Uncertainties in probabilistic seismic hazard assessment as a function of probability level: A case history for Vancouver, British Columbia

abstract The stability of probabilistic methods of evaluating expected strong ground motion levels is examined as a function of probability level. A case history for Vancouver, British Columbia, is used to show that when input parameters are screened on the basis of compatibility with low probability calculations, robust (±25 per cent) results are obtained for probabilities in the range of 10−2 to 10−4 per annum. There is no inherent loss of stability with decreasing probability. Probabilistic approaches are not in conflict with deterministic approaches, since deterministic data can be incorporated into the analysis. The usefulness of the probabilistic approach lies in providing a framework for evaluating uncertainties.

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Probabilistic Seismic Hazard Assessment of Sudan and Its Vicinity

Earthquake Spectra ◽

10.1193/1.1586181 ◽

2001 ◽

Vol 17 (3) ◽

pp. 399-415 ◽

Cited By ~ 8

Author(s):

Jamal A. Abdalla ◽

Yahia E-A. Mohamedzein ◽

A. Abdel Wahab

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Seismic Activity ◽

Probabilistic Approach ◽

Seismic Hazard Assessment ◽

Seismic Source ◽

Probabilistic Seismic Hazard Assessment ◽

Seismic Zone ◽

Ground Acceleration ◽

Grid Points

This paper presents seismic hazard assessment and seismic zoning of Sudan and its vicinity based on probabilistic approach. The area studied lies between 22° E- 45° E and 0° - 24° N. Tectonics of Sudan and its vicinity is first reviewed. An updated NOAA catalogue, containing both historical and instrumental events and covering the period from 700 A.D. to 1993 is then used. Seismic source regions are modeled and relationships between earthquake magnitude and earthquake frequency are established. A modified attenuation relation is used. Seismic hazard assessment is then carried out for 60 km interval grid points. Seismic hazard maps of the studied area based on peak ground acceleration (PGA) for 10% probability of exceedance for time-spans of 50, 100, 200 and 250 years are presented. The results showed that the PGA ranges from 0.02g for low seismic activity regions to around 0.62g for high seismic activity regions. A seismic zone map is also shown for 475 years return period.

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A probabilistic seismic hazard assessment for Greece and the surrounding region including site-specific considerations

Annals of Geophysics ◽

10.4401/ag-3367 ◽

2009 ◽

Vol 47 (6) ◽

Author(s):

T. M. Tsapanos ◽

P. Mäntyniemi ◽

A. Kijko

Keyword(s):

Seismic Hazard ◽

Probabilistic Approach ◽

Region Of Interest ◽

Seismic Hazard Assessment ◽

Soil Conditions ◽

Probabilistic Seismic Hazard Assessment ◽

Time Interval ◽

Ground Acceleration ◽

Design Earthquake ◽

Seismic Hazard Map

A probabilistic approach was applied to map the seismic hazard in Greece and the surrounding region. The procedure does not require any specification of seismic sources or/and seismic zones and allows for the use of the whole seismological record, comprising both historical and instrumental data, available for the region of interest. The new seismic hazard map prepared for Greece and its vicinity specifies a 10% probability of exceedance of the given Peak Ground Acceleration (PGA) values for shallow seismicity and intermediate soil conditions for an exposure time of 50 years. When preparing the map, the new PGA attenuation relation given by Margaris et al. (2001) was employed. The new map shows a spatial distribution of the seismic hazard that corresponds well with the features of shallow seismicity within the examined region. It depicts the level of seismic hazard in which the exceedance of the PGA value of 0.25 g may be expected to occur within limited areas. The highest estimated levels of seismic hazard inside the territory of Greece are found in the Northern Sporades Islands, where PGA values in excess of 0.50 g are reached at individual sites, and in the Zante Island in Western Greece, where PGA values in the range of 0.35 g to 0.40 g are obtained at more numerous localities. High values are also observed in the sea between the Karpathos and Rhodes islands, near the Island of Amorgos (Cyclades Archipelago) and in the Southwestern Peloponnesus. The levels of seismic hazard at the sites of seven Greek cities (Athens, Jannena, Kalamata, Kozani, Larisa, Rhodes and Thessaloniki) were also estimated in terms of probabilities that a given PGA value will be exceeded at least once during a time interval of 1, 50 and 100 years at those sites. These probabilities were based on the maximum horizontal PGA values obtained by applying the design earthquake procedure, and the respective median values obtained were 0.24 g for Athens, 0.28 g for Jannena, 0.30 g for Kalamata, 0.21 g for Kozani, 0.24 g for Larisa, 0.43 g for Rhodes and 0.35 g for Thessaloniki. The probabilities of exceedance of the estimated maximum possible PGA value were also calculated for the cities to illustrate the uncertainty of maximum PGA assessment.

