Probabilistic seismic hazard assessment and site analyses of Arusha International Conference Centre (AICC), Arusha, Tanzania

This work presents the evaluation of earthquake resistance of the Arusha International ConferenceCentre (AICC) complex, in Tanzania. The evaluation included probabilistic seismic hazardanalysis (PSHA) and site response analysis. Seismic sources considered to constitute a seismichazard in this study were randomly occurring seismicity located within five tectonic provincesaround the site. For each province the seismic hazard is based on a cursory analysis of earthquakedata from compiled ESARSWG bulletins and temporary deployed networks within the NorthTanzania Divergence (NTD). Bedrock response signal together with the information of materialcharacteristics from boreholes around the AICC site were used in analysis of site response. PSHAresults indicated uniform hazard spectra values of 0.15, 0.2 and 0.27 g for return periods of 475,975 and 2475 years, respectively. The surface ground response results indicated a maximumamplification factor of 3.7 and a spectral response of 4.5 g for a wave period of 0.6 sec thatmatches the natural frequency of the 6-7 storey buildings of the AICC complex. It is thisresonance effect on the buildings that is assumed to have caused intense shaking in the earthquakeof December 5th 2005 from Lake Tanganyika. Keywords: Probabilistic seismic hazard analysis; Arusha International Conference Centre; EastAfrican Rift System; Uniform hazard spectra; Site effect.

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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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A review on the multi-criteria seismic hazard analysis of Ethiopia: with implications of infrastructural development

Geoenvironmental Disasters ◽

10.1186/s40677-020-00175-7 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Alemayehu Ayele ◽

Kifle Woldearegay ◽

Matebie Meten

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Active Fault ◽

Site Response ◽

Seismic Hazard Assessment ◽

Earthquake Ground Motion ◽

Response Analysis ◽

Ethiopian Rift ◽

Rift System ◽

Main Ethiopian Rift

AbstractEarthquake is a sudden release of energy due to faults. Natural calamities like earthquakes can neither be predicted nor prevented. However, the severity of the damages can be minimized by development of proper infrastructure which includes microzonation studies, appropriate construction procedures and earthquake resistant designs. The earthquake damaging effect depends on the source, path and site conditions. The earthquake ground motion is affected by topography (slope, hill, valley, canyon, ridge and basin effects), groundwater and surface hydrology. The seismic hazard damages are ground shaking, structural damage, retaining structure failures and lifeline hazards. The medium to large earthquake magnitude (< 6) reported in Ethiopia are controlled by the main Ethiopian rift System. The spatial and temporal variation of earthquake ground motion should be addressed using the following systematic methodology. The general approaches used to analyze damage of earthquake ground motions are probabilistic seismic hazard assessment (PSHA), deterministic seismic hazard assessment (DSHA) and dynamic site response analysis. PSHA considers all the scenarios of magnitude, distance and site conditions to estimate the intensity of ground motion distribution. Conversely, DSHA taken into account the worst case scenarios or maximum credible earthquake to estimate the intensity of seismic ground motion distribution. Furthermore, to design critical infrastructures, DSHA is more valuable than PSHA. The DSHA and PSHA ground motion distributions are estimated as a function of earthquake magnitude and distance using ground motion prediction equations (GMPEs) at top of the bedrock. Site response analysis performed to estimate the ground motion distributions at ground surface using dynamic properties of the soils such as shear wave velocity, density, modulus reduction, and material damping curves. Seismic hazard evaluation of Ethiopia shown that (i) amplification is occurred in the main Ethiopian Rift due to thick soil, (ii) the probability of earthquake recurrence due to active fault sources. The situation of active fault is oriented in the N-S direction. Ethiopia is involved in huge infrastructural development (including roads, industrial parks and railways), increasing population and agricultural activity in the main Ethiopian Rift system. In this activity, socio-economic development, earthquake and earthquake-generated ground failures need to be given attention in order to reduce losses from seismic hazards and create safe geo-environment.

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Probabilistic Seismic Hazard Assessment for the Shanxi Rift System, North China

Bulletin of the Seismological Society of America ◽

10.1785/0120190099 ◽

2020 ◽

Vol 110 (1) ◽

pp. 127-153

Author(s):

Bin Li ◽

Mathilde Bøttger Sørensen ◽

Kuvvet Atakan ◽

Yanrong Li ◽

Zihong Li

Keyword(s):

Seismic Hazard ◽

Seismic Hazard Assessment ◽

Rift System ◽

Probabilistic Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard ◽

Earthquake Catalog ◽

Local Site Effects ◽

The North ◽

Local Site ◽

Shanxi Rift

ABSTRACT We present the first probabilistic seismic hazard assessment (PSHA) specifically for the Shanxi rift system, north China, which has been defined as one of the areas of highest seismic hazard and risk in China in recent decades. We applied a Monte Carlo-based approach to PSHA, based on so far the most complete earthquake catalog available, a detailed zonation considering both seismicity distribution and local tectonic features, a logic tree of carefully selected ground-motion prediction equations, as well as a cautious consideration of actual local site effects for this region. Both areal sources (for Ms<6.0) and fault sources (for Ms≥6.0) were considered, and a synthetic earthquake catalog was generated through Monte Carlo simulation. A logic tree was applied to represent the epistemic uncertainty related to attenuation models for the rift system. Actual local site effects were incorporated and the stability of the results was also tested in this study. Our results show that nearly the entire rift system faces a significant seismic hazard and associated high seismic risk, as more than 80% of the population and the main economical infrastructure of Shanxi are concentrated here. The highest hazard is found in the areas around the north margin of Tianzhen fault and the north segment of Hengshan fault in the north, and in the Linfen basin and the area around Zhongtiaoshan fault in the south of the rift system. Our results are comparable to, but a refinement of, the results of previous probabilistic seismic hazard studies in the region. Deaggregation of seismic hazard for five large cities in the rift system indicates that the seismic hazard is most contributed by the nearby sources. Results obtained in this study provide a better understanding of the seismic hazard in the Shanxi rift system and can thereby help guiding earthquake risk mitigation in the future.

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