Earth Systems Science Computational Centre Publications  UQ eSpace
http://espace.library.uq.edu.au/
The University of Queensland
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Fez
http://blogs.law.harvard.edu/tech/rss

Computing threedimensional gravitational fields with equivalent sources
http://espace.library.uq.edu.au/view/UQ:139438
Existing techniques for computing the gravitational field due to a homogeneous polyhedron all transform the required volume integral, expressing the field due to a volume distribution of mass, into a surface integral, expressing the potential due to a surface mass distribution over the boundary of the source body. An alternative representation is also possible and results in a surface integral expressing the potential due to a variablestrength double layer located on the polyhedral source boundary. Manipulation of this integral ultimately allows the gravitational field component in an arbitrary direction to be expressed as a weighted sum of the potentials due to two basic source distributions. These are a uniformstrength double layer located on all faces and a uniformstrength line source located along all edges. The derivatives of the gravitational field components can also be expressed in a similar form as can the magnetic field components due to a homogeneous magnetic polyhedron. It follows that the present approach can be used to generate a universal program capable of modelling all the commonly used potential field responses due to 3D bodies of arbitrary shape.
20080610T10:38:20Z
Furness, Peter

Construction of an Intraplate Fault System Model of South Australia, and Simulation Tool for the iSERVO Institute Seed Project
http://espace.library.uq.edu.au/view/UQ:83360
To foster ongoing international cooperation beyond ACES (APEC Cooperation for Earthquake Simulation) on the simulation of solid earth phenomena, agreement was reached to work towards establishment of a frontier international research institute for simulating the solid earth: iSERVO = International Solid Earth Research Virtual Observatory institute (http://www.iservo.edu.au). This paper outlines a key Australian contribution towards the iSERVO institute seed project, this is the construction of: (1) a typical intraplate fault system model using practical fault system data of South Australia (i.e., SA interacting fault model), which includes data management and editing, geometrical modeling and mesh generation; and (2) a finiteelement based software tool, which is built on our longterm and ongoing effort to develop the Rminimum strategy based finiteelement computational algorithm and software tool for modelling threedimensional nonlinear frictional contact behavior between multiple deformable bodies with the arbitrarilyshaped contact element strategy. A numerical simulation of the SA fault system is carried out using this software tool to demonstrate its capability and our efforts towards seeding the iSERVO Institute.
20070815T10:58:36Z
Xing, H. L.; Mora, P. R.

Construction of an intraplate fault systems model of SOuth Australia, and simulation tool for the iSERVO institute seed project
http://espace.library.uq.edu.au/view/UQ:101692
20070823T20:20:29Z
Xing, H.; Mora, P. R.

Continental rifts: Complex dissipative patterns from simple boundary conditions
http://espace.library.uq.edu.au/view/UQ:255270
We present numerical models that investigate the development of crustal and mantle detachments during lithospheric extension. Our models, which consider an elastoviscoplastic lithosphere, explore the relationship between stored and dissipated energies during deformation. We apply the fundamental thermodynamic assumptions of minimization of Helmholtz free energy (i.e. stored energy) and maximization of dissipated energy, and include in the models feedback effects modulated by temperature, such as shear heating, that lead to strain localization. Our models simulate a wide range of extensional systems with varying values of crustal thickness and heat flow, showing how strain localization in the mantle interacts with localization in the upper crust and controls the evolution of extensional systems. Model results reveal a richness of structures and deformation styles as a response to a selforganized mechanism that minimizes the internal stored energy of the system by localizing deformation. Crustal detachments, here referred as lowangle normal decoupling horizons, are well developed during extension of overthickened (60 km) continental crust, even when the initial heat flow is relatively low (50 mW m2). In contrast, localized mantle deformation is most pronounced when the extended lithosphere has a normal crustal thickness (30–40 km) and an intermediate heat flow (60–70mWm2). Results show a nonlinear response to subtle changes in crustal thickness or heat flow, characterized by abrupt and sometimes unexpected switches in extension modes (e.g., from diffuse extensional deformation to effective lithosphericscale rupturing) or from mantleto crustdominated strain localization. We interpret this nonlinearity to result from the interference of doming wavelengths in the presence of multiple necking instabilities. Disharmonic crust and mantle doming wavelengths results in efficient communication between shear zones at different lithospheric levels, leading to rupturing of the whole lithosphere. In contrast, harmonic crust and mantle doming inhibits interaction of shear zones across the lithosphere and results in a prolonged history of extension prior to continental breakup.
20111012T17:00:25Z
Rosenbaum, Gideon; RegenauerLieb, Klaus; Weinberg, Roberto; Finzi, Yaron; Mühlhaus, Hans