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Probabilistic Seismic Hazard Assessment of the Kermanshah-Sanandaj Region of Western Iran

Earthquake Spectra ◽

10.1193/1.2431210 ◽

2007 ◽

Vol 23 (1) ◽

pp. 175-197 ◽

Cited By ~ 12

Author(s):

Elham Shabani ◽

Noorbakhsh Mirzaei

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Eleventh Century ◽

Probabilistic Approach ◽

Seismic Hazard Assessment ◽

Earthquake Hazard ◽

Probabilistic Seismic Hazard Assessment ◽

Return Periods ◽

Ground Acceleration ◽

Western Iran

Seismic hazard assessment and zoning of the Kermanshah-Sanandaj region in western Iran is conducted using probabilistic approach. Two maps have been prepared to indicate the earthquake hazard of the region in the form of iso-acceleration contour lines. They display a probabilistic estimate of peak ground acceleration (PGA) over bedrock for the return periods of 475 and 50 years. A uniform catalog of earthquakes containing historical and instrumental events covering the period from the eleventh century A.D. to 2003 is used. Twelve potential seismic sources are modeled as area sources in the region. Seismicity parameters are evaluated using the method in which magnitude uncertainty and incompleteness of earthquake data are considered. Seismic hazard assessment is carried out for a grid of 357 points with 0.1° intervals using the SEISRISKIII computer program for the study area encompassed by the 46–48° E longitudes and 34–36° N latitudes. This region includes the most active segments of the Zagros Main Recent Fault; among them, the Sahneh and Nahavand faults have a well-known history of intense seismic activity. PGA values for this region are estimated to be 0.35 g and 0.20 g for 475- and 50-years return periods, respectively.

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Accounting for Uncertainties in the Safety Assessment of Concrete Gravity Dams: A Probabilistic Approach with Sample Optimization

Water ◽

10.3390/w13060855 ◽

2021 ◽

Vol 13 (6) ◽

pp. 855

Author(s):

Rocio L. Segura ◽

Benjamin Miquel ◽

Patrick Paultre ◽

Jamie E. Padgett

Keyword(s):

Probabilistic Approach ◽

Sampling Strategy ◽

Design Guidelines ◽

Probabilistic Methods ◽

Computationally Efficient ◽

Promising Alternative ◽

Concrete Gravity Dams ◽

Dam Stability ◽

The Stability ◽

Parameter Ranges

Important advances have been made in the methodologies for assessing the safety of dams, resulting in the review and modification of design guidelines. Many existing dams fail to meet these revised criteria, and structural rehabilitation to achieve the updated standards may be costly and difficult. To this end, probabilistic methods have emerged as a promising alternative and constitute the basis of more adequate procedures of design and assessment. However, such methods, in addition to being computationally expensive, can produce very different solutions, depending on the input parameters, which can greatly influence the final results. Addressing the existing challenges of these procedures to analyze the stability of concrete dams, this study proposes a probabilistic-based methodology for assessing the safety of dams under usual, unusual, and extreme loading conditions. The proposed procedure allows the analysis to be updated while avoiding unnecessary simulation runs by classifying the load cases according to the annual probability of exceedance and by using an efficient progressive sampling strategy. In addition, a variance-based global sensitivity analysis is performed to identify the parameters most affecting the dam stability, and the parameter ranges that meet the safety guidelines are formulated. It is observed that the proposed methodology is more robust, more computationally efficient, and more easily interpretable than conventional methods.

