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  • 1
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    Adaptive Daily Forecasting of Seismic Aftershock Hazard (2014)
    Seismological Society of America (SSA)
    Details
    Publication Date: 2014-02-04
    Description: Seismic aftershock-hazard analysis is one of the first steps toward establishing an integrated risk-based decision-making support framework for emergency management in the event of an ongoing aftershock sequence. This work focuses on providing adaptive daily forecasts of the mean daily rate of exceeding various spectral acceleration values (the aftershock hazard). Two well-established earthquake-occurrence models suitable for daily seismicity forecasts associated with the evolution of an aftershock sequence, namely, the modified Omori’s aftershock model (MO) and the epidemic-type aftershock sequence (ETAS) are adopted. An adaptive and evolutionary MO-based aftershock occurrence model with distinct spatial and temporal components is proposed. In this model, the parameters deciding the temporal decay are updated based on the data provided by the ongoing aftershock sequence. This model adopts an evolutionary spatial seismicity pattern loosely based on spatial clustering of aftershock events in the sequence. Bayesian updating is also employed to provide sequence-based parameter estimates for a given ground-motion prediction model. Daily forecasts of the mean rate of exceedance of various spectral acceleration levels are calculated based on alternative occurrence models and the updated ground-motion prediction relation. As a numerical example, daily forecasts of the aftershock-hazard curve are obtained for the L’Aquila aftershock sequence based on the MO-based and ETAS occurrence models, and an updated version of the Sabetta and Pugliese (1996) ground-motion prediction model. These daily hazard forecasts are then compared with the observed daily rates of exceeding various spectral acceleration thresholds.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America (SSA)
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  • 2
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    Adaptive daily forecasting of seismic aftershock hazard (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-06-22
    Description: Seismic aftershock-hazard analysis is one of the first steps toward estab- lishing an integrated risk-based decision-making support framework for emergency management in the event of an ongoing aftershock sequence. This work focuses on providing adaptive daily forecasts of the mean daily rate of exceeding various spectral acceleration values (the aftershock hazard). Two well-established earthquake- occurrence models suitable for daily seismicity forecasts associated with the evolution of an aftershock sequence, namely, the modified Omori’s aftershock model (MO) and the epidemic-type aftershock sequence (ETAS) are adopted. An adaptive and evolution- ary MO-based aftershock occurrence model with distinct spatial and temporal compo- nents is proposed. In this model, the parameters deciding the temporal decay are updated based on the data provided by the ongoing aftershock sequence. This model adopts an evolutionary spatial seismicity pattern loosely based on spatial clustering of aftershock events in the sequence. Bayesian updating is also employed to provide sequence-based parameter estimates for a given ground-motion prediction model. Daily forecasts of the mean rate of exceedance of various spectral acceleration levels are calculated based on alternative occurrence models and the updated ground-motion prediction relation. As a numerical example, daily forecasts of the aftershock-hazard curve are obtained for the L’Aquila aftershock sequence based on the MO-based and ETAS occurrence models, and an updated version of the Sabetta and Pugliese (1996) ground-motion prediction model. These daily hazard forecasts are then compared with the observed daily rates of exceeding various spectral acceleration thresholds.
    Description: Published
    Description: 145 – 161
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: earthquake forecast ; aftershock ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    A performance-based framework for adaptive seismic aftershock risk assessment (2015)
    Wiley-Blackwell
    Details
    Publication Date: 2021-06-22
    Description: Operative seismic aftershock risk forecasting can be particularly useful for rapid decision-making in the presence of an ongoing sequence. In such a context, limit state first-excursion probabilities (risk) for the forecasting interval (a day) can represent the potential for progressive state of damage in a structure. This work lays out a performance-based framework for adaptive aftershock risk assessment in the immediate post-mainshock environment. A time-dependent structural performance variable is adopted in order to measure the cumulative damage in a structure. A set of event-dependent fragility curves as a function of the first-mode spectral acceleration for a prescribed limit state is calculated by employing back-to-back non- linear dynamic analyses. An epidemic-type aftershock sequence model is employed for estimating the spatio-temporal evolution of aftershocks. The event-dependent fragility curves for a given limit state are then integrated together with the probability distribution of aftershock spectral acceleration based on the epidemic-type aftershock sequence aftershock hazard. The daily probability of limit state first-excursion is finally calculated as a weighted combination of the sequence of limit state probabilities conditioned on the num- ber of aftershocks. As a numerical example, daily aftershock risk is calculated for the L’Aquila 2009 aftershock sequence (central Italy). A representative three-story reinforced concrete frame with infill panels, which has cyclic strength and stiffness degradation, is used in order to evaluate the progressive damage. It is observed that the proposed framework leads to a sound forecasting of limit state first-excursion in the structure for two limit states of significant damage and near collapse. Copyright © 2014 John Wiley & Sons, Ltd.