Continuum Mechanics A & B and Exercises
http://espace.library.uq.edu.au/view/UQ:8552
The present manuscript is an updated version of the lecture notes I had used in 1993 for lectures at Gifu University and the TU Delft. I will update this introduction as the lecture evolves. At this stage I have revised Section 1 on Vectors and Tensors. The main difference to the previous manuscript is that I have taken out the subsection on covariant differentiation, Christoffel symbols etc in acknowledgement of the fact that if curvelinear coordinates are used it is usually either is in a numerical context (isoparametric finite elements), or one restricts oneself to cylindrical or spherical coordinates. In both cases the full differential calculus in curvelinear coordinates is not needed. However this does not mean that the ability to express geometric transformations in Lagrangian coordinates (which are curvelinear in general) is unnecessary. Quite the contrary, some of the basic geometric relationships derived in Section 1 will be very useful e.g. in the construction of constitutive relationships and the interpretation of various wellknown definitions of stress and strain tensors. Accordingly we begin with a brief representation of vectors, tensors in curvilinear coordinates, whereby the curvilinear coordinates are the deformed material coordinates. The present lecture series is again intended for students who have already had their first encounter with continuum mechanics. I begin with a brief representation of vectors, tensors and equations of motion in curvilinear coordinates, whereby the curvilinear coordinates may be the deformed material coordinates.
20060321T00:00:00Z
Muhlhaus, HansBernd

Convective instability of 3D fluidsaturated geological fault zones heated from below
http://espace.library.uq.edu.au/view/UQ:39590
We conduct a theoretical analysis to investigate the convective instability of 3D fluidsaturated geological fault zones when they are heated uniformly from below. In particular, we have derived exact analytical solutions for the critical Rayleigh numbers of different convective flow structures. Using these critical Rayleigh numbers, three interesting convective flow structures have been identified in a geological fault zone system. It has been recognized that the critical Rayleigh numbers of the system have a minimum value only for the fault zone of infinite length, in which the corresponding convective flow structure is a 2D slendercircle flow. However, if the length of the fault zone is finite, the convective flow in the system must be 3D. Even if the length of the fault zone is infinite, since the minimum critical Rayleigh number for the 2D slendercircle flow structure is so close to that for the 3D convective flow structure, the system may have almost the same chance to pick up the 3D convective flow structures. Also, because the convection modes are so close for the 3D convective flow structures, the convective flow may evolve into the 3D fingerlike structures, especially for the case of the fault thickness to height ratio approaching zero. This understanding demonstrates the beautiful aspects of the present analytical solution for the convective instability of 3D geological fault zones, because the present analytical solution is valid for any value of the ratio of the fault height to thickness. Using the present analytical solution, the conditions, under which different convective flow structures may take place, can be easily determined.
20070813T13:48:06Z
Zhao, C. B.; Hobbs, B. E.; Muhlhaus, H. B.; Ord, A.; Lin, G.

Correlation length evolution in cellular automata with longrange stress transfer
http://espace.library.uq.edu.au/view/UQ:96778
20070824T00:47:50Z
Wang, Y.; Mora, P. R.; Place, D. G.; Yin, X.

Correlation length evolution in cellular automata wtih longrange stress transfer
http://espace.library.uq.edu.au/view/UQ:149057
20080606T15:09:21Z
Weatherley, D. K.; Xia, M.; Mora, P. R.

Coulomb stress changes due to Queensland earthquakes and the implications for seismic risk assessment
http://espace.library.uq.edu.au/view/UQ:104987
20070823T22:44:51Z
Weatherley, D K

Cracks of higher modes in Cosserat continua
http://espace.library.uq.edu.au/view/UQ:107940
Rotational degrees of freedom in Cosserat continua give rise to higher fracture modes. Three new fracture modes correspond to the cracks that are surfaces of discontinuities in the corresponding components of independent Cosserat rotations. We develop a generalisation of J integral that includes these additional degrees of freedom. The obtained pathindependent integrals are used to develop a criterion of crack propagation for a special type of failure in layered materials with sliding layers. This fracture propagates as a progressive bending failure of layers – a “bending crack that is, a crack that can be represented as a distribution of discontinuities in the layer bending. This situation is analysed using a 2D Cosserat continuum model. Semiinfinite bending crack normal to layering is considered. The moment stress concentrates along the line that is a continuation of the crack and has a singularity of the power − 1/4. A model of process zone is proposed for the case when the breakage of layers in the process of bending crack propagation is caused by a crack (microcrack in our description) growing across the layer adjacent to the crack tip. This growth is unstable (in the momentcontrolled loading), which results in a typical descending branch of moment stress – rotation discontinuity relationship and hence in emergence of a Barenblatttype process zone at the tip of the bending crack.
20070827T12:58:23Z
Pasternak, E.; Dyskin, A. V.; Muhlhaus, HB.

Critical Point Systems, selforganised critically, and earthquake forecasting
http://espace.library.uq.edu.au/view/UQ:149058
20080606T15:09:24Z
Weatherley, D. K.; Jaume, S. C.; Mora, P. R.

