scholarly journals Evaluation of Seismic Hazard Models with Fragile Geologic Features

2020 ◽  
Vol 92 (1) ◽  
pp. 314-324
Author(s):  
Mark W. Stirling ◽  
Michael E. Oskin ◽  
J. Ramon Arrowsmith ◽  
Anna H. Rood ◽  
Christine A. Goulet ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Peak Ground Velocity ◽  
Hazard Models ◽  
Ethical Considerations ◽  
Ground Acceleration ◽  
Research Areas ◽  
Methods Of Evaluation ◽  
Wide Range ◽  
Similar Vein

Abstract We provide an overview of a 2019 workshop on the use of fragile geologic features (FGFs) to evaluate seismic hazard models. FGFs have been scarcely utilized in the evaluation of seismic hazard models, despite nearly 30 yr having passed since the first recognition of their potential value. Recently, several studies have begun to focus on the implementation of FGFs in seismic hazard modeling. The workshop was held to capture a “snapshot” of the state-of-the-art in FGF work and to define key research areas that would increase confidence in FGF-based evaluation of seismic hazard models. It was held at the annual meeting of the Southern California Earthquake Center on 8 September 2019, and the conveners were Mark Stirling (University of Otago, New Zealand) and Michael Oskin (University of California, Davis). The workshop attracted 44 participants from a wide range of disciplines. The main topics of discussion were FGF fragility age estimation (age at which an FGF achieved its current fragile geometry), fragility estimation, FGF-based evaluation of seismic hazard models, and ethical considerations relating to documentation and preservation of FGFs. There are now many scientists working on, or motivated to work on, FGFs, and more types of FGFs are being worked on than just the precariously balanced rock (PBR) variety. One of the ideas presented at the workshop is that fragility ages for FGFs should be treated stochastically rather than assuming that all share a common age. In a similar vein, new studies propose more comprehensive methods of fragility assessment beyond peak ground acceleration and peak ground velocity-based approaches. Two recent studies that apply PBRs to evaluate probabilistic seismic hazard models use significantly different methods of evaluation. Key research needs identified from the workshop will guide future, focused efforts that will ultimately facilitate the uptake of FGFs in seismic hazard analysis.

scholarly journals Seismic Hazard Assessment for the Tianshui Urban Area, Gansu Province, China

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenming Wang ◽  
David T. Butler ◽  
Edward W. Woolery ◽  
Lanmin Wang
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Design ◽  
Hazard Analysis ◽  
Seismic Hazard Assessment ◽  
Gansu Province ◽  
Mitigation Measures ◽  
Peak Ground Velocity ◽  
Ground Acceleration ◽  
Acceleration Time Histories

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui.

scholarly journals Vector-Valued Fragility Analysis Using PGA and PGV Simultaneously as Ground-Motion Intensity Measures

2010 ◽  
Vol 5 (4) ◽  
pp. 407-416
Author(s):  
Sei’ichiro Fukushima ◽  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Fragility Curves ◽  
Fragility Analysis ◽  
Peak Ground Velocity ◽  
Seismic Risk Analysis ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Vector Valued

Seismic risk analysis usually expresses ground-motion intensity using a single index such as peak ground acceleration (PGA), spectral acceleration for a specified period, or peak ground velocity (PGV). Limiting the number of indices, however, adds greater uncertainty when estimating annual failure probability given by convolving seismic hazard and fragility curves. This is because information other than ground-motion intensity is missing. Author proposed seismic hazard analysis using PGA and PGV simultaneously as groundmotion input measures. After analyzing the correlation coefficient between PGA and PGV using K-NET and KiK-net databases, probabilistic seismic hazard for seven sites in Kanto district in Japan was evaluated. In this study, seismic fragility analysis using PGA and PGV is conducted followed by advantage of vector-valued fragility analysis.

