Probabilistic Seismic Hazard Analysis Method Research Articles

A Simple Model for Probabilistic Seismic Hazard Analysis of Induced Seismicity Associated with Deep Geothermal Systems

In the research project MAGS (Microseismic Activity of Geothermal Systems) a simple model was developed to determine seismic hazard as the annual frequency of the exceedance of ground motion of a certain size. Such estimates of the annual frequency of exceedance of prescriptive limits for the effects of vibrations on buildings and people are needed for the planning and licensing, but likewise for the development and operation of deep geothermal systems.For the development of the proposed model well established probabilistic seismic hazard analysis methods for the estimation of the hazard for the case of natural seismicity were adapted to the case of induced seismicity. Important differences between induced and natural seismicity had to be considered. These included significantly smaller magnitudes, depths and source to site distances of the seismic events. Hence, different ground motion prediction equations (GMPE) had to be incorporated to account for the seismic amplitude attenuation with distance, as well as for differences in the stationarity of the underlying tectonic and induced processes. Appropriate GMPEs in terms of peak ground velocity (PGV) were tested and selected from the literature. In the paper we present probabilistic seismic hazard analysis (PSHA) results for ground motion which can be linked to engineering regulations (e.g. German DIN 4150). It is thus possible to specify the probability of exceedance of prescriptive standard values and to decide (e.g. by the regulator responsible for commissioning) whether the annual number of exceedances for a site at a given level is acceptable or not. Additionally, hazard curves for induced and natural seismicity are compared to study the different impact at a site. Preliminary results for the circulation period (operation phase of the plant) at a geothermal site in Bavarian Molasse, Germany - for stiff soil, ignoring site effects - indicate higher frequencies of exceedance for induced seismicity than for natural seismicity only for low PGV values.

Ground Motion Distribution Analysis about Taipei-101 in Earthquake

It is important for tall building to infer seismic hazard analysis. Recently, researchers paid great efforts to study the seismic hazard analysis using the method of probabilistic seismic hazard analysis (PSHA), and PSHA has been proved to be sound and popular. The PSHA method is not new. However, the use of PSHA in China is not extensive. The purpose of this paper is to explore the use of ground motion distribution analysis about one typical tall building Taipei-101. Based on the earthquake catalog around Taiwan with more than 50,000 events over 100-years of recording, the author takes Taipei-101’s geographic coordination as object to do ground motion distribution analysis. The research shows that ground motion is affected significantly by service year, and the chi-square test applied in testing Annual ground motion distribution better than K-S test, In addition, Bernoulli distribution is verified reasonable in evaluating the entire service year ground motion distribution.

Uncertainty Analysis and Expert Judgment in Seismic Hazard Analysis

The large uncertainty associated with the prediction of future earthquakes is usually regarded as the main reason for increased hazard estimates which have resulted from some recent large scale probabilistic seismic hazard analysis studies (e.g. the PEGASOS study in Switzerland and the Yucca Mountain study in the USA). It is frequently overlooked that such increased hazard estimates are characteristic for a single specific method of probabilistic seismic hazard analysis (PSHA): the traditional (Cornell–McGuire) PSHA method which has found its highest level of sophistication in the SSHAC probability method. Based on a review of the SSHAC probability model and its application in the PEGASOS project, it is shown that the surprising results of recent PSHA studies can be explained to a large extent by the uncertainty model used in traditional PSHA, which deviates from the state of the art in mathematics and risk analysis. This uncertainty model, the Ang–Tang uncertainty model, mixes concepts of decision theory with probabilistic hazard assessment methods leading to an overestimation of uncertainty in comparison to empirical evidence. Although expert knowledge can be a valuable source of scientific information, its incorporation into the SSHAC probability method does not resolve the issue of inflating uncertainties in PSHA results. Other, more data driven, PSHA approaches in use in some European countries are less vulnerable to this effect. The most valuable alternative to traditional PSHA is the direct probabilistic scenario-based approach, which is closely linked with emerging neo-deterministic methods based on waveform modelling.