Damage in stepovers may enable large cascading earthquakes
http://espace.library.uq.edu.au/view/UQ:279328
Seismic hazard analysis relies on the ability to predict whether an earthquake will terminate at a fault tip or propagate onto adjacent faults, cascading into a larger, more devastating event. While ruptures are expected to arrest at fault discontinuities larger than 4–5 km, scientists are often puzzled by much larger rupture jumps. Here we show that material properties between faults significantly affect the ability to arrest propagating ruptures. Earthquake simulations accounting for fault stepover zones weakened by accumulated damage provide new insights into rupture propagation. Revealing that lowered rigidity and material interfaces promote rupture propagation, our models show for the first time that stepovers as wide as 10 km may not constitute effective earthquake barriers. Our results call for reevaluation of seismic hazard analyses that predict rupture length and earthquake magnitude based on historic records and fault segmentation models.
20120827T08:47:37Z
Finzi, Y.; Langer, S.

Dating and geochemical tracing of paleoseismic events
http://espace.library.uq.edu.au/view/UQ:104780
20070823T22:36:17Z
Uysal, I. T.; Weatherley, D. K.; Zhao, J. X.; Golding, S. D.; Altunel, E.; Feng, Y.; Mutlu, H.; Karabacak, V.

Debrisflow deposits in an alluvialplain succession: The Upper Triassic Callide Coal Measures of Queensland, Australia
http://espace.library.uq.edu.au/view/UQ:143324
The CarnianRhaetian Callide Coal Measures are preserved in a small (22.5 km by 8 km), partially faultbounded basin remnant in eastcentral Queensland, Australia. The <150 m thick coalmeasure succession is interpreted to have accumulated during a phase of mild crustal extension that formed a series of discrete, intermontane basins in eastern Australia. The succession fines upward from a conglomeraterich lower part into a finergrained and coalbearing upper section (including coal seams <34 m thick), and is interpreted as the deposits of an alluvialplain environment. Anomalous, matrixrich diamictites, breccias, and conglomerates have been recognized within the succession at several localities, in many cases interbedded with coals. These are interpreted as the product of debris flows. Two debrisflow lithofacies are recognized: (1) mixtures of fine carbonaceous material, clay, silt, sand, gravel, and volcaniclastic debris, and (2) breccias consisting principally of coal clasts in a coaly matrix with minor clastic and volcaniclastic debris. Facies 1 is found in sharpbased, simple or composite bodies (<15 m thick) that are elongate to lobate in plan (with some multilobate), and as much as at least 1500 m long and 600 m wide. Facies 2 is less common and occurs in sharpbased units as much as 1.5 m thick, at least 200 m in length, and 60 m in width. Both facies are characterized by abundant fine matrix and a very poorly sorted clast population, and show little internal organization or sedimentary structure other than variably developed imbrication of coarse clasts. Parts of some bodies show an erosional base (with up to several meters of coal removed), although a flat, apparently nonerosional contact is more common. The distribution of debris flows in the Callide Coal Measures shows a coincidence with mapped faults and interpreted structural lineaments. The debris flows may have been triggered by fault movements, which formed rupture topography on the flat alluvial plain, and caused destabilization of watersaturated clastic and organic sediments. Some debrisflow bodies may have been mounded, such that subsequent peat formation was restricted until those bodies were buried. The preservation of debrisflow units at different stratigraphic levels along mapped structures suggests multiple paleoseismic events or multiple debrisflow events along those structures. The mixing of volcaniclastic debris into debrisflow facies suggests that seismic events were coincident with (or perhaps caused by) nearby, explosive volcanic activity. The close relationship between debrisflow deposits and thick coal bodies on the inferred downthrown sides of faults at Callide further suggests that periodic, tectonic subsidence may have facilitated thick coal accumulation.
20080610T14:12:17Z
Jorgensen, Peter J.; Fielding, Christopher R.

Deformation mechanism of the eastern Tibetan plateau: Insights from numerical models
http://espace.library.uq.edu.au/view/UQ:273479
20120430T20:55:45Z
Yao, Qi; Xu, XiWei; Xing, HuiLin; Zhang, Wei; Gao, Xiang

DEM Simulation of Rock Fragmentation and Size Distribution Under Different Loading Conditions
http://espace.library.uq.edu.au/view/UQ:177818
20090520T17:19:12Z
Wang, Y; AlonsoMarroquin, Fernando

