A probabilistic seismic hazard model for North Africa

Poggi, Valerio; Garcia-Pelaez, Julio Antonio; Styron, Richard; Pagani, Marco; Gee, Robin

doi:10.1007/s10518-020-00820-4

Cited by 27 publications

(21 citation statements)

References 82 publications

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“…It can also be observed that with a single source zone, the variation in PGA is low as compared to multi-source in this study. This is supported by the results obtained by Poggi et al (2016) who characterized NTD into three zones and obtained PGA values ranging from 80-320 cm/s/s, which are comparable to the results of this study. In addition, the PGA values of 150 cm/s/s and 120 cm/s/s for cities of Arusha and Dodoma, respectively located within the rift, compared well with the results reported by Lubkowski et al (2014).…”

Section: Resultssupporting

confidence: 92%

Probabilistic seismic hazard analysis for Northern Tanzania Divergence Region and the adjoining areas

Msabi

Ferdinand

2021

Tanz. J. Sci.

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This paper presents the seismic hazard levels for the Northern Tanzania Divergence (NTD) and adjoining areas by using area seismic source zones. The 15 source zones were considered based on the major geological and tectonic features, faulting style, and seismicity trends. For each source, earthquake recurrence parameters were computed by using the earthquake catalogue with events compiled from 1956 to 2011. The peak ground accelerations (PGA) and spectral accelerations (SA) at 0.2 and 2.0 second, respectively, were computed for a 10% probability of exceedance in 50 years at sites defined by a 0.1° x 0.1° grid. The recurrence parameters of 15 zones and attenuation relations developed by Akkar et al. (2014) and Chiou and Youngs (2014) were integrated in a logic tree. Obtained results that are presented as hazard maps show strong spatial variations ranging from 60 to 330 cm/s/s for PGA, from 100 to 650 cm/s/s at 0.2 sec and from 6 to 27 cm/s/s at 2 sec for 475 years mean return period and 5% damping. Hazard levels depict the general tectonic setting of the study area with the western (Eyasi-Wembere) and central (Natron-Manyara-Balangida) rift segments having relatively high PGA values compared with the eastern Pangani rift. This work provides indications of seismic hazards to policymakers and planners during planning and guidelines for earthquake-resistant design engineers. Keywords: Homogeneous Earthquakes Catalogue; GMPE; PSHA; NTD

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Section: Resultssupporting

confidence: 92%

Probabilistic seismic hazard analysis for Northern Tanzania Divergence Region and the adjoining areas

Msabi

Ferdinand

2021

Tanz. J. Sci.

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“…As shown in previous studies (Hofmann 1996;Wesnousky et al 1983) and implemented in other urban (Ebrahimian et al 2019) and regional (Danciu et al 2017;Poggi et al 2020) hazard analysis studies, modeling a unique MFD relationship for the faults for all magnitude ranges (small, moderate and large) may result in an increase of small to moderate earthquakes compared to the observations. A common practice to alleviate this problem is to use fault modeling only for the larger magnitude earthquakes and to use a background seismicity model for small to moderate events.…”

Section: Faults and Background Seismicity Source Modelingmentioning

confidence: 72%

“…To account for the spatial variability of the seismicity, as described in Poggi et al (2020), we use a smoothed seismicity approach (Frankel 1995) to redistribute the annual occurrence rates within each polygon (i.e., Z1-Z7) considering the spatial density of earthquakes using an isotropic seismicity smoothing kernel. This approach allows using zone speci c b GR and seismic modeling parameters such as rupture mechanism, depth distribution and M max .…”

Section: Nomentioning

confidence: 99%

“…We then classi ed these seven zones into the three tectonic regions of active shallow crust, stable continental and deep seismicity regions. To e ciently account for the spatial distribution of the events within the distributed seismicity model, we considered a smoothing occurrence rate redistribution following the recommendations of Poggi et al (2020). For each seismotectonic region, we selected a group of most recent ground motion prediction equations (GMPEs) to quantify the ground motion intensity on rock and soil conditions.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

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Site specific probabilistic seismic hazard model for Isfahan, Iran: estimates and uncertainties

Kohrangi

Safaei

Danciu

et al. 2022

Bull Earthquake Eng

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We present a seismic source characterization model for the probabilistic seismic hazard assessment (PSHA) of the Isfahan urban area, Iran. We compiled the required datasets including the earthquake catalogue and the geological and seismotectonic structure and faults systems within the study region to delineate and characterize seismic source models. We identi ed seven relatively large zones that bound each region with similar seismotectonic characteristics and catalogue completeness periods. These regions were used for calculating the b-value of the Gutenberg-Richter magnitude recurrence relationship and for estimating the maximum magnitude value within each region. The recurrence parameters were then used to build a spatially varying distributed seismic source model using a smoothed kernel. Additionally, based on a fault database developed in this study and on a local expert's opinion about their slip velocity, an active faults based model is also created. We further performed sets of sensitivity analyses to nd stable estimates of the ground motion intensity and to de ne alternative branches for both the seismogenic source and ground motion prediction models. Site ampli cation is considered based on a Vs 30 map for

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“…The model for Northern Africa (Poggi et al, 2020) was built by the GEM Hazard Team using an earthquake catalog covering the entire region and a new database of shallow active faults (Styron and Poggi, 2018) compiled as part of the construction of the GAF-DB. The SSC consists of two SSMs: one which includes both smoothed seismicity and fault sources, and a second containing only smoothed seismicity, but using different smoothing lengths than the former SSM, and considering epistemic uncertainty of seismicity rates.…”

Section: Europe and Africamentioning

confidence: 99%

The 2018 version of the Global Earthquake Model: Hazard component

et al. 2020

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In December 2018, at the conclusion of its second implementation phase, the Global Earthquake Model (GEM) Foundation released its first version of a map outlining the spatial distribution of seismic hazard at a global scale. The map is the result of an extensive, joint effort combining the results obtained from a collection of probabilistic seismic hazard models, called the GEM Mosaic. Together, the map and the underlying database of models provide an up-to-date view of the earthquake threat globally. In addition, using the Mosaic, a synopsis of the current state-of-practice in modeling probabilistic seismic hazard at national and regional scales is possible. The process adopted for the compilation of the Mosaic adhered to the maximum extent possible to GEM’s principles of collaboration, inclusiveness, transparency, and reproducibility. For each region, priority was given to seismic hazard models either developed by well-recognized national agencies or by large collaborative projects involving local scientists. The version of the GEM Mosaic presented herein contains 30 probabilistic seismic hazard models, 14 of which represent national or sub-national models; the remainder are regional-scale models. We discuss the general qualities of these models, the underlying framework of the database, and the outlook for the Mosaic’s utility and its future versions.

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A probabilistic seismic hazard model for North Africa

Cited by 27 publications

References 82 publications

Probabilistic seismic hazard analysis for Northern Tanzania Divergence Region and the adjoining areas

Probabilistic seismic hazard analysis for Northern Tanzania Divergence Region and the adjoining areas

Site specific probabilistic seismic hazard model for Isfahan, Iran: estimates and uncertainties

The 2018 version of the Global Earthquake Model: Hazard component

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