimate goal of saving lives and reducing economic loss. Site response is a natural phenomenon in which soils in the earth’s shallow crust alter the amplitude, frequency content, and duration of earthquake-induced ground motions. Therefore, improvements in the research of site response directly contribute to ground motion modeling, and eventually to seismic hazard quantification.

This thesis presents two models that advance the current research in site response.

The first model provides a tool to predict near-surface shear-wave velocity profiles from Vs30 (a proxy that represents the general stiffness of a site). This model bridges the gap between the lack of information about near-surface soil properties and the need to model site response on a regional scale (city, county, or above).

The second model is a stress-strain model for describing 1D shearing behaviors of soils. It is capable of capturing both the small-strain and the large-strain behaviors, which makes it suitable for modeling very strong ground motions. More importantly, this model enables seismologists to construct stress-strain curves from only shear-wave velocity information, again improving our ability to model site response on a regional scale. Our validation study shows that this model outperforms the prevalent stress-strain model (namely, the MKZ model) by a considerable margin.

Lastly, we demonstrate how the two models above can improve earthquake ground motion modeling: we develop an improved version of site factors for the Western United States. These site factors are provided as Fourier spectral ratios, and phase factors are provided for the first time, which enables the time delay of earthquake waves to be modeled. They can be used for incorporating site response in earthquake ground motion simulations, as well as for improving seismic hazard maps for the Western United States.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Engineering Seismology, Earthquake Engineering, Site Response, Site Effect, Earthquake Ground Motion, Seismic Hazard
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Civil Engineering
Minor Option:Geophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Asimaki, Domniki
Thesis Committee:
  • Lapusta, Nadia (chair)
  • Andrade, Jose E.
  • Graves, Robert W.
  • Asimaki, Domniki
Defense Date:3 April 2019
Funding AgencyGrant Number
United States Geological Survey (USGS)G12AC20038
Charles Lee Powell FoundationUNSPECIFIED
Record Number:CaltechTHESIS:05302019-150220368
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 2. adapted for Chapter 3.
Shi, Jian0000-0002-1969-7579
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11571
Deposited By: Jian Shi
Deposited On:31 May 2019 19:31
Last Modified:28 Oct 2021 22:33

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