Depositional environments for strata cored in CRP3 (Cape Roberts Project), Victoria Land Basin, Antarctica: palaeoglaciological and palaeoclimatological inferences
http://espace.library.uq.edu.au/view/UQ:58898
Cape Roberts Project drill core 3 (CRP3) was obtained from Roberts ridge, a seafloor high located at 77°S, 12 km offshore from Cape Roberts in western McMurdo Sound, Antarctica. The recovered core is about 939 m long and comprises strata dated as being early Oligocene (possibly latest Eocene) in age, resting unconformably on ∼ 116 m of basement rocks consisting of Palaeozoic Beacon Supergroup sediments. The core includes ten facies commonly occuring in five major associations that are repeated in particular sequences throughout the core and which are interpreted as representing different depositional environments through time. Depositional systems inferred to be represented in the succession include: outer shelf, inner shelf, nearshore to shoreface each under iceberg influence, deltaic and/or groundingline fan, and ice proximalice marginalsubglacial (mass flow/rainout diamictite/subglacial till) singly or in combination. The record is taken to represent the initial talus/alluvial fan setting of a glaciated rift margin adjacent to the blockuplifted Transantarctic Mountains. Development of a deltaic succession upcore was probably associated with the formation of palaeoMackay valley with temperate glaciers in its headwaters. At that stage glaciation was intense enough to support glaciers ending in the sea elsewhere along the coast, but a local glacier was fluctuating down to the sea by the time the youngest part of CRP3 was being deposited. Changes in palaeoenvironmental interpretations in this youngest part of the core are used to estimate relative glacial proximity to the drillsite through time. These inferred glacial fluctuations are compared with the global δ18O and Mg/Ca curves to evaluate the potential of glacial fluctuations on Antarctica for influencing these records of global change. Although the comparisons are tentative at present, the records do have similarities, but there are also some differences that require further evaluation.
20070814T15:26:56Z
Powell, R. D.; Laird, M. G.; Naish, T. R.; Fielding, C. R.; Krissek, L. A.; van der Meer, J. J. M.

Development of a Virtual Earth Simulator for Earthquake Microphysics: LSMearth
http://espace.library.uq.edu.au/view/UQ:149054
20080606T15:08:59Z
Place, D. G.; Mora, P. R.; Abe, S.

Discrete and continuous models for dry masonry columns
http://espace.library.uq.edu.au/view/UQ:57554
The dynamic response of dry masonry columns can be approximated with finitedifference equations. Continuum models follow by replacing the difference quotients of the discrete model by corresponding differential expressions. The mathematically simplest of these models is a onedimensional Cosserat theory. Within the presented homogenization context, the Cosserat theory is obtained by making ad hoc assumptions regarding the relative importance of certain terms in the differential expansions. The quality of approximation of the various theories is tested by comparison of the dispersion relations for bending waves with the dispersion relation of the discrete theory. All theories coincide with differences of less than 1% for wavelengthblockheight (L/h) ratios bigger than 2 pi. The theory based on systematic differential approximation remains accurate up to L/h = 3 and then diverges rapidly. The Cosserat model becomes increasingly inaccurate for L/h < 2 pi. However, in contrast to the systematic approximation, the wave speed remains finite. In conclusion, considering its relative simplicity, the Cosserat model appears to be the natural starting point for the development of continuum models for blocky structures.
20070813T16:44:37Z
Muhlhaus, HB; Sulem, J; Unterreiner, P

Discussion of Gorter & Glikson: Talundilly, Western Queensland, Australia: geophysical and petrological evidence for a 84 kmlarge structure and an Early Cretaceous impact cluster
http://espace.library.uq.edu.au/view/UQ:287380
20121216T00:43:24Z
Heidecker, E. J.

Distribution of climatic indicators in the Permian succession of the Bowen Basin, Australia
http://espace.library.uq.edu.au/view/UQ:149694
20080606T15:46:12Z
Jones, A.; Fielding, C. R.

Dorothy Hill, A.C., C.B.E.
http://espace.library.uq.edu.au/view/UQ:143697
20080610T14:32:50Z
Campbell, K. S. W.; Jell, J. S.

Double diffusiondriven convective instability of threedimensional fluidsaturated geological fault zones heated from below
http://espace.library.uq.edu.au/view/UQ:55553
We conduct a theoretical analysis to investigate the double diffusiondriven convective instability of threedimensional fluidsaturated geological fault zones when they are heated uniformly from below. The fault zone is assumed to be more permeable than its surrounding rocks. In particular, we have derived exact analytical solutions to the total critical Rayleigh numbers of the double diffusiondriven convective flow. Using the corresponding total critical Rayleigh numbers, the double diffusiondriven convective instability of a fluidsaturated threedimensional geological fault zone system has been investigated. The related theoretical analysis demonstrates that: (1) The relative higher concentration of the chemical species at the top of the threedimensional geological fault zone system can destabilize the convective flow of the system, while the relative lower concentration of the chemical species at the top of the threedimensional geological fault zone system can stabilize the convective flow of the system. (2) The double diffusiondriven convective flow modes of the threedimensional geological fault zone system are very close each other and therefore, the system may have the similar chance to pick up different double diffusiondriven convective flow modes, especially in the case of the fault thickness to height ratio approaching 0. (3) The significant influence of the chemical species diffusion on the convective instability of the threedimensional geological fault zone system implies that the seawater intrusion into the surface of the Earth is a potential mechanism to trigger the convective flow in the shallow threedimensional geological fault zone system.
20070813T15:22:47Z
Zhao, Chongbin; Hobbs, B. E.; Ord, A.; Peng, Shenglin; Muhlhaus, H. B.; Liu, Liangming

