Electronic Theses and Dissertations

Identifier

6317

Date

2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Civil Engineering

Committee Chair

Shahram Pezeshk

Committee Member

Martin Chapman

Committee Member

Chris Cramer

Committee Member

Roger W. Meier

Committee Member

Sabya Mishra

Committee Member

Behrooz Tavakoli

Abstract

Central and eastern North America (CENA) is considered to be a moderately active region, but it suffers from a lack of recorded earthquakes in the magnitude-distance range of engineering interest. In this dissertation, region-specific synthetic strong ground motion time histories are generated using a new and improved stochastic summation of Green's functions method (SSGFM) for CENA. In addition, the synthetics are used to develop ground motion prediction equations (GMPEs) for this region. For simulating large earthquakes, considering the effects of finite-fault rupture such as rupture propagation, asperities, and fault-site geometry (saturation effect) are significant and influential. The SSGFM is a straightforward approach in which the effect of rupture propagation is stochastically taken into account by summation over many lagged small earthquakes, without requiring any detailed information about the rupture process such as rise time, slip distribution, rupture speed, and dimensions of the fault. The summation procedure is defined to match the spectrum of the target event satisfying the scaling law of the source spectra. The effect of asperities on waveforms is brought into play by using a two-stage summation scheme through simulations. Since the concept of the source in the SSGFM developed in this dissertation is point source, the distance defined in its framework is the distance between the site and an equivalent point source, called effective distance, in which the impact of the propagation path on seismic waves radiated from different parts of the fault is considered. However, motions come from different parts of the fault rupture in the extended source model, not a single point. I will improve the SSGFM to convert the effective distance to the Joyner-Boore distance, which is one the most-used distance metrics in the engineering and seismology fields, for a given fault size within a region with given geometrical spreading and attenuation functions. Further, I will improve the summation scheme of the SSGFM to define the source spectrum of large earthquakes with double-corner frequency models.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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