Influence of local site effects on seismic risk maps and ranking of Italian municipalities

Fabio Sabetta; Gabriele Fiorentino; Flavio Bocchi; Martina Sinibaldi; Gaetano Falcone; Amerigo Mendicelli

doi:10.1007/s10518-023-01619-9

Influence of local site effects on seismic risk maps and ranking of Italian municipalities

Fabio Sabetta
, Gabriele Fiorentino^*
, Flavio Bocchi
, Martina Sinibaldi
, Gaetano Falcone
, Amerigo Mendicelli

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

20 Citations (Scopus)

Abstract

The latest studies concerning seismic risk assessment in Italy were developed without considering the site geo-lithological effects, thus limiting the assessment to rock soil type. In this study, for the evaluation of site amplification effects, we used the results of recent works based on the Italian seismic microzonation data. As this first study is performed for the entire Italian territory at the municipality scale, the site amplification factors (AFs) have been assigned to the chief town of each of the 7715 Italian municipalities, assuming that the building stock is concentrated in that small area. The AFs have been compared with those foreseen by the Italian building code (NTC2018). The PGA amplification with the new AFs ranges from 1 to 2.2 bringing to an average increase of 75% in the hazard, compared to 27% if using the NTC2018 amplification. The seismic risk has been evaluated using the probabilistic hazard assessment adopted in the NTC2018 and recent vulnerability/exposure models developed for Italy. The residential building stock was subdivided into 5 vulnerability classes (3 for masonry and 2 for concrete) derived from the national census data and further refined using the construction age and building height. The results show that, for a rock site condition, the loss estimates are comparable with those of previous works in terms of casualties, homeless, and economic damage. The introduction of the site effects brings to a significant increase in the expected losses resulting higher than the historical data retrieved from a careful analysis of the major Italian earthquakes. This suggests the importance of developing new fragility curves based on updated AFs. To support the implementation of risk reduction programs, a seismic risk index is introduced, allowing a municipality ranking by risk, a cost estimation of the seismic retrofitting in the highest risk municipalities, and an assessment of the consequent risk reduction.

Original language	English
Pages (from-to)	2441-2468
Number of pages	28
Journal	Bulletin of Earthquake Engineering
Volume	21
Issue number	5
DOIs	https://doi.org/10.1007/s10518-023-01619-9
Publication status	Published - 3 Feb 2023

Bibliographical note

Funding Information:
European Union’s Horizon 2020 research program under the Marie Curie Grant Agreement No. 892454 ( https://cordis.europa.eu/project/id/892454/it ).

Funding Information:
The authors would like to thank Annalisa Rosti, Andrea Penna, Maria Rota and Gianmarco De Felice for the fruitful discussions that definitely help to improve the quality of the paper. The authors thank the anonymous reviewers for their insightful comments and suggestions. Gabriele Fiorentino has received funding from the European Union’s Horizon 2020 research program under the Marie Curie Grant Agreement No. 892454 ( https://cordis.europa.eu/project/id/892454/it ).

Publisher Copyright:
© 2023, The Author(s).

Keywords

Fragility curves
Loss assessment
Risk reduction programs
Seismic hazard
Seismic risk
Site effects

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title = "Influence of local site effects on seismic risk maps and ranking of Italian municipalities",

abstract = "The latest studies concerning seismic risk assessment in Italy were developed without considering the site geo-lithological effects, thus limiting the assessment to rock soil type. In this study, for the evaluation of site amplification effects, we used the results of recent works based on the Italian seismic microzonation data. As this first study is performed for the entire Italian territory at the municipality scale, the site amplification factors (AFs) have been assigned to the chief town of each of the 7715 Italian municipalities, assuming that the building stock is concentrated in that small area. The AFs have been compared with those foreseen by the Italian building code (NTC2018). The PGA amplification with the new AFs ranges from 1 to 2.2 bringing to an average increase of 75\% in the hazard, compared to 27\% if using the NTC2018 amplification. The seismic risk has been evaluated using the probabilistic hazard assessment adopted in the NTC2018 and recent vulnerability/exposure models developed for Italy. The residential building stock was subdivided into 5 vulnerability classes (3 for masonry and 2 for concrete) derived from the national census data and further refined using the construction age and building height. The results show that, for a rock site condition, the loss estimates are comparable with those of previous works in terms of casualties, homeless, and economic damage. The introduction of the site effects brings to a significant increase in the expected losses resulting higher than the historical data retrieved from a careful analysis of the major Italian earthquakes. This suggests the importance of developing new fragility curves based on updated AFs. To support the implementation of risk reduction programs, a seismic risk index is introduced, allowing a municipality ranking by risk, a cost estimation of the seismic retrofitting in the highest risk municipalities, and an assessment of the consequent risk reduction.",

keywords = "Fragility curves, Loss assessment, Risk reduction programs, Seismic hazard, Seismic risk, Site effects",

author = "Fabio Sabetta and Gabriele Fiorentino and Flavio Bocchi and Martina Sinibaldi and Gaetano Falcone and Amerigo Mendicelli",