Drillingconstrained 3D gravity interpretation
http://espace.library.uq.edu.au/view/UQ:140743
In interpretation of gravity surveys, it is essential to exploit all the information available from drill holes in order to reduce the ambiguity. Accordingly, a new modelling and inversion methodology has been developed to expedite joint geological/geophysical interpretation of gravity data. The key features of the approach are the enforcement of drill constraints (pierce points) and the imposition of density bounds on geological formations and basement. 3D density models are constructed from closepacked vertical rectangular prisms with internal contacts. Prism tops honour topography, so that terrain effects are modelled, not 'corrected'. Detailed local models can be embedded in regional models to permit fitting of full freeair data, not residual gravity. The geological sense of models is preserved during inversion: the shape and density of homogeneous geological units are adjusted iteratively, subject to the drilling and density constraints. The methodology is illustrated using data from an advanced exploration project in South Australia. Integrated interpretation of a drilled area has been undertaken in four stages. The first stage entailed construction of a 'regional' density model, satisfying gridded gravity data on a coarse mesh over a large area centred on the drill grid. Next, a local density model was created on a fine mesh for the drill grid area, based on drill intercepts and density logs. Thirdly, the detailed density model was inserted into the regional model. Finally, constrained inversion was performed, to adjust the local starting model until a fit to the freeair gravity data was achieved.
20080610T11:44:25Z
Fullagar, P. K.; Hughes, N. A.; Paine, J.

Dynamic compexity in cellular automata with longrange stress transfer
http://espace.library.uq.edu.au/view/UQ:149060
20080606T15:09:31Z
Weatherley, D. K.; Xia, M.; Mora, P. R.

Dynamic rupture in a 3D particlebased simulation of a rough planar fault
http://espace.library.uq.edu.au/view/UQ:79920
An appreciation of the physical mechanisms which cause observed seismicity complexity is fundamental to the understanding of the temporal behaviour of faults and single slip events. Numerical simulation of fault slip can provide insights into fault processes by allowing exploration of parameter spaces which influence microscopic and macroscopic physics of processes which may lead towards an answer to those questions. Particlebased models such as the Lattice Solid Model have been used previously for the simulation of stickslip dynamics of faults, although mainly in two dimensions. Recent increases in the power of computers and the ability to use the power of parallel computer systems have made it possible to extend particlebased fault simulations to three dimensions. In this paper a particlebased numerical model of a rough planar fault embedded between two elastic blocks in three dimensions is presented. A very simple friction law without any rate dependency and no spatial heterogeneity in the intrinsic coefficient of friction is used in the model. To simulate earthquake dynamics the model is sheared in a direction parallel to the fault plane with a constant velocity at the driving edges. Spontaneous slip occurs on the fault when the shear stress is large enough to overcome the frictional forces on the fault. Slip events with a wide range of event sizes are observed. Investigation of the temporal evolution and spatial distribution of slip during each event shows a high degree of variability between the events. In some of the larger events highly complex slip patterns are observed.
20070815T08:39:33Z
Abe, S; Latham, S; Mora, P

Dynamics of slab tear faults: Insights from numerical modelling
http://espace.library.uq.edu.au/view/UQ:203322
Tear resistance at the edge of a slab is an important parameter controlling the evolution of subduction zones. However, compared with other subduction parameters such as plate strength, plate viscosity, plate thickness and trench width, the dynamics of tearing are poorly understood. Here we obtain a firstorder understanding of the dynamics and morphology of subduction zones to resistance during tear propagation, by developing and using a novel computational modelling technique for subducting slabs, with side boundaries described by viscoplastic weak zones, developing into tear faults. Our 3D model is based upon a viscoplastic slab that sinks into the less dense mantle, generating poloidal and toroidal flows. The asthenospheric mantle field is static and only develops flow due to the subducting slab. We use the finite element code eScript/Finley and the level set method to describe the lithosphere to solve this fluid dynamics problem. Our results show the importance of tear resistance for the speed of trench migration and for shaping the final geometry of subduction systems. We show that slab tearing along a weak layer can result in a relatively straight slab hinge shape, while increasing the strength in the weak layer results in the curvature of the hinge increasing substantially. High tear resistance at the slab edges may hinder rollback to the extent that the slab becomes stretched and recumbently folded at the base of the domain. Tear resistance also controls whether the subducting lithosphere can experience accelerating rollback velocities or a constant rollback velocity. © 2009 Elsevier B.V. All rights reserved.
20100418T00:00:54Z
Hale, Alina J.; Gottschaldt, Klaus D.; Rosenbaum, Gideon; Bourgouin, Laurent; Bauchy, Matthieu; Muhlhaus, Hans B.

