Tornado Impact Research Articles

Changes in tornado risk and societal vulnerability leading to greater tornado impact potential

Tornado risk, as determined by the occurrence of atmospheric conditions that support tornado incidence, has exhibited robust spatial trends in the United States Southern Plains and Mid-South during recent decades. The consequences of these risk changes have not been fully explored, especially in conjunction with growing societal vulnerability. Herein, we assess how changes in risk and vulnerability over the last 40 years have collectively and individually altered tornado-housing impact potential. Results indicate that escalating vulnerability and exposure have outweighed the effects of spatially changing risk. However, the combination of increasing risk and exposure has led to a threefold increase in Mid-South housing exposure since 1980. Though Southern Plains tornado risk has decreased since 1980, amplifying exposure has led to more than a 50% increase in mean annual tornado-housing impact potential across the region. Stakeholders should use these findings to develop more holistic mitigation and resilience-building strategies that consider a dynamically changing tornado disaster landscape.

Tornadoes Impacting Interstates: Service and Societal Considerations

Motorists traveling on Interstate highways are likely to have an increased vulnerability to weather hazards due to their unfamiliarity with nearby towns, limited methods to receive short-term weather information, and a general deficiency of a suitable shelter. To assess the threat, a database of 678 tornadoes, crossing primary and auxiliary Interstates across portions of the central and southeastern contiguous United States, was compiled for the period of 1990 to 2008. Approximately 17% of Interstate-crossing tornadoes impacted vehicles. Factors such as time of the day, EF-Scale rating, and travel density were examined to assess potential association with the probability of a tornado impact. This paper discusses current warning and preparedness activities in the operational meteorological community and state transportation departments, and recommends future actions and new technology to mitigate the loss of life and property from tornadoes that cross Interstate highways.

Assessment of the tornado impact on the Chernobyl new safe confinement

Assessment of the tornado impact on the Chernobyl new safe confinement

Integrated Risk-Informed Design (I-RID) methodological framework and computational application for FLEX equipment storage buildings of Nuclear Power Plants

In this research, an Integrated Risk-Informed Design (I-RID) methodological framework is developed for generating and evaluating design options for Nuclear Power Plant (NPP) structures and for providing plant decision makers with a quantitative comparison among design options based on multiple decision criteria, e.g., safety risk and cost. In the I-RID framework, simulations of underlying failure mechanisms are integrated with Probabilistic Risk Assessment (PRA) (consisting of event trees and fault trees) and a cost assessment model in a unified framework. The failure mechanisms are simulated by conducting Finite Element Analysis (FEA), and a probabilistic interface between FEA and the existing plant PRA is generated using structural reliability techniques. A causal model for cost assessment is developed, which allows for the modeling of multi-layer causal relationships among underlying contributing factors and, therefore, creates an explicit connection between cost and safety risk outputs. This paper applies the I-RID framework to the design of a storage building for the Diverse and Flexible Coping Strategies (FLEX) equipment in an NPP subjected to a potential tornado impact. Over two hundred design options are generated and evaluated, and three suggested design options with the lowest values of safety risk and cost are identified.

Finescale Assessment of Mobile Home Tornado Vulnerability in the Central and Southeast United States

Abstract Research has illustrated that tornado disaster potential and impact severity are controlled by hazard risk and underlying physical and social vulnerabilities. Previous vulnerability studies have suggested that an important driver of disaster consequence is the type of housing affected by tornadic winds. This study employs a Monte Carlo tornado simulation tool; mobile home location information derived from finescale, land-parcel data; and census enumerations of socioeconomic vulnerability factors to assess the tornado impact probability for one of the most wind hazard–susceptible demographics in the United States: mobile home residents. Comparative analyses between Alabama and Kansas are employed to highlight regional (i.e., Southeast vs Great Plains) differences in mobile home tornado risk, exposure, and vulnerability. Tornado impact potential on mobile homes is 4.5 times (350%) greater in Alabama than in Kansas because Alabama, in comparison to Kansas, is represented by 1) a greater number of mobile homes and 2) a more sprawling mobile home distribution. Findings reveal that the Southeast’s mobile home residents are one of the most socioeconomically and demographically marginalized populations in the United States and are more susceptible to tornado impact and death than illustrated in prior research. Policy makers, engineers, and members of integrated warning teams (i.e., National Weather Service, media, emergency managers, and first responders) should use these findings to initiate a dialogue and construct interdisciplinary actions aimed at improving societal and individual resilience before, during, and after hazardous weather events.

A forensic re-analysis of one of the deadliest European tornadoes

Abstract. Extremