Site-specific Probabilistic Seismic Hazard Map of Himachal Pradesh, India. Part I. Site-specific Ground Motion Relations

The inputs to probabilistic seismic hazard studies (seismic source zones, earthquake rates, attenuation functions, etc.) are uncertain, being based on subjective judgments and interpretations of limited data. In the face of this uncertainty, we consider (a) how one might “reasonably” determine the ground-motion levels to show on a single probabilistic seismic hazard map, and (b) the extent to which uncertainty in the calculated levels can be meaningfully represented on such a map. If the “best guess” estimates of the earthquake rate, the Gutenberg-Richter b-value and the maximum magnitude for a single source zone are regarded as uncorrelated and the uncertainty in each parameter can be regarded as symmetric about the estimated value, then the probabilistic ground-motion levels calculated using these best estimates represent both most likely values and also approximate mean values.

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Deaggregation of Probabilistic Seismic Hazard and Construction of Pseudo-Exact Conditional Spectrum for China

10.21203/rs.3.rs-567089/v1 ◽

2021 ◽

Author(s):

Kun Ji ◽

Ruizhi Wen ◽

Yefei Ren ◽

Weiyi Wang ◽

Lansheng Chen

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Geometric Mean ◽

Mainland China ◽

National Standard ◽

Probabilistic Seismic Hazard ◽

Hazard Map ◽

Fifth Generation ◽

Ground Motion Parameter ◽

Seismic Hazard Map

Abstract For mainland China, the primary obstacle in conditional spectrum (CS) based ground motion selection work is that the corresponding seismic hazard deaggregation results were not released for the China national standard GB 18306- 2015 “Seismic Ground Motion Parameter Zonation Map”, which refers to the fifth-generation seismic hazard map. Therefore, this study firstly constructed a probabilistic seismic hazard map for mainland China using the three level seismicity source models as applied to produce the fifth-generation seismic hazard map. The derived peak ground acceleration (PGA) values in our seismic hazard map were basically consistent with the fifth-generation seismic hazard map for most of the 34 principal Chinese cities considered. Then, three-dimensional deaggregation scheme was performed for PGA and 5%-damped spectral acceleration (Sa) corresponding to mean return periods of 475 and 2475 years. Based on the magnitude-longitude-latitude deaggregation results of three example cities: Xichang, Kunming, and Xi’an, approximate and pseudo-exact conditional spectrum were established with/without considering multiple casual earthquakes and possible strike directions of the potential source areas. The mean pseudo-exact CS lies between the results of approximate CS using long and short axis GMMs. The conditional standard deviation of pseudo-exact CS is approximately 1.1 to 1.5 times larger than the approximate CS for the periods away from the conditional period. For three example cities, hazard consistency of the spectral accelerations of the ground motion realizations matching target distribution of pseudo-exact CS and geometric mean approximate CS were evaluated and validated. Moreover, for the 34 studied cities, we tabulated the uniform hazard curve and deaggregation results for PGA and Sa values (0.2, 0.3, 0.5, 0.7, 1.0, 1.5, and 2.0s) at MRPs of 475 and 2475 years. (https://github.com/JIKUN1990/China-Seismic-Hazard-Deaggregation-34cities)

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Probabilistic seismic hazard maps for California do not perform better relative to historical shaking data when site-specific VS30 is considered

10.5194/egusphere-egu21-6633 ◽

2021 ◽

Author(s):

Molly Gallahue ◽

Leah Salditch ◽

Madeleine Lucas ◽

James Neely ◽

Susan Hough ◽

...