    Description: Published
    Description: 2179–2197
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: aftershock ; time-dependent reliability ; seismic risk ; etas modeling ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Probabilistic Tsunami Hazard and Risk Analysis: A Review of Research Gaps (2021)
    In:  Frontiers in Earth Science
    Details
    Publication Date: 2021-07-30
    Description: Tsunamis are unpredictable and infrequent but potentially large impact natural disasters. To prepare, mitigate and prevent losses from tsunamis, probabilistic hazard and risk analysis methods have been developed and have proved useful. However, large gaps and uncertainties still exist and many steps in the assessment methods lack information, theoretical foundation, or commonly accepted methods. Moreover, applied methods have very different levels of maturity, from already advanced probabilistic tsunami hazard analysis for earthquake sources, to less mature probabilistic risk analysis. In this review we give an overview of the current state of probabilistic tsunami hazard and risk analysis. Identifying research gaps, we offer suggestions for future research directions. An extensive literature list allows for branching into diverse aspects of this scientific approach.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 5
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    Tsunami risk communication and management: Contemporary gaps and challenges (2022)
    In:  International Journal of Disaster Risk Reduction
    Details
    Publication Date: 2022-01-24
    Description: Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 6
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    Improvements to seismicity forecasting based on a Bayesian spatio-temporal ETAS model (2022)
    In:  Scientific Reports
    Details
    Publication Date: 2023-06-12
    Description: The epidemic-type aftershock sequence (ETAS) model provides an effective tool for predicting the spatio-temporal evolution of aftershock clustering in short-term. Based on this model, a fully probabilistic procedure was previously proposed by the first two authors for providing spatio-temporal predictions of aftershock occurrence in a prescribed forecasting time interval. This procedure exploited the versatility of the Bayesian inference to adaptively update the forecasts based on the incoming information provided by the ongoing seismic sequence. In this work, this Bayesian procedure is improved: (1) the likelihood function for the sequence has been modified to properly consider the piecewise stationary integration of the seismicity rate; (2) the spatial integral of seismicity rate over the whole aftershock zone is calculated analytically; (3) background seismicity is explicitly considered within the forecasting procedure; (4) an adaptive Markov Chain Monte Carlo simulation procedure is adopted; (5) leveraging the stochastic sequences generated by the procedure in the forecasting interval, the N-test and the S-test are adopted to verify the forecasts. This framework is demonstrated and verified through retrospective early forecasting of seismicity associated with the 2017–2019 Kermanshah seismic sequence activities in western Iran in two distinct phases following the main events with Mw7.3 and Mw6.3, respectively.
    Type: info:eu-repo/semantics/article
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  • 7
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    Time-dependent seismic hazard analysis for induced seismicity based on a 3D ETAS model (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-07-03
    Description: Induced earthquakes have peculiar characteristics such as relatively shallow depths, small-to-moderate magnitude, correlation with field operations, non-GR recurrence law, and eventually non-homogenous Poisson recurrence time. Thus, when dealing with induced seismicity, the standard Probabilistic Seismic Hazard Analysis (PSHA) has to be modified.This work aims at exploiting the information carried by the ongoing induced seismic sequence in quasi-real time to provide spatio-temporal predictions of ground shaking in a prescribed forecasting interval (in the order of days). First, the workflow adaptively updates the seismicity forecasts based on the incoming information as it becomes available. The clustering of seismic events in volume (3D seismicity) and time is modelled based on an Epidemic Type Aftershock Sequence (ETAS) model. The proposed 3D ETAS model encompasses a decoupled depth-area volumetric probabilistic kernel. The ETAS parameters will be re-calibrated to take into account non-GR long-term temporal boundary conditions in case of induced seismicity.Second, the PSHA is performed using proper ground motion prediction models (GMPE). By combining the time-dependent seismicity rates provided by ETAS model and the mentioned GMPE, PSHA in a prescribed forecasting interval is adopted for calculating the mean rates of exceeding certain ground-shaking levels. The procedure is demonstrated through retrospective hazard forecasting of induced seismicity recorded at the Geysers geothermal field in northern California in the time period of 2011-2015 during fluid injection in the vicinity of Prati 9 and Prati 29 injection wells. This work has been supported by PRIN-2017 MATISSE project No 20177EPPN2, funded by Italian Ministry of Education and Research.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 8