Earthquake forecasting: retrospective studies in Australia  The Newcastle and Burra earthquakes  and numberical simulation of the physical process
http://espace.library.uq.edu.au/view/UQ:149049
20080606T15:08:42Z
Mora, P. R.; Place, D. G.; Wang, Y.; Peng, K.; Weatherley, D.

Earthquake processes: Physical modelling, numerical simulation and data analysis  Part I
http://espace.library.uq.edu.au/view/UQ:115480
20071017T11:30:34Z
Matsu'ura, M.; Mora, P.; Donnellan, A.; Yin, X. C.

Earthquake Processes: Physical Modelling, Numerical Simulation and Data Analysis Part II
http://espace.library.uq.edu.au/view/UQ:94207
20070822T10:18:04Z

Earthquakes : Simulations, Sources and Tsunamis
http://espace.library.uq.edu.au/view/UQ:174779
20090408T19:57:30Z
Tiampo, K.F.; Weatherley, Dion K.; Weinstein, S.A.

Earthquake trend around Sumatra indicated by a New Implementation of LURR Method
http://espace.library.uq.edu.au/view/UQ:174777
The current implementation of LURR (Load/Unload Response Ratio) theory has shown promise in intermediate to shortterm earthquake forecasting through past practice, but has also met difficulties at the same time. In this paper a new implementation of LURR method is presented to address one of the problems. The major change in the new implementation is that LURR values will result from a calculated maximum faulting orientation (MFO) instead of any focal mechanism selected by users. After comparison with the world stress map, the calculated MFO has been found to be in good agreement with the observation from the regional tectonic stress regime. The MFO pattern in the Indonesia region has a special feature which may be related to the unique subduction complexity. The MFO pattern in the Sumatra region in general is different from that in the Java region after the 2004 M 9.0 Sumatra Andaman Islands earthquake. This phenomenon may be supported by the evidence of the recent observation that a section in the southern part of the Sumatran arc is locked. Furthermore, the MFO pattern before the 2004 main shock is different from that after the event. Retrospective examination of the Indonesia region by means of this implementation can produce significant LURR anomaly not only prior to the 2004 main shock but also before the 2006 M 7.7 South Java earthquake. Therefore future great earthquakes might favorably be forecasted if the LURR anomaly detected by MFO method could be considered a precursor.
20090408T19:47:48Z
Yin, Can; Xing, Huilin; Mora, Peter; Xu, Hehua

Earthquake trend around Sumatra region indicated by a new LURR implementation
http://espace.library.uq.edu.au/view/UQ:131024
20080219T14:21:27Z
Yin, C.; Xing, H.; Mora, P. R.; Xu, H.

Earth Systems simulations on SGI Altix systems using Python
http://espace.library.uq.edu.au/view/UQ:103196
20070823T21:25:21Z
Gross, L.; Cochrane, P. T.; Davies, M.; Muhlhaus, H. B.; Smillie, J. G.

Effect of material anisotropy on the onset of convective flow in threedimensional fluidsaturated faults
http://espace.library.uq.edu.au/view/UQ:39110
In order to investigate the effect of material anisotropy on convective instability of threedimensional fluidsaturated faults, an exact analytical solution for the critical Rayleigh number of threedimensional convective flow has been obtained. Using this critical Rayleigh number, effects of different permeability ratios and thermal conductivity ratios on convective instability of a vertically oriented threedimensional fault have been examined in detail. It has been recognized that (1) if the fault material is isotropic in the horizontal direction, the horizontal to vertical permeability ratio has a significant effect on the critical Rayleigh number of the threedimensional fault system, but the horizontal to vertical thermal conductivity ratio has little influence on the convective instability of the system, and (2) if the fault material is isotropic in the fault plane, the thermal conductivity ratio of the fault normal to plane has a considerable effect on the critical Rayleigh number of the threedimensional fault system, but the effect of the permeability ratio of the fault normal to plane on the critical Rayleigh number of threedimensional convective flow is negligible.
20070813T13:30:19Z
Zhao, CB; Hobbs, BE; Ord, A; Muhlhaus, HB; Lin, G

Effect of rolling on dissipation in fault gouges
http://espace.library.uq.edu.au/view/UQ:83392
Sliding and rolling are two outstanding deformation modes in granular media. The first one induces frictional dissipation whereas the latter one involves deformation with negligible resistance. Using numerical simulations on twodimensional shear cells, we investigate the effect of the grain rotation on the energy dissipation and the strength of granular materials under quasistatic shear deformation. Rolling and sliding are quantified in terms of the socalled Cosserat rotations. The observed spontaneous formation of vorticity cells and clusters of rotating bearings may provide an explanation for the long standing heat flow paradox of earthquake dynamics.
20070815T10:59:51Z
AlonsoMarroquin, F.; Vardoulakis, I.; Herrmann, H. J.; Weatherley, D.; Mora, P.