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Evaluating variability in coseismic slips of paleoearthquakes from an incomplete slip history: an example from displaced terrace flights across the Kamishiro fault, central Japan

Progress in Earth and Planetary Science ◽

10.1186/s40645-021-00407-w ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Naoya Takahashi ◽

Shinji Toda

Keyword(s):

Monte Carlo ◽

Three Dimensional ◽

Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard Assessment ◽

Reverse Fault ◽

Central Japan ◽

Systematic Analysis ◽

Fluvial Terraces ◽

Rupture Length ◽

Slip History

AbstractExamining the regularity in slip over seismic cycles leads to an understanding of earthquake recurrence and provides the basis for probabilistic seismic hazard assessment. Systematic analysis of three-dimensional paleoseismic trenches and analysis of offset markers along faults reveal slip history. Flights of displaced terraces have also been used to study slips of paleoearthquakes when the number of earthquakes contributing to the observed displacement of a terrace is known. This study presents a Monte Carlo-based approach to estimating slip variability using displaced terraces when a detailed paleoseismic record is not available. First, we mapped fluvial terraces across the Kamishiro fault, which is an intra-plate reverse fault in central Japan, and systematically measured the cumulative dip slip of the mapped terraces. By combining these measurements with the age of the paleoearthquakes, we estimated the amount of dip slip for the penultimate event (PE) and antepenultimate event (APE) to be 1.6 and 3.4 m, respectively. The APE slip was nearly three times larger than the most recent event of 2014 (Mw 6.2): 1.2 m. This suggests that the rupture length of the APE was much longer than that of the 2014 event and the entire Kamishiro fault ruptured with adjacent faults during the APE. Thereafter, we performed the Monte Carlo simulations to explore the possible range of the coefficient of variation for slip per event (COVs). The simulation considered all the possible rupture histories in terms of the number of events and their slip amounts. The resulting COVs typically ranged between 0.3 and 0.54, indicating a large variation in the slip per event of the Kamishiro fault during the last few thousand years. To test the accuracy of our approach, we performed the same simulation to a fault whose slip per event was well constrained. The result showed that the error in the COVs estimate was less than 0.15 in 86% of realizations, which was comparable to the uncertainty in COVs derived from a paleoseismic trenching. Based on the accuracy test, we conclude that the Monte Carlo-based approach should help assess the regularity of earthquakes using an incomplete paleoseismic record.

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Probabilistic seismic hazard assessment for two potential nuclear power plant sites in Tunisia

Arabian Journal of Geosciences ◽

10.1007/s12517-021-06536-2 ◽

2021 ◽

Vol 14 (3) ◽

Author(s):

Emna Jarraya ◽

Sami Montassar ◽

Othman Ben Mekki ◽

Hassene Hamdi

Keyword(s):

Power Plant ◽

Nuclear Power Plant ◽

Seismic Hazard ◽

Hazard Assessment ◽

Nuclear Power ◽

Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard

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The performance of ultra-lightweight foamed concrete incorporating nanosilica

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00234-2 ◽

2021 ◽

Vol 21 (2) ◽

Author(s):

Mohamed Abd Elrahman ◽

Pawel Sikora ◽

Sang-Yeop Chung ◽

Dietmar Stephan

Keyword(s):

Wall Thickness ◽

Probabilistic Approach ◽

Drying Shrinkage ◽

Dry Density ◽

Optimal Dosage ◽

X Ray ◽

Mechanical And Physical Properties ◽

Fresh State ◽

Foamed Concrete ◽

The Stability

AbstractThis paper aims to investigate the feasibility of the incorporation of nanosilica (NS) in ultra-lightweight foamed concrete (ULFC), with an oven-dry density of 350 kg/m3, in regard to its fresh and hardened characteristics. The performance of various dosages of NS, up to 10 wt.-%, were examined. In addition, fly ash and silica fume were used as cement replacing materials, to compare their influence on the properties of foamed concrete. Mechanical and physical properties, drying shrinkage and the sorption of concrete were measured. Scanning electron microscopy (SEM) and X-ray microcomputed tomography (µ-CT) and a probabilistic approach were implemented to evaluate the microstructural changes associated with the incorporation of different additives, such as wall thickness and pore anisotropy of produced ULFCs. The experimental results confirmed that the use of NS in optimal dosage is an effective way to improve the stability of foam bubbles in the fresh state. Incorporation of NS decrease the pore anisotropy and allows to produce a foamed concrete with increased wall thickness. As a result more robust and homogenous microstructure is produced which translate to improved mechanical and transport related properties. It was found that replacement of cement with 5 wt.-% and 10 wt.-% NS increase the compressive strength of ULFC by 20% and 25%, respectively, when compared to control concrete. The drying shrinkage of the NS-incorporated mixes was higher than in the control mix at early ages, while decreasing at 28 d. In overall, it was found that NS is more effective than other conventional fine materials in improving the stability of fresh mixture as well as enhancing the strength of foamed concrete and reducing its porosity and sorption.

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