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    Methodologies for the AssessmenT of anthropogenic environmental hazard: Induced Seismicity by Sub-surface geo-resources Exploitation (MATISSE) (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-07-03
    Description: The goal of MATISSE is to develop and implement technologies needed for successfully detecting and quantifying hazards connected with geo-energy operations in the sub-surface, in particular induced seismicity. Anthropogenic earthquakes constitute one of the major environmental impacts associated with geo-resources exploitation. Injection induced events are an undesired dynamic rockmass response to technological processes. Water injection operations taking place during industrial activities such as oil, gas and geothermal exploitation often induce microseismic activity and, under specific circumstances, reactivate existing faults, causing events of considerable size. These industrial activities can also determine air pollution and ground water contamination.Induced seismic hazard is evaluated through the computation and update of ground motion prediction equations, the time-lapse of velocity, attenuation and seismic noise tomography and the computation of pore pressure time variations. All these parameters are correlated with operational activities. A multi-hazard approach aimed at evaluating the adverse effects on environment caused by the sub-surface exploitation of geo-resources is developed.This work has been supported by PRIN-2017 MATISSE project, No 20177EPPN2, funded by Italian Ministry of Education and Research.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 9
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    Propagating uncertainties from tsunami hazard to risk for Coquimbo Bay (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-08-29
    Description: Tsunami hazard and risk analysis are examples of multi-hazard and multi-risk assessments. The procedure for probabilistic tsunami risk analysis (PTRA) involves characterization, quantification, and propagation of uncertainties from sources to the consequences. A forward and modular probabilistic framework for risk assessment, known as the PEER-type approach was originally developed for single-hazard risk assessment. However, given its practical appeal, it has also been adapted to multi-hazard and multi-risk analysis. We focus on the application of this framework for tsunami risk analysis and demonstrate how the uncertainties are going to be propagated from the hazard to the risk level. The advantage of using this approach, compared to fully simulation-based approaches for tsunami risk assessment, is that it can use already-available hazard, fragility, and consequence models. More specifically, the interval of confidence for the hazard curves can be used as a proxy for epistemic uncertainties. The procedure also considers the epistemic uncertainties in the tsunami fragility curves and the consequence functions. We demonstrate how hazard and fragility curves and their confidence intervals, and the loss models (consequence functions) can be integrated to obtain loss curves for certain locations of interest. An application of this procedure is demonstrated for PTRA for Coquimbo Bay in Chile affected by the 2015 Illapel tsunami which was a near-field tsunami generated by a subduction earthquake of 8.3 Mw rupturing a 240 km section of the Nazca–South American plate interface. We consider fragility functions already developed for mixed (masonry and wood) buildings.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 10
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    Application of an adaptive Bayesian spatio-temporal aftershock forecasting workflow on the 2023 southern Turkey seismic Sequence (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-12-11
    Description: A powerful seismic sequence struck the Turkey-Syria border on Feb. 6 with three earthquakes having M〉6.5. At 01:17 UTC, a M7.8 earthquake occurred that was followed 11 minutes later by a M6.7, and around nine hours later by a M7.5. In the first 24 hours, 20 aftershocks with M〉5 and 68 events with M〉4 have been registered. Recently, we have improved and tested a Bayesian simulation-based workflow for spatio-temporal early seismicity forecasting based on ETAS model. It exploited the versatility of the Bayesian inference to adaptively update the forecasts based on the incoming information from the ongoing sequence. This workflow is demonstrated and verified through retrospective early seismicity forecasting of Central Italy 2016 and the 2017-2019 western Iran seismic sequences. We test this workflow to predict the spatial distribution of events and their uncertainties for various forecasting intervals within this seismic sequence. Bayesian updating is first employed to learn the ETAS model parameters conditioned on the registered events (that already took place). Then, plausible sequences of events during the forecasting interval are adaptively generated. To this end, we strive to simulate those plausible sequences by embedding a branching process formulation inside the proposed workflow as an alternative to the piece-wise stationary integration of the conditional rate. The latter could be a new feature to the forecasting workflow, while its efficiency in providing early forecasts is explored during this study. This work has been supported by PRIN-2017 MATISSE project No 20177EPPN2, funded by Italian Ministry of Education and Research.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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