This paper presents the calibration of Omori’s aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock tha...This paper presents the calibration of Omori’s aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock that exceeds a specific magnitude threshold within a time interval after the mainshock. Critical decisions on the post-earthquake safety of structures directly depend on the aftershock hazard estimated using the occurrence model. It is customary to calibrate models in a region-specific manner. These models depend on rate parameters(a, b, c and p) related to the seismicity characteristics of the investigated region. In this study, the available well-recorded aftershock sequences for a set of Mw ≥ 5.9 mainshock events that were observed in Turkey until 2012 are considered to develop the aftershock occurrence model. Mean estimates of the model parameters identified for Turkey are a =-1.90, b = 1.11, c = 0.05 and p = 1.20. Based on the developed model, aftershock likelihoods are computed for a range of different time intervals and mainshock magnitudes. Also, the sensitivity of aftershock probabilities to the model parameters is investigated. Aftershock occurrence probabilities estimated using the model are expected to be useful for post-earthquake safety evaluations in Turkey.展开更多
Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a l...Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations.Additionally,the performance of engineering structures will be deteriorated by the aggressive environments during their service periods,such as chloride attack,concrete carbonation,and wind-induced fatigue.This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds.The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered.Moreover,the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events.The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds.Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect.The contribution of each hazard event on the total structural failure probability varies with time.Thus,neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.展开更多
Background What factors,processes and mechanisms regulate invasive processes and their efects?This is one of the main questions addressed by the ecology of biological invasions.Ligustrum lucidum,a tree species native ...Background What factors,processes and mechanisms regulate invasive processes and their efects?This is one of the main questions addressed by the ecology of biological invasions.Ligustrum lucidum,a tree species native to East Asia,became an aggressive invader of subtropical and temperate forests around the world.We analyzed here the L.lucidum invasion in Uruguayan forests to determine the factors controlling two stages of the invasive process,the establishment,and the dominance.Establishment was assessed by the occurrence,measured in 1525,1×1 kmcells,and dominance by remotely measuring the L.lucidum coverage at the forest canopy in 5554,1×1 km-cells.The occurrence and dominance were modeled using Generalized Linear Models in function of independent environmental and geographic variables.Results Ligustrum lucidum has become established in 13.4%of the Uruguayan forests and has dominated the forest canopy in 1.2%.Our models explained 45%and 35%of the occurrence and dominance spatial variance respectively and detected in both cases strong difusion patterns from the S-SW region to rest of Uruguay.Occurrence increased mainly in function of urban areas,and with the proximity to towns,probably because L.lucidum trees planted in gardens are seed sources,and near railways and highways,that could function as biological corridors.Occurrence also increased in loamy soils and near rivers,suggesting moisture conditions are favorable for establishment.Dominance increased with reduced forest area,in high productive soils and at higher altitudes.Moreover,dominance increased near urban areas,roads,and railways,as well as in highly aforested landscapes,and in loamy and low-rockiness soils.Conclusions The invasion of Uruguayan forests by L.lucidum is in the spread and impact stages,currently in expansion from the invasion focus on the S-SW region,where the oldest urbanizations are settled,towards the rest of the country.The geographic proximity to the invasion focus is currently the main predictor of both L.lucidum establishment and dominance.Additionally,whereas establishment is manly facilitated by human infrastructures improving propagule pressure and dispersion,dominance is enhanced in small or fragmented forest patches,in richnutrient soils,and at higher altitudes,suggesting ecosystem resistance is also operating.展开更多
Introduction:Incorporating information on animal behavior in resource-based predictive modeling(e.g.,occurrence mapping)can elucidate the relationship between process and spatial pattern and depict habitat in terms of...Introduction:Incorporating information on animal behavior in resource-based predictive modeling(e.g.,occurrence mapping)can elucidate the relationship between process and spatial pattern and depict habitat in terms of its structure as well as its function.In this paper,we assigned location data on brood-rearing greater sage-grouse(Centrocercus urophasianus)to either within-patch(encamped)or between-patch(traveling)behavioral modes by estimating a movement-based relative displacement index.Objectives were to estimate and validate spatially explicit models of within-versus between-patch resource selection for application in habitat management and compare these models to a non-behaviorally adjusted model.Results:A single model,the vegetation and water resources model,was most plausible for both the encamped and traveling modes,including the non-behaviorally adjusted model.When encamped,sage-grouse selected for taller shrubs,avoided bare ground,and were closer to mesic areas.Traveling sage-grouse selected for greater litter cover and herbaceous vegetation.Preference for proximity to mesic areas was common to both encamped and traveling modes and to the non-behaviorally adjusted model.The non-behaviorally adjusted map was similar to the encamped model and validated well.However,we observed different selection patterns during traveling that could have been masked had behavioral state not been accounted for.Conclusions:Characterizing habitat that structured between-patch movement broadens our understanding of the habitat needs of brood-rearing sage-grouse,and the combined raster surface offers a reliable habitat management tool that is readily amenable to application by GIS users in efforts to focus sustainable landscape management.展开更多
基金Supported by:Scientific and Technological Research Council of Turkey(TUBITAK)with Grant No.213M454
文摘This paper presents the calibration of Omori’s aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock that exceeds a specific magnitude threshold within a time interval after the mainshock. Critical decisions on the post-earthquake safety of structures directly depend on the aftershock hazard estimated using the occurrence model. It is customary to calibrate models in a region-specific manner. These models depend on rate parameters(a, b, c and p) related to the seismicity characteristics of the investigated region. In this study, the available well-recorded aftershock sequences for a set of Mw ≥ 5.9 mainshock events that were observed in Turkey until 2012 are considered to develop the aftershock occurrence model. Mean estimates of the model parameters identified for Turkey are a =-1.90, b = 1.11, c = 0.05 and p = 1.20. Based on the developed model, aftershock likelihoods are computed for a range of different time intervals and mainshock magnitudes. Also, the sensitivity of aftershock probabilities to the model parameters is investigated. Aftershock occurrence probabilities estimated using the model are expected to be useful for post-earthquake safety evaluations in Turkey.