PROBABILISTIC SEISMIC HAZARD ANALYSIS FOR NUCLEAR POWER PLANTS - CURRENT PRACTICE FROM A EUROPEAN PERSPECTIVE

The paper discusses the methodology and the use of probabilistic seismic hazard analysis (PSHA) for nuclear power plants from a European perspective. The increasing importance of risk-informed approaches in the nuclear oversight process observed in many countries has contributed to increasing attention to PSHA methods. Nevertheless significant differences with respect to the methodology of PSHA are observed in Europe. The paper gives an overview on actual projects and discusses the differences in the PSHA-methodology applied in different European countries. These differences are largely related to different approaches used for the treatment of uncertainties and to the use of experts. The development of a probabilistic scenario-based approach is identified as a meaningful alternative to the development of uniform hazard spectra or uniform confidence spectra.

OpenSHA: A Developing Community-modeling Environment for Seismic Hazard Analysis

Probabilistic seismic hazard analysis (PSHA) provides the conceptual framework for estimating the likelihood that something of concern related to earthquake shaking will occur over a specified time period. Based on more than thirty years of research and development ( e.g. , Cornell, 1968; Algermissen et al. , 1982; SSHAC, 1997), PSHA has become a standard tool for combining information on earthquake occurrence, seismic radiation, and shaking response to produce hazard estimates, including the U.S. Geological Survey's national seismic hazard maps (Frankel et al. , 1996, 1997). PSHA methods, while now mature, continue to evolve as scientists improve the characterization of earthquake hazards and engineers develop new measures of seismic shaking for performance-based design. The Southern California Earthquake Center (SCEC), in collaboration with USGS, the California Geological Survey (CGS), and other partners, has undertaken a series of studies aimed at improving the regional application of PSHA methods. Phase I examined the implications of the 1992 Landers earthquake sequence for regional seismic hazards (WGCEP, 1992), Phase II developed a probabilistic earthquake forecast model (WGCEP, 1995), and Phase III assessed the wave-propagation and site effects that give rise to local variations in seismic shaking (see Field et al. [2000] for an overview). The Phase III study found that accounting for some site attributes ( i.e. , the 30-meter shear-wave velocity and basin depth) can lead to significant improvements in PSHA. It was also found that making such corrections does not significantly reduce the prediction uncertainty associated with empirical ground-motion relations. In fact, 3D waveform modeling presented in the same report (Olsen, 2000) implied that this residual uncertainty represents an intrinsic variability caused by complex propagation effects that are unique to each earthquake-rupture/site combination. The Phase III study therefore concluded that significant improvements in PSHA will require replacing the standard empirical-regression …

Uncertainties in Seismic Hazard Maps for the New Madrid Seismic Zone and Implications for Seismic Hazard Communication

Earthquake risk assessment has been described as “a game of chance of which we still don't know all the rules” (Lomnitz, 1989). This challenge is illustrated by attempts to estimate the seismic hazard for parts of the central U.S. due to earthquakes in the New Madrid Seismic Zone (NMSZ). The U.S. Geological Survey National Seismic Hazard Maps predict that the seismic hazard in the area is surprisingly high, in some ways exceeding that in California. These predictions reflect crucial parameter assumptions, many of which have considerable uncertainty due to the absence of instrumental data from any but small earthquakes. Hence we explore the coupled questions of how the predicted hazard depends on various assumptions and how the uncertainties in estimates of hazard might be communicated to scientists, engineers, policy-makers, and others facing the challenge of deciding on seismic safety strategies that balance costs and benefits. At present, most seismic hazard assessment is done using the probabilistic seismic hazard analysis (PSHA) approach developed by Cornell (1968) and widely applied in engineering design ( e.g., Reiter, 1990; McGuire, 1995). An informative and entertaining overview of PSHA is given by Hanks and Cornell (1994). Major studies of seismic hazard in the central and eastern United States, including the NMSZ, were conducted in the 1980's by Lawrence Livermore National Laboratory (Bernreuter et al., 1985) and the Electric Power Research Institute (EPRI, 1986) for application to nuclear power plant licensing. A detailed study of the NMSZ was also carried out for the U.S. Department of Energy for the Gaseous Diffusion Plant in Paducah, Kentucky (Risk Engineering, 1999). Based on these and related efforts, and motivated bythe design and licensing needs of critical facilities, detailed consensus recommendations have been developed for conducting PSHA (SSHAC, 1997). It has become common to apply the PSHA method to …