Estimation of Peak Ground Acceleration and Its Uncertainty for Northern Indian Region

2011 ◽  
Vol 2 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Girish Chandra Joshi ◽  
Mukat Lal Sharma
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Seismic Hazard Assessment ◽  
Indian Region ◽  
Branch Points ◽  
Logic Tree ◽  
Ground Acceleration ◽  
Source Models ◽  
Hazard Parameters

In the present study the authors evaluate uncertainties in the seismic hazard assessment for the Northern Indian region, based on the probabilistic seismic hazard analysis (PSHA). The newly compiled earthquake data has been treated for the quality, consistency, and homogeneity in a systematic manner to find out the uncertainties in every step of calculations. Based on the geological and tectonic setup, seismicity and other geophysical anomalies, a seismotectonic model of the region has been developed. The seismic hazard parameters are calculated based on giving proper weight to specific region. The peak ground acceleration (PGA) is estimated for various return periods for the Northern Indian region using a logic tree approach. The variation at the input level in terms of the source models and different Ground Motion Prediction Equations (GMPEs) is used. To examine into the effect of source modelling and GMPEs, the Coefficient of Variation (COV) maps have been generated. To encompass the region and for better resolution, the peak ground acceleration (PGA) is estimated at 15 minute intervals. The COV values due to all branch points in the logic tree decrease with distance from the source and conspicuous increase toward fault boundaries are observed.

scholarly journals Peak ground acceleration at surface for Mataram city with a return period of 2500 years using probabilistic method

2018 ◽  
Vol 195 ◽  
pp. 03019
Author(s):  
Rian Mahendra Taruna ◽  
Vrieslend Haris Banyunegoro ◽  
Gatut Daniarsyad
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
Peak Ground Acceleration ◽  
Subduction Zones ◽  
Amplification Factor ◽  
Hazard Analysis ◽  
Probabilistic Method ◽  
Seismic Zone ◽  
Ground Acceleration ◽  
Back Arc

The Lombok region especially Mataram city, is situated in a very active seismic zone because of the existence of subduction zones and the Flores back arc thrust. Hence, the peak ground acceleration (PGA) at the surface is necessary for seismic design regulation referring to SNI 1726:2012. In this research we conduct a probabilistic seismic hazard analysis to estimate the PGA at the bedrock with a 2% probability of exceedance in 50 years corresponding to the return period of 2500 years. These results are then multiplied by the amplification factor referred from shear wave velocity at 30 m depth (Vs30) and the microtremor method. The result of the analysis may describe the seismic hazard in Mataram city which is important for building codes.

Seismic Hazard Estimation in East China Offshore Areas

2013 ◽  
Vol 690-693 ◽  
pp. 1158-1167
Author(s):  
Li Fang Zhang ◽  
Yan Ju Peng ◽  
Zhen Ming Wang
Keyword(s):  
Seismic Hazard ◽  
Seismic Activity ◽  
Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
East China ◽  
Earthquake Catalog ◽  
Ground Acceleration ◽  
Study Region ◽  
Seismicity Model ◽  
Seismic Hazard Estimation

In this study, we chose East China offshore areas as study region(N25°~41°，E117°~126°).According to the tectonic environments and characteristics of earthquake the seismotectonic units were established, taking Gaussian spatially smoothing only based on the input earthquake catalog, and fault-rupture-oriented elliptical smoothing to calculate the seismic activity rate in each cells. The maps for the distribution of horizontal peak ground acceleration with 10% probability of exceedance in 50 years were obtained through using the method of seismic hazard analysis based on cell source. While the total number of earthquakes unchanged, two-stage smoothing procedure deals with the error of epicenter location, contains the seismotectonic information in elliptical smoothing seismicity model. This method build up a simple and easy methodology of probabilistic seismic hazard analysis, especially for those place where not yet been clearly master the seismic tectonic information and with distributed Seismic activity.

scholarly journals Estimation of peak ground acceleration and spectral acceleration for South India with local site effects: probabilistic approach

