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Recent studies in the literature have introduced a new approach to earthquake forecasting based on representing the space-time patterns of localized seismicity by a time-dependent system state vector in a real-valued Hilbert space and deducing information about future space-time fluctuations from the phase angle of the state vector. While the success rate of this Pattern Informatics (PI) method has been encouraging, the method is still in its infancy. Procedural analysis, statistical testing, parameter sensitivity investigation and optimization all still need to be performed. In this paper, we attempt to optimize the PI approach by developing quantitative values for "predictive goodness" and analyzing possible variations in the proposed procedure. In addition, we attempt to quantify the systematic dependence on the quality of the input catalog of historic data and develop methods for combining catalogs from regions of different seismic rates. [ABSTRACT FROM AUTHOR]

Seismogenic process is a nonlinear and irreversible one, so that the response to loading of a seismogenic zone is different from the unloading one. This difference reflects quantitatively the process of an earthquake preparation. A physics-based new parameter-Load/Unload Response Ratio (LURR) was proposed to measure quantitatively the proximity to a strong earthquake and then used to be an earthquake predictor. In the present paper, a brief history of LURR is recalled; inspection of real earthquake cases, numerical simulations and laboratory studies of LURR, prediction efforts in terms of LURR, probability problem of LURR and its prospect are also expatiated. [ABSTRACT FROM AUTHOR]

The Pattern Informatics (PI) technique (Tiampo et al., 2002) is founded on the premise that changes in the seismicity rate are a proxy for changes in the underlying stress. These stress changes are correlated over large spatial regions, and can be quantified using a phase dynamical analysis of the changes in historic seismicity rates. This new approach to the study of seismicity quantifies its local and regional space-time patterns and identifies regions of local quiescence or activation. Here we study those local changes in an attempt to objectively quantify short-term stress shadow regions. We determine that, while persistent stress shadows are detectable with this method, they do not occur uniformly throughout the spatio-temporal region. [ABSTRACT FROM AUTHOR]

Geological sequestration of CO2 (carbon dioxide) shows great potential to reduce Greenhouse gas emissions. However, CO2 injection into geological formations may give rise to a variety of coupled chemical and physical processes. The thermo-hydro-mechanical (THM) impact of CO2 injection can induce fault instability, even possibly lead to seismic activities in and around the disposal reservoir. A sequential coupling approach under some assumptions was proposed in the numerical study to investigate the THM behavior of the CO2 sequestration system concerning the temperature, initial geological stress, injection pressure and CO2 buoyancy. The fault was treated as a flexible contact model. The effects of CO2 injection on the mechanical behavior of the faults were investigated. The Drucker-Prager model and the cap model were used to model the constitutive relationship of formations. The numerical results show that injection pressure sensitively affects the relative slip change of the fault. At the initial stage of the sequestration process, the injection pressure plays a key role in affecting the pore pressure of the formations. However, as time continues, the influence of CO2-induced buoyancy becomes obvious on the pore pressure of the formations. In general, The THM effects of CO2 geosequestration do not affect the mechanical stability of formations and faults. [ABSTRACT FROM AUTHOR]

The general characteristics of the recent horizontal crustal movement in the Chinese Mainland and the horizontal crustal movements before the Kunlun Mountain earthquake of M8.1 on Nov. 14, 2001 and two earthquakes of M 8.0 and M 7.9 occurred in Sept. 2003 around the Chinese Mainland are analyzed with GPS data obtained in the Crustal Movement Observation Network of China (CMONOC). Relative vertical displacements observed in the last five years at fiducial stations show that there was a significant correlation between the length of day and the vertical displacements at most stations in western China. [ABSTRACT FROM AUTHOR]

The concept of state vector stems from statistical physics, where it is usually used to describe activity patterns of a physical field in its manner of coarsegrain. In this paper, we propose an approach by which the state vector was applied to describe quantitatively the damage evolution of the brittle heterogeneous systems, and some interesting results are presented, i.e., prior to the macro-fracture of rock specimens and occurrence of a strong earthquake, evolutions of the four relevant scalars time series derived from the state vectors changed anomalously. As retrospective studies, some prominent large earthquakes occurred in the Chinese Mainland (e.g., the M 7.4 Haicheng earthquake on February 4, 1975, and the M 7.8 Tangshan earthquake on July 28, 1976, etc) were investigated. Results show considerable promise that the time-dependent state vectors could serve as a kind of precursor to predict earthquakes. [ABSTRACT FROM AUTHOR]