Effects of a noncoaxial flow rule on shear bands in viscousplastic materials
http://espace.library.uq.edu.au/view/UQ:255433
20111013T10:21:28Z
Muhlhaus, Hans B.; Shi, Jingyu; OlsenKettle, Louise; Moresi, Louis

Effects of geological inhomogeneity on high Rayleigh number steady state heat and mass transfer in fluidsaturated porous media heated from below
http://espace.library.uq.edu.au/view/UQ:34766
A parametric study is carried out to investigate how geological inhomogeneity affects the porefluid convective flow field, the temperature distribution, and the mass concentration distribution in a fluidsaturated porous medium. The related numerical results have demonstrated that (1) the effects of both medium permeability inhomogeneity and medium thermal conductivity inhomogeneity are significant on the porefluid convective flow and the species concentration distribution in the porous medium; (2) the effect of medium thermal conductivity inhomogeneity is dramatic on the temperature distribution in the porous medium, but the effect of medium permeability inhomogeneity on the temperature distribution may be considerable, depending on the Rayleigh number involved in the analysis; (3) if the coupling effect between porefluid flow and mass transport is weak, the effect of the Lewis number is negligible on the porefluid convective flow and temperature distribution, hut it is significant on the species concentration distribution in the medium.
20070813T10:24:13Z
Zhao, CB; Muhlhaus, HB; Hobbs, BE

Effects of hot intrusions on porefluid flow and heat transfer in fluidsaturated rocks
http://espace.library.uq.edu.au/view/UQ:39186
We use the finite element method to solve coupled problems between porefluid flow and heat transfer in fluidsaturated porous rocks. In particular, we investigate the effects of both the hot pluton intrusion and topographically driven horizontal flow on the distributions of the poreflow velocity and temperature in largescale hydrothermal systems. Since general mineralization patterns are strongly dependent on distributions of both the porefluid velocity and temperature fields, the modern mineralization theory has been used to predict the general mineralization patterns in several realistic hydrothermal systems. The related numerical results have demonstrated that: (1) The existence of a hot intrusion can cause an increase in the maximum value of the porefluid velocity in the hydrothermal system. (2) The permeability of an intruded pluton is one of the sensitive parameters to control the porefluid flow, heat transfer and ore body formation in hydrothermal systems. (3) The maximum value of the porefluid velocity increases when the bottom temperature of the hydrothermal system is increased. (4) The topographically driven flow has significant effects on the porefluid flow, temperature distribution and precipitation pattern of minerals in hydrothermal systems. (5) The size of the computational domain may have some effects on the porefluid flow and heat transfer, indicating that the size of a hydrothermal system may affect the porefluid flow and heat transfer within the system. (C) 2003 Elsevier Science B.V. All rights reserved.
20070813T13:33:21Z
Zhao, CB; Lin, G; Hobbs, BE; Ord, A; Wang, YJ; Muhlhaus, HB

Effects of medium thermoelasticity on high Rayleigh number steadystate heat transfer and mineralization in deformable fluidsaturated porous media heated from below
http://espace.library.uq.edu.au/view/UQ:35545
In this paper, a solution method is presented to deal with fully coupled problems between medium deformation, porefluid flow and heat transfer in fluidsaturated porous media having supercritical Rayleigh numbers. To validate the present solution method, analytical solutions to a benchmark problem are derived for some special cases. After the solution method is validated, a numerical study is carried out to investigate the effects of medium thermoelasticity on high Rayleigh number steadystate heat transfer and mineralization in fluidsaturated media when they are heated from below. The related numerical results have demonstrated that: (1) medium thermoelasticity has a little influence on the overall pattern of convective porefluid flow, but it has a considerable effect on the localization of medium deformation, porefluid flow, heat transfer and mineralization in a porous medium, especially when the porous medium is comprised of soft rock masses; (2) convective porefluid flow plays a very important role in the localization of medium deformation, heat transfer and mineralization in a porous medium. (C) 1999 Elsevier Science S.A. All rights reserved.
20070813T11:04:07Z
Zhao, CB; Hobbs, BE; Muhlhaus, HB

Efficient implementation of complex particle shapes in the Lattice Solid Model
http://espace.library.uq.edu.au/view/UQ:98357
20070824T01:53:51Z
Abe, S.; Mora, P. R.

Efficient implementation of complex particle shapes in the lattice solid model
http://espace.library.uq.edu.au/view/UQ:116294
The lattice solid model is a particle based simulation model for the study of earthquake microphysics and rock mechanics. It consists of particles interacting by various types of mechanisms such as elasticbrittle forces and friction. Results of laboratory experiments have shown that the grain shape has a major influence on the frictional properties of fault gouge. In order to enable realistic simulations it is thus important to include the capability to model nonspherical particles into the simulation software. To achieve this goal a new class of particles with variable shapes have been implemented in the lattice solid model. The shape of the particles is described by an arbitrary number of piecewise spherical patches. This leads to a good balance between the computational cost of the contact detection and calculation of interactions between particles and the range of particle shapes available.
20071017T12:13:49Z
Abe, S.; Mora, P. R.