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Tall Buildings ◽

Historical Period ◽

Probabilistic Seismic Hazard ◽

Hazard Maps ◽

Site Specific ◽

Seismic Hazard Maps ◽

Intensity Mapping ◽

Aleatory Variability

<div> <p>Probabilistic seismic hazard assessments forecast levels of earthquake shaking that should be exceeded with only a certain probability over a given period of time are important for earthquake hazard mitigation. These rely on assumptions about when and where earthquakes will occur, their size, and the resulting shaking as a function of distance as described by ground-motion models (GMMs) that cover broad geologic regions. Seismic hazard maps are used to develop building codes.</p> </div><div> <p>To explore the robustness of maps&#8217; shaking forecasts, we consider how maps hindcast past shaking. We have compiled the California Historical Intensity Mapping Project (CHIMP) dataset of the maximum observed seismic intensity of shaking from the largest Californian earthquakes over the past 162 years. Previous comparisons between the maps for a constant V<sub>S30</sub> (shear-wave velcoity in the top 30 m of soil) of 760 m/s and CHIMP based on several metrics suggested that current maps overpredict shaking.</p> <p>The differences between the V<sub>S30</sub> at the CHIMP sites and the reference value of 760 m/s could amplify or deamplify the ground motions relative to the mapped values. We evaluate whether the V<sub>S30 </sub>at the CHIMP sites could cause a possible bias in the models.&#160;By comparison with the intensity data in CHIMP, we find that using site-specific V<sub>S30</sub> does not improve map performance, because the site corrections cause only minor differences from the original 2018 USGS hazard maps at the short periods (high frequencies) relevant to peak ground acceleration and hence MMI. The minimal differences reflect the fact that the nonlinear deamplification due to increased soil damping largely offsets the linear amplification due to low V<sub>S30</sub>. The net effects will be larger for longer periods relevant to tall buildings, where net amplification occurs.&#160;</p> <div> <p>Possible reasons for this discrepancy include&#160;limitations of the dataset, a bias in the hazard models, an over-estimation of the aleatory variability of the ground motion or that seismicity throughout the historical period has been lower than the long-term average, perhaps by chance due to the variability of earthquake recurrence. Resolving this discrepancy, which is also observed in Italy and Japan, could improve the performance of seismic hazard maps and thus earthquake safety for California and, by extension, worldwide. We also explore whether new nonergodic GMMs, with reduced aleatory variability, perform better than presently used ergodic GMMs compared to historical data.</p> </div> </div>

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Earthquake-Induced Landslide Risk Assessment: An Example from Sakhalin Island, Russia

Geosciences ◽

10.3390/geosciences9070305 ◽

2019 ◽

Vol 9 (7) ◽

pp. 305 ◽

Cited By ~ 3

Author(s):

Alexey Konovalov ◽

Yuriy Gensiorovskiy ◽

Valentina Lobkina ◽

Alexandra Muzychenko ◽

Yuliya Stepnova ◽

...

Keyword(s):

Risk Assessment ◽

Seismic Hazard ◽

Ground Motion ◽

Sakhalin Island ◽

Landslide Risk ◽

Hazard Map ◽

Probabilistic Technique ◽

Landslide Risk Assessment ◽

Seismic Hazard Map ◽

The Given

Damages caused by earthquake-induced ground effects can be of the order or significantly exceed the expected damages from ground shaking. A new probabilistic technique is considered in this study for earthquake-induced landslide risk assessment. A fully probabilistic technique suggests a multi-stage hazard assessment. These stages include the determination of seismic hazard curves and landslide probabilistic models, a vulnerability assessment, and geotechnical investigations. At each of the stages, the uncertainties should be carefully analyzed. A logic tree technique, which handles all available models and parameters, was used in the study. The method was applied considering child education facilities located at the foot of a natural slope in the south of Sakhalin Island which is known as an active seismic and land sliding area. The significant differences in the ground motion scenario in terms of the 475-year seismic hazard map and the fully probabilistic approach considered suggests that seismic landslide risk could be underestimated or overestimated when using the 475-year seismic hazard map for risk assessment. The given approach follows the rational risk management idea that handles well all possible ground motion scenarios, slope models, and parameters. The authors suggest that the given approach can improve geotechnical studies of slope stability.