In order to study the earthquake recurrence and the characteristics of earthquake series, rupture tests of rock samples and plexiglass samples were made. On rock samples, a number of acoustic emission (AE) and strain measuring points were deployed; the load was one side direct shear. The variation characteristics of AE and strain at different detecting points around the extra large fracture were observed and studied. On plexiglass samples, a series of inclined cracks were prefabricated by a small-scale compressive testing machine. The samples were then loaded on a shockproof platen, when the samples were loaded, the stress intensity factor (SIF) was determined by the laser interferometric technique and shadow optical method of caustics. The fracture conditions such as material toughness around the extralarge fracture were also studied. From those experimental results and the theory of fracture mechanics, the earthquake recurrence period and the trend of post-seismic development were studied. [ABSTRACT FROM AUTHOR]

A general formulation of the Helmholtz free energy used in thermodynamics of damage process of rocks is derived within a multi-scale framework. Such a physically-based thermodynamic state potential has a hybrid, discrete/continuum, nature in the sense that it adopts a continuum description but subsumes the statistical ensemble average of the action of the entirety of microscopic degrees of freedom. The choice of the relevant damage variables results therefore directly from the breaking of contact cohesive bonds, and it naturally obeys the Clausius-Duhem inequality. Furthermore, motivated by the fact that the free energy is formulated by the integral of potentials independently defined on different orientations over the upper hemisphere, the damage evolution equation is formulated on a generic orientation. Consequently, the mechanical behavior of a rock material generally becomes anisotropic characteristics in the inelastic regime even if the material is initially isotropic, thus introducing dissipation-induced anisotropy in a very natural and simple way. Finally, the development of the lattice solid model can be cast into the framework of the orientation based continuum constitutive model. [ABSTRACT FROM AUTHOR]

In this paper, 28 aftershock sequences are selected, which are distributed in different areas including north China, southwest of China, northwest of China, Taiwan area, Turkey and Greece. In order to investigate the characteristics of these sequences along with different temporal and spatial coordinates, each sequence has been divided into dozens of segments called "sub-sequences". The ETAS (Epidemic Type Aftershock Sequences) model is applied to each "sub-sequence", and therefore the vectors of parameters of ETAS could be evaluated. Another model named LR (Logistic Regression) model is used to seek the correlate relation between the parameters of ETAS applied to every earthquake "sub-sequence" and seismicity. All the analyses and estimations imply that the characteristic of decay of aftershock sequences in different temporal and spatial domains seems to be characterized by the parameters of the ETAS model applied to some aftershock sequences or "sub-sequences", and there are some proportional correlate relations between the evaluation of LR model and the occurrence probability of the succeeding strong seismic energy release. [ABSTRACT FROM AUTHOR]

We present an application of hidden Markov models (HMMs) to analysis of geodetic time series in Southern California. Our model-fitting method uses a regularized version of the deterministic annealing expectation-maximization algorithm to ensure that model solutions are both robust and of high quality. Using the fitted models, we segment the daily displacement time series collected by 127 stations of the Southern California Integrated Geodetic Network (SCIGN) over a two-year period. Segmentations of the series are based on statistical changes as identified by the trained HMMs. We look for correlations in state changes across multiple stations that indicate region-wide activity. We find that although in one case a strong seismic event was associated with a spike in station correlations, in all other cases in the study, time period strong correlations were not associated with any seismic event. This indicates that the method was able to identify more subtle signals associated with aseismic events or long-range interactions between smaller events. [ABSTRACT FROM AUTHOR]

A simplified model for anisotropic mantle convection based on a novel class of rheologies, originally developed for folding instabilities in multilayered rock (Mühlhaus et al., 2002), is extended through the introduction of a thermal anisotropy dependent on the local layering. To examine the effect of the thermal anisotropy on the evolution of mantle material, a parallel implementation of this model was undertaken using the Escript modelling toolkit and the Finley finite-element computational kernel (Davies et al., 2004). For the cases studied, there appears too little if any effect. For comparative purposes, the effects of anisotropic shear viscosity and the introduced thermal anisotropy are also presented. These results contribute to the characterization of viscous anisotropic mantle convection subject to variation in thermal conductivities and shear viscosities. [ABSTRACT FROM AUTHOR]

Scientific visualization is an ingredient essential to understanding the large amounts of data generated from large-scale numerical simulations, laboratory experiments and geological surveys. Visualization forms an integral component of any complete framework, together with services to handle mathematical and statistical analysis, storage, feature extraction, and other functions. To support rapid and seamless collaborations and communication between researchers across geographically disparate regions necessitates a distributed infrastructure that supports redundancy, fault tolerance, and most importantly, ease of use. We describe herein an architecture based on Naradabrokering, a publish/subscribe framework that supports the above requirements. We have implemented an initial version of this architecture and describe some initial experiments. [ABSTRACT FROM AUTHOR]