Efficient solvers for incompressible fluid flows in geosciences
http://espace.library.uq.edu.au/view/UQ:152725
Saddle point problems involving large systems of linear equations arise in a wide variety of applications in computational science and engineering. A variety of solvers have been developed for these type of problems typically with specific applications in mind. In this paper we will focus on saddle point problems as they arise from incompressible ﬂuid ﬂow problems in applications in geosciences. They are characterized through a spatially variable viscosity when modeling temperature dependencies (e.g. in Earth mantel convection models) or moving material interfaces (e.g. in subduction zones simulation and numerical volcano models). In this paper we will give an overview on some of the iterative techniques that can be used and discuss suitable preconditioning techniques. We will discuss the implementation of the schemes using the python module Escript and compare the efficiency of these schemes when applied to convection models on a parallel computer.
20080818T13:43:02Z
Amirbekyan, A.; Gross, L.

Ejection landslide at northern terminus of beichuan rupture triggered by the 2008 Mw 7.9 Wenchuan earthquake
http://espace.library.uq.edu.au/view/UQ:219981
20101107T00:15:02Z
Yuan, RenMao; Xu, XiWei; Chen, GuiHua; Tan, XiBin; Klinger, Yann; Xing, HuiLin

Elasticity and strength of partially sintered ceramics
http://espace.library.uq.edu.au/view/UQ:255921
A discrete element model for the elastic and fracture behavior of partially sintered ceramics is presented. It accounts for the granular character of the material when a large amount of porosity (typically >0.2–0.4) is left after sintering. The model uses elastic forcedisplacement laws to represent the bond formed between particles during sintering. Bond fracture in tension and shearing is accounted for in the model. Realistic numerical microstructures are generated using a sintering model on random particle packings. In particular, packings with fugitive pore formers are used to create partially sintered microstructures with large pores. The effective elastic response and the strength of these microstructures are calculated in tension and compression. The link between important microstructural features such as bond size or coordination number and macroscopic behavior is investigated. In particular, it is shown that porosity alone is not sufficient to account for the mechanical properties of a partially sintered material.
20111014T08:27:25Z
Liu, Xiaoxing; Matin, Christophe; Delette, Gerard; Bouvard, Didier

Elasticity, Yielding and Episodicity in Simple Models of Mantle Convection
http://espace.library.uq.edu.au/view/UQ:9142
We explore the implications of refinements in the mechanical description of planetary constituents on the convection modes predicted by finite element simulations. The refinements consist in the inclusion of incremental elasticity, plasticity (yielding) and multiple simultaneous creep mechanisms in addition to the usual viscoplastic models employed in the context of unified platemantle models. The main emphasis of this paper rests on the constitutive and computational formulation of the model. We apply a consistent incremental formulation of the nonlinear governing equations avoiding the computationally expensive iterations that are otherwise necessary to handle the onset of plastic yield. In connection with episodic convection simulations, we point out the strong dependency of the results on the choice of the initial temperature distribution. Our results also indicate that the inclusion of elasticity in the constitutive relationships lowers the mechanical energy associated with subduction events.
20051007T00:00:00Z
Muhlhaus, HansBernd; Davies, Matt; Moresi, Louis

Elasticity, yielding and episodicity in simple models of mantle convection
http://espace.library.uq.edu.au/view/UQ:101618
20070823T20:17:35Z
Muhlhaus, H. B.; Davies, M.; Gross, L.; Moresi, L.

Elasticity, Yielding and episodicity in simple models of mantle convection
http://espace.library.uq.edu.au/view/UQ:101678
20070823T20:20:01Z
Muhlhaus, H. B.; Davies, M.; Gross, L.; Moresi, L.

Elasticity, yielding and episodicity in simple models of mantle convection
http://espace.library.uq.edu.au/view/UQ:83401
We explore the implications of refinements in the mechanical description of planetary constituents on the convection modes predicted by finiteelement simulations. The refinements consist in the inclusion of incremental elasticity, plasticity (yielding) and multiple simultaneous creep mechanisms in addition to the usual viscoplastic models employed in the context of unified platemantle models. The main emphasis of this paper rests on the constitutive and computational formulation of the model. We apply a consistent incremental formulation of the nonlinear governing equations avoiding the computationally expensive iterations that are otherwise necessary to handle the onset of plastic yield. In connection with episodic convection simulations, we point out the strong dependency of the results on the choice of the initial temperature distribution. Our results also indicate that the inclusion of elasticity in the constitutive relationships lowers the mechanical energy associated with subduction events.
20070815T11:00:09Z
Muhlhaus, HansBernd; Davies, Matt; Moresi, Louis

Elastodynamic simulation of fault system dynamics
http://espace.library.uq.edu.au/view/UQ:98359
20070824T01:53:55Z
Mora, P. R.; Weatherley, D. K.