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The study and revision of the probabilistic seismic hazard map and dam safety code of Taiwan

New Generation Design Codes for Geotechnical Engineering Practice — Taipei 2006 ◽

10.1142/9789812772480_0012 ◽

2006 ◽

Author(s):

Chin-Tung Cheng ◽

Shian-Jin Chiou ◽

Chyi-Tyi Lee ◽

Po-Shen Lin ◽

Yi-Ben Tsai

Keyword(s):

Seismic Hazard ◽

Probabilistic Seismic Hazard ◽

Dam Safety ◽

Hazard Map ◽

Safety Code ◽

Seismic Hazard Map

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A probabilistic seismic hazard map for the metropolitan France

Bulletin of Earthquake Engineering ◽

10.1007/s10518-020-00790-7 ◽

2020 ◽

Vol 18 (5) ◽

pp. 1865-1898 ◽

Cited By ~ 3

Author(s):

Stéphane Drouet ◽

Gabriele Ameri ◽

Kristell Le Dortz ◽

Ramon Secanell ◽

Gloria Senfaute

Keyword(s):

Seismic Hazard ◽

Probabilistic Seismic Hazard ◽

Hazard Map ◽

Seismic Hazard Map

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From Ergodic to Region- and Site-Specific Probabilistic Seismic Hazard Assessment: Method Development and Application at European and Middle Eastern Sites

Earthquake Spectra ◽

10.1193/081016eqs130m ◽

2017 ◽

Vol 33 (4) ◽

pp. 1433-1453 ◽

Cited By ~ 19

Author(s):

Sreeram Reddy Kotha ◽

Dino Bindi ◽

Fabrice Cotton

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Hazard Assessment ◽

Method Development ◽

Site Response ◽

Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard ◽

Site Specific ◽

Aleatory Variability

The increasing numbers of recordings at individual sites allows quantification of empirical linear site-response adjustment factors ( δS2 S s) from the ground motion prediction equation (GMPE) residuals. The δS2 S s are then used to linearly scale the ergodic GMPE predictions to obtain site-specific ground motion predictions in a partially non-ergodic Probabilistic Seismic Hazard Assessment (PSHA). To address key statistical and conceptual issues in the current practice, we introduce a novel empirical region- and site-specific PSHA methodology wherein, (1) site-to-site variability ( φ S2 S) is first estimated as a random-variance in a mixed-effects GMPE regression, (2) δS2 S s at new sites with strong motion are estimated using the a priori φ S2 S, and (3) the GMPE site-specific single-site aleatory variability σ ss,s is replaced with a generic site-corrected aleatory variability σ0. Comparison of region- and site-specific hazard curves from our method against the traditional ergodic estimates at 225 sites in Europe and Middle East shows an approximate 50% difference in predicted ground motions over a range of hazard levels—a strong motivation to increase seismological monitoring of critical facilities and enrich regional ground motion data sets.

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Probabilistic Seismic Hazard Analysis and Synthetic Ground Motion Generation for Seismic Risk Assessment of Structures in the Northeast India

International Journal of Geotechnical Earthquake Engineering ◽

10.4018/ijgee.2017070103 ◽

2017 ◽

Vol 8 (2) ◽

pp. 39-59 ◽

Cited By ~ 4

Author(s):

Swarup Ghosh ◽

Subrata Chakraborty

Keyword(s):

Risk Assessment ◽

Seismic Hazard ◽

Ground Motion ◽

Seismic Risk ◽

Hazard Analysis ◽

Probabilistic Seismic Hazard Analysis ◽

Seismic Hazard Analysis ◽

Probabilistic Seismic Hazard ◽

Seismic Risk Assessment ◽

Site Specific

This article outlines the performance-based seismic risk assessment (PBSRA) of structures requiring probabilistic seismic hazard analysis (PSHA) to obtain hazard curves and an evaluation of the demand model by a nonlinear structural response analysis under properly selected ground motion records. Unfortunately, such site-specific information is not readily available for Northeast region of India. The present study focuses on these two aspects to supplement the PBSRA. The estimations of hazard curves are demonstrated by considering the seismicity within 300 km radius around the considered locations and specified exposure period. Due to limited availability of natural records in this region, synthetic accelerograms are generated using stochastic point source models by identifying the most contributing magnitude distance combinations from disaggregation of the PSHA results. The significant variabilities observed in the estimated hazard, synthetic accelerograms and nonlinear building responses in the various locations indicate the need of explicit site-specific analysis for PBRSA of structures in the region.

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