Visualizing and analyzing datasets in the geosciences is becoming increasingly complicated as their volumes are growing explosively. This poses a challenging problem for researchers who must sift through terabytes of data to discover useful relationships inside the information. There is a great need for geophysicists to interactively explore their data sets. Conventional visualization systems lack adequate bandwidth and rendering capabilities necessary for the largest data sets. CAVE and Powerwall display devices are necessary for researchers to explore their data sets in an immersive setting. We describe a utilitarian system targeted specifically at the cost-effective interactive exploration of data sets tens of terabytes in size and harness this system for visualization and analysis of geophysical simulations. Webcams can be used as a steering device to track a local region of interest, which is useful for remote visualization of large data sets. This system will be employed as a web-service under the auspices of Narada-Brokering, while using webcam technologies to enable remote visualization for collaborating researchers. Webcams can be incorporated in a point-to-point network for rapid exchange of information and quickly announcing natural disasters, such as tsunamis, landslides and earthquakes. [ABSTRACT FROM AUTHOR]

Pattern Informatics (PI) technique can be used to detect precursory seismic activation or quiescence and make an earthquake forecast. Here we apply the PI method for optimal forecasting of large earthquakes in Japan, using the data catalogue maintained by the Japan Meteorological Agency. The PI method is tested to forecast large (magnitude m ≥ 5) earthquakes spanning the time period 1995-2004 in the Kobe region. Visual inspection and statistical testing show that the optimized PI method has forecasting skill, relative to the seismic intensity data often used as a standard null hypothesis. Moreover, we find in a retrospective forecast that the 1995 Kobe earthquake (m = 7.2) falls in a seismically anomalous area. Another approach to test the forecasting algorithm is to create a future potential map for large (m ≥ 5) earthquake events. This is illustrated using the Kobe and Tokyo regions for the forecast period 2000-2009. Based on the resulting Kobe map we point out several forecasted areas: The epicentral area of the 1995 Kobe earthquake, the Wakayama area, the Mie area, and the Aichi area. The Tokyo forecast map was created prior to the occurrence of the Oct. 23, 2004 Niigata earthquake (m = 6.8) and the principal aftershocks with 5.0 ≤ m. We find that these events were close to in a forecasted area on the Tokyo map. The PI technique for regional seismicity observation substantiates an example showing considerable promise as an intermediate-term earthquake forecasting in Japan. [ABSTRACT FROM AUTHOR]

A series of acoustic emission (AE) experiments of rock failure have been conducted under cyclic load in tri-axial stress tests. To simulate the hypocenter condition the specimens are loaded by the combined action of a constant stress, intended to simulate the tectonic loading, and a small sinusoidal disturbance stress, analogous to the Earth tide induced by the Sun and the Moon. Each acoustic emission signal can indicate the occurrence time, location and relative magnitude of the damage (micro-crack) in the specimen. The experimental results verified some precursors such as LURR (Load/Unload Response Ratio) and AER (Accelerating Energy Release) before macro-fracture of the samples. A new parameter, the correlation between the AE and the load, has been proposed to describe the loading history. On the eve of some strong earthquakes the correlation between the Benioff strain and the Coulomb failure stress (CFS) decreases, similar to the variation of LURR prior to strong earth quakes. [ABSTRACT FROM AUTHOR]

The Load/Unload Response Ratio (LURR) method is a proposed technique to predict earthquakes that was first put forward by (1987). LURR is based on the idea that when an area enters the damage regime, the rate of seismic activity during loading of the tidal cycle increases relative to the rate of seismic activity during unloading in the months to one year preceding a large earthquake. Since earth tides generally contribute the largest temporal variations in crustal stress, it seems plausible that earth tides would trigger earthquakes in areas that are close to failure (e.g., Vidale et al., 1998). However, the vast majority of studies have shown that earth tides do not trigger earthquakes (e.g., Vidale et al., 1998; Heaton, 1982; Rydelek et al., 1992). In this study, we conduct an independent test of the LURR method, since there would be important scientific and social implications if it were proven to be a robust method of earthquake prediction. (2004) undertook a similar study and found no evidence that there was predictive significance to the LURR method. We have repeated calculations of LURR for the Northridge earthquake in California, following both the parameters of X. C. Yin (personal communication) and the somewhat different ones of (2004). Though we have followed both sets of parameters closely, we have been unable to reproduce either set of results. Our examinations have shown that the LURR method is very sensitive to certain parameters. Thus it seems likely that the discrepancies between our results and those of previous studies are due to unaccounted for differences in the calculation parameters. A general agreement was made at the 2004 ACES Workshop in China between research groups studying LURR to work cooperatively to resolve the differences in methods and results, and thus permit more definitive conclusions on the potential usefulness of the LURR method in earthquake prediction. [ABSTRACT FROM AUTHOR]

After reviewing the problems associated with the current implementation of the LURR theory, we suggest that taking account of stress field complexity and stress reorientation may resolve these problems. By introducing the concept of Maximum Faulting Orientation (MFO), we propose a new approach for calculating LURR. Results presented for the case of the Northridge earthquake provide encouragement for the stress-reorientation explanation and the new approach. [ABSTRACT FROM AUTHOR]