2009 ◽  
Vol 9 (3) ◽  
pp. 865-878 ◽  
Author(s):  
K. S. Vipin ◽  
P. Anbazhagan ◽  
T. G. Sitharam
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
South India ◽  
Hazard Analysis ◽  
Shear Zones ◽  
Spectral Acceleration ◽  
Ground Acceleration ◽  
Site Class ◽  
Probability Of Exceedance ◽  
Grid Points

Abstract. In this work an attempt has been made to evaluate the seismic hazard of South India (8.0° N–20° N; 72° E–88° E) based on the probabilistic seismic hazard analysis (PSHA). The earthquake data obtained from different sources were declustered to remove the dependent events. A total of 598 earthquakes of moment magnitude 4 and above were obtained from the study area after declustering, and were considered for further hazard analysis. The seismotectonic map of the study area was prepared by considering the faults, lineaments and the shear zones in the study area which are associated with earthquakes of magnitude 4 and above. For assessing the seismic hazard, the study area was divided into small grids of size 0.1°×0.1°, and the hazard parameters were calculated at the centre of each of these grid cells by considering all the seismic sources with in a radius of 300 km. Rock level peak horizontal acceleration (PHA) and spectral acceleration (SA) values at 1 s corresponding to 10% and 2% probability of exceedance in 50 years have been calculated for all the grid points. The contour maps showing the spatial variation of these values are presented here. Uniform hazard response spectrum (UHRS) at rock level for 5% damping and 10% and 2% probability of exceedance in 50 years were also developed for all the grid points. The peak ground acceleration (PGA) at surface level was calculated for the entire South India for four different site classes. These values can be used to find the PGA values at any site in South India based on site class at that location. Thus, this method can be viewed as a simplified method to evaluate the PGA values at any site in the study area.

Seismic Hazard Analysis for an NPP Site

2004 ◽  
Author(s):  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Structural Response ◽  
Response Spectra ◽  
Seismic Fragility ◽  
Material Strength ◽  
Ground Acceleration ◽  
Hazard Response

The various uncertainties and randomness associated with the occurrence of earthquakes and the consequences of their effects on the NPP components and structures call for a probabilistic seismic risk assessment (PSRA). However, traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to be computed for PGA only. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for Kakrapar Atomic Power Station site. Sensitivity of the results to the changes in various parameters has also been presented. These results determine the seismic hazard at the given site and the associated uncertainties. The paper also presents some results of the seismic fragility for an existing containment structure. The various parameters that could affect the seismic structural response include material strength of concrete, structural damping available within the structure and the normalized ground motion response spectral shape. Based on this limited case study the seismic fragility of the structure is developed. The results are presented as families of conditional probability curves plotted against the peak ground acceleration (PGA). The procedure adopted incorporates the various randomness and uncertainty associated with the parameters under consideration.

scholarly journals Uncertainties in attenuation relations for New Zealand seismic hazard analysis

1986 ◽  
Vol 19 (1) ◽  
pp. 28-39 ◽  
Author(s):  
G. H. McVerry
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Seismic Hazard Analysis ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Ground Shaking ◽  
Acceleration Data

Probabilistic techniques for seismic hazard analysis have
come into vogue in New Zealand for both the assessment of major projects and the development and review of seismic design codes. However, there are considerable uncertainties in the modelling
 of the strong-motion attenuation, which is necessarily based largely on overseas data. An excellent agreement is obtained between an average 5% damped response spectrum for New Zealand alluvial sites in the 20 to 59 km distance range and 5.4 to 6.0 magnitude class and that given by a Japanese model. Unfortunately, this corresponds to only about half the amplitude levels of 150 year spectra relevant to code design. The much more rapid decay
of ground shaking with distance in New Zealand has led to a considerable modification based on maximum ground acceleration
data from the Inangahua earthquake of the distance-dependence
of the Japanese response spectra model. Less scatter in New Zealand data has resulted in adopting a lower standard deviation for the attenuation model, which is important in reducing the considerable "probabilistic enhancement" of the hazard estimates. Regional differences in attenuation shown by intensities are difficult to resolve from the strong-motion acceleration data, apart from lower accelerations in Fiordland.

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