note = "Funding Information: European Union{\textquoteright}s Horizon 2020 research program under the Marie Curie Grant Agreement No. 892454 ( https://cordis.europa.eu/project/id/892454/it ). Funding Information: The authors would like to thank Annalisa Rosti, Andrea Penna, Maria Rota and Gianmarco De Felice for the fruitful discussions that definitely help to improve the quality of the paper. The authors thank the anonymous reviewers for their insightful comments and suggestions. Gabriele Fiorentino has received funding from the European Union{\textquoteright}s Horizon 2020 research program under the Marie Curie Grant Agreement No. 892454 ( https://cordis.europa.eu/project/id/892454/it ). Publisher Copyright: {\textcopyright} 2023, The Author(s).",

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AU - Bocchi, Flavio

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AU - Falcone, Gaetano

AU - Mendicelli, Amerigo

N1 - Funding Information: European Union’s Horizon 2020 research program under the Marie Curie Grant Agreement No. 892454 ( https://cordis.europa.eu/project/id/892454/it ). Funding Information: The authors would like to thank Annalisa Rosti, Andrea Penna, Maria Rota and Gianmarco De Felice for the fruitful discussions that definitely help to improve the quality of the paper. The authors thank the anonymous reviewers for their insightful comments and suggestions. Gabriele Fiorentino has received funding from the European Union’s Horizon 2020 research program under the Marie Curie Grant Agreement No. 892454 ( https://cordis.europa.eu/project/id/892454/it ). Publisher Copyright: © 2023, The Author(s).

PY - 2023/2/3

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N2 - The latest studies concerning seismic risk assessment in Italy were developed without considering the site geo-lithological effects, thus limiting the assessment to rock soil type. In this study, for the evaluation of site amplification effects, we used the results of recent works based on the Italian seismic microzonation data. As this first study is performed for the entire Italian territory at the municipality scale, the site amplification factors (AFs) have been assigned to the chief town of each of the 7715 Italian municipalities, assuming that the building stock is concentrated in that small area. The AFs have been compared with those foreseen by the Italian building code (NTC2018). The PGA amplification with the new AFs ranges from 1 to 2.2 bringing to an average increase of 75% in the hazard, compared to 27% if using the NTC2018 amplification. The seismic risk has been evaluated using the probabilistic hazard assessment adopted in the NTC2018 and recent vulnerability/exposure models developed for Italy. The residential building stock was subdivided into 5 vulnerability classes (3 for masonry and 2 for concrete) derived from the national census data and further refined using the construction age and building height. The results show that, for a rock site condition, the loss estimates are comparable with those of previous works in terms of casualties, homeless, and economic damage. The introduction of the site effects brings to a significant increase in the expected losses resulting higher than the historical data retrieved from a careful analysis of the major Italian earthquakes. This suggests the importance of developing new fragility curves based on updated AFs. To support the implementation of risk reduction programs, a seismic risk index is introduced, allowing a municipality ranking by risk, a cost estimation of the seismic retrofitting in the highest risk municipalities, and an assessment of the consequent risk reduction.

AB - The latest studies concerning seismic risk assessment in Italy were developed without considering the site geo-lithological effects, thus limiting the assessment to rock soil type. In this study, for the evaluation of site amplification effects, we used the results of recent works based on the Italian seismic microzonation data. As this first study is performed for the entire Italian territory at the municipality scale, the site amplification factors (AFs) have been assigned to the chief town of each of the 7715 Italian municipalities, assuming that the building stock is concentrated in that small area. The AFs have been compared with those foreseen by the Italian building code (NTC2018). The PGA amplification with the new AFs ranges from 1 to 2.2 bringing to an average increase of 75% in the hazard, compared to 27% if using the NTC2018 amplification. The seismic risk has been evaluated using the probabilistic hazard assessment adopted in the NTC2018 and recent vulnerability/exposure models developed for Italy. The residential building stock was subdivided into 5 vulnerability classes (3 for masonry and 2 for concrete) derived from the national census data and further refined using the construction age and building height. The results show that, for a rock site condition, the loss estimates are comparable with those of previous works in terms of casualties, homeless, and economic damage. The introduction of the site effects brings to a significant increase in the expected losses resulting higher than the historical data retrieved from a careful analysis of the major Italian earthquakes. This suggests the importance of developing new fragility curves based on updated AFs. To support the implementation of risk reduction programs, a seismic risk index is introduced, allowing a municipality ranking by risk, a cost estimation of the seismic retrofitting in the highest risk municipalities, and an assessment of the consequent risk reduction.

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KW - Loss assessment

KW - Risk reduction programs

KW - Seismic hazard

KW - Seismic risk

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SP - 2441

EP - 2468

JO - Bulletin of Earthquake Engineering

JF - Bulletin of Earthquake Engineering

IS - 5

ER -

Influence of local site effects on seismic risk maps and ranking of Italian municipalities

Abstract

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Keywords

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