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Seismogenesis and the time dependenc...

Raphael, Andrea Joy.

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Seismogenesis and the time dependence of crustal strength.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Seismogenesis and the time dependence of crustal strength./
Author:	Raphael, Andrea Joy.
Description:	214 p.
Notes:	Adviser: Paul Bodin.
Contained By:	Dissertation Abstracts International67-09B.
Subject:	Geophysics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3230971
ISBN:	9780542853852

Seismogenesis and the time dependence of crustal strength.
Raphael, Andrea Joy.

Seismogenesis and the time dependence of crustal strength. - 214 p.

Adviser: Paul Bodin.

Thesis (Ph.D.)--The University of Memphis, 2006.

This dissertation explores the control of earthquake occurrence by crusta rheology, both at steady-state and when crustal conditions are perturbed following a large earthquake. The physical mechanisms that are thought to control a rock's ultimate strength and to determine the manner in which it fails have traditionally been used to produce one-dimensional "crustal strength profiles". These models lead to specific predictions about the depths at which brittle failure (i.e. earthquakes) may be observed in a region. These deterministic models are based on uncertain extrapolations from laboratory studies, and do not account for heterogeneity and variability the in Earth. In order to incorporate these uncertainties, and to determine the usefulness of constraints that earthquake occurrence places on simple rheological models, I followed two basic steps. First, I designed an algorithm to construct "probabilistic" crustal strength profiles and second I evaluate earthquake depth distributions from various tectonic settings. The computer algorithm, strength, uses a Monte Carlo simulation to construct a series of strength profiles from distributions of physical and geological parameters that span the range of values reflected by real uncertainties. This model yields the probability, at any depth, that failure would be either brittle (resulting in earthquakes) or ductile (aseismic deformation). These probabilities are compared to actual earthquake depth distributions (subject to their own uncertainties). Comparisons were undertaken both in regions that are deforming slowly and in areas with recent large earthquakes and periods rapid post-seismic strain to study whether and how the depth extent of seismicity changes after a large earthquake. Earthquake depths within the steady-state regions, and for pre-mainshock periods, could to first order be explained by the models. The post-mainshock modeling predicted that the seismicity cut-off should deepen temporarily because of a transient increase in strain rate. While this was observed in some sub-regions of the aftershock zones, in other sub-regions the seismicity cutoff became shallower following the mainshock. Failure of the model in some sub-regions suggests that strength models may be oversimplifying the true heterogeneity of properties and/or deformational mechanisms in Earth.

ISBN: 9780542853852Subjects--Topical Terms:

535228
Geophysics.

Seismogenesis and the time dependence of crustal strength.
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005 20110915
008 110915s2006 eng d
020 $a 9780542853852
035 $a (UnM)AAI3230971
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040 $a UnM $c UnM
100 1 $a Raphael, Andrea Joy. $3 1291064
245 1 0 $a Seismogenesis and the time dependence of crustal strength.
300 $a 214 p.
500 $a Adviser: Paul Bodin.
500 $a Source: Dissertation Abstracts International, Volume: 67-09, Section: B, page: 4942.
502 $a Thesis (Ph.D.)--The University of Memphis, 2006.
520 $a This dissertation explores the control of earthquake occurrence by crusta rheology, both at steady-state and when crustal conditions are perturbed following a large earthquake. The physical mechanisms that are thought to control a rock's ultimate strength and to determine the manner in which it fails have traditionally been used to produce one-dimensional "crustal strength profiles". These models lead to specific predictions about the depths at which brittle failure (i.e. earthquakes) may be observed in a region. These deterministic models are based on uncertain extrapolations from laboratory studies, and do not account for heterogeneity and variability the in Earth. In order to incorporate these uncertainties, and to determine the usefulness of constraints that earthquake occurrence places on simple rheological models, I followed two basic steps. First, I designed an algorithm to construct "probabilistic" crustal strength profiles and second I evaluate earthquake depth distributions from various tectonic settings. The computer algorithm, strength, uses a Monte Carlo simulation to construct a series of strength profiles from distributions of physical and geological parameters that span the range of values reflected by real uncertainties. This model yields the probability, at any depth, that failure would be either brittle (resulting in earthquakes) or ductile (aseismic deformation). These probabilities are compared to actual earthquake depth distributions (subject to their own uncertainties). Comparisons were undertaken both in regions that are deforming slowly and in areas with recent large earthquakes and periods rapid post-seismic strain to study whether and how the depth extent of seismicity changes after a large earthquake. Earthquake depths within the steady-state regions, and for pre-mainshock periods, could to first order be explained by the models. The post-mainshock modeling predicted that the seismicity cut-off should deepen temporarily because of a transient increase in strain rate. While this was observed in some sub-regions of the aftershock zones, in other sub-regions the seismicity cutoff became shallower following the mainshock. Failure of the model in some sub-regions suggests that strength models may be oversimplifying the true heterogeneity of properties and/or deformational mechanisms in Earth.
590 $a School code: 1194.
650 4 $a Geophysics. $3 535228
690 $a 0373
710 2 0 $a The University of Memphis. $3 1025952
773 0 $t Dissertation Abstracts International $g 67-09B.
790 $a 1194
790 1 0 $a Bodin, Paul, $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3230971