基金Supported by:Fundamental Research Funds for the Central Universities under Grant No.2021QN1022。
文摘Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations.Additionally,the performance of engineering structures will be deteriorated by the aggressive environments during their service periods,such as chloride attack,concrete carbonation,and wind-induced fatigue.This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds.The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered.Moreover,the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events.The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds.Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect.The contribution of each hazard event on the total structural failure probability varies with time.Thus,neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.
文摘Background What factors,processes and mechanisms regulate invasive processes and their efects?This is one of the main questions addressed by the ecology of biological invasions.Ligustrum lucidum,a tree species native to East Asia,became an aggressive invader of subtropical and temperate forests around the world.We analyzed here the L.lucidum invasion in Uruguayan forests to determine the factors controlling two stages of the invasive process,the establishment,and the dominance.Establishment was assessed by the occurrence,measured in 1525,1×1 kmcells,and dominance by remotely measuring the L.lucidum coverage at the forest canopy in 5554,1×1 km-cells.The occurrence and dominance were modeled using Generalized Linear Models in function of independent environmental and geographic variables.Results Ligustrum lucidum has become established in 13.4%of the Uruguayan forests and has dominated the forest canopy in 1.2%.Our models explained 45%and 35%of the occurrence and dominance spatial variance respectively and detected in both cases strong difusion patterns from the S-SW region to rest of Uruguay.Occurrence increased mainly in function of urban areas,and with the proximity to towns,probably because L.lucidum trees planted in gardens are seed sources,and near railways and highways,that could function as biological corridors.Occurrence also increased in loamy soils and near rivers,suggesting moisture conditions are favorable for establishment.Dominance increased with reduced forest area,in high productive soils and at higher altitudes.Moreover,dominance increased near urban areas,roads,and railways,as well as in highly aforested landscapes,and in loamy and low-rockiness soils.Conclusions The invasion of Uruguayan forests by L.lucidum is in the spread and impact stages,currently in expansion from the invasion focus on the S-SW region,where the oldest urbanizations are settled,towards the rest of the country.The geographic proximity to the invasion focus is currently the main predictor of both L.lucidum establishment and dominance.Additionally,whereas establishment is manly facilitated by human infrastructures improving propagule pressure and dispersion,dominance is enhanced in small or fragmented forest patches,in richnutrient soils,and at higher altitudes,suggesting ecosystem resistance is also operating.
文摘Introduction:Incorporating information on animal behavior in resource-based predictive modeling(e.g.,occurrence mapping)can elucidate the relationship between process and spatial pattern and depict habitat in terms of its structure as well as its function.In this paper,we assigned location data on brood-rearing greater sage-grouse(Centrocercus urophasianus)to either within-patch(encamped)or between-patch(traveling)behavioral modes by estimating a movement-based relative displacement index.Objectives were to estimate and validate spatially explicit models of within-versus between-patch resource selection for application in habitat management and compare these models to a non-behaviorally adjusted model.Results:A single model,the vegetation and water resources model,was most plausible for both the encamped and traveling modes,including the non-behaviorally adjusted model.When encamped,sage-grouse selected for taller shrubs,avoided bare ground,and were closer to mesic areas.Traveling sage-grouse selected for greater litter cover and herbaceous vegetation.Preference for proximity to mesic areas was common to both encamped and traveling modes and to the non-behaviorally adjusted model.The non-behaviorally adjusted map was similar to the encamped model and validated well.However,we observed different selection patterns during traveling that could have been masked had behavioral state not been accounted for.Conclusions:Characterizing habitat that structured between-patch movement broadens our understanding of the habitat needs of brood-rearing sage-grouse,and the combined raster surface offers a reliable habitat management tool that is readily amenable to application by GIS users in efforts to focus sustainable landscape management.