In terms of the spatial scanning of LURR (Load-Unload Response Ratio), we have been predicting the seismic tendency within the next year for the mainland of China from 1995 to 2003. In order to make the quantitative retrospective assessment of LURR method, we compare the results with Poisson null hypothesis. The results show that the prediction by LURR method is much better than Poisson hypothesis. [ABSTRACT FROM AUTHOR]

The spatial and temporal variation of LURR (Load/Unload Respond Ratio) in California during April 2002 to June 2004 was studied in this paper. The result shows that before the San Simeon earthquake (35.7 N, 121.1 W) on Dec. 22, 2003, Y/Yc anomalous region occurred successively near the epicenter from April 2002 to June 2002, and the maximum anomaly of Y/Yc occurred in May, 2002. The published research work pointed out that the Y/Yc anomaly near the San Simeon earthquake appeared from March, 2002. Compared with the five earthquake cases out of the six with M≥6.5 in California during the period from 1980 to 2001, the maximum Y/Yc and duration of Y/Yc anomaly before this earthquake are among the normal ranges, but the time delay from the maximum anomaly time to the occurrence time of this earthquake is the longest one. The result also shows that two areas with Y/Yc anomalies occurred from Oct. 2002 and Dec. 2002, respectively. According to statistical characteristics of the relationship between Y/Yc anomalies and the coming earthquakes, the seismic tendency in California was discussed in this paper. [ABSTRACT FROM AUTHOR]

The 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 finite-element based software tool, which is built on our longterm and ongoing effort to develop the R-minimum strategy based finite-element computational algorithm and software tool for modelling three-dimensional nonlinear frictional contact behavior between multiple deformable bodies with the arbitrarily-shaped 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. [ABSTRACT FROM AUTHOR]

We describe the goals and initial implementation of the International Solid Earth Virtual Observatory (iSERVO). This system is built using a Web Services approach to Grid computing infrastructure and is accessed via a component-based Web portal user interface. We describe our implementations of services used by this system, including Geographical Information System (GIS)-based data grid services for accessing remote data repositories and job management services for controlling multiple execution steps. iSERVO is an example of a larger trend to build globally scalable scientific computing infrastructures using the Service Oriented Architecture approach. Adoption of this approach raises a number of research challenges in millisecond-latency message systems suitable for internet-enabled scientific applications. We review our research in these areas. [ABSTRACT FROM AUTHOR]

We are developing simulation and analysis tools in order to develop a solid Earth Science framework for understanding and studying active tectonic and earthquake processes. The goal of QuakeSim and its extension, the Solid Earth Research Virtual Observatory (SERVO), is to study the physics of earthquakes using state-of-the-art modeling, data manipulation, and pattern recognition technologies. We are developing clearly defined accessible data formats and code protocols as inputs to simulations, which are adapted to high-performance computers. The solid Earth system is extremely complex and nonlinear, resulting in computationally intensive problems with millions of unknowns. With these tools it will be possible to construct the more complex models and simulations necessary to develop hazard assessment systems critical for reducing future losses from major earthquakes. We are using Web (Grid) service technology to demonstrate the assimilation of multiple distributed data sources (a typical data grid problem) into a major parallel high-performance computing earthquake forecasting code. Such a linkage of Geoinformatics with Geocomplexity demonstrates the value of the Solid Earth Research Virtual Observatory (SERVO) Grid concept, and advances Grid technology by building the first real-time large-scale data assimilation grid. [ABSTRACT FROM AUTHOR]

Large earthquakes are catastrophic natural disasters which can potentially cause massive casulaties and huge property loss. In the beginning of the new century, large earthquakes violently struck the world, especially in the Asia-Pacific region. Nearly 300,000 people were killed by the magnitude 9.0 Northern Sumatra Earthquake and tsunami, and the magnitude 7.8 Pakistan earthquake of October 8th, 2005, which resulted in 90,000 deaths. In the meantime, there has been great progress in computational earthquake physics. New understanding of earthquake processes, numerous ideas on earthquake dynamics and complexity, next-generation numerical models and methods, higher performance supercomputers, and new data and analysis methods are emerging. These include the SERVO gird and iSERVO, LSM (Lattice Solid particle simulation Model); Australian Computational Earth Systems Simulator (ACcESS); Japan's Earth Simulator; GeoFEM; GeoFEST; QuakeSim; LURR (Load-Unload Response Ratio); earthquake Critical Point Hypothesis, PI (Pattern Informatics), Critical Sensitivity, friction laws and seismicity, episodic tremor, the Virtual California model, interaction between faults and the interactions between earthquakes, ROC (Receiver Operating Characteristic), SMDM (Statistical Mesoscopic Damage Mechanics) and MFEM (Multi-scale Finite-Element Model), among others. [ABSTRACT FROM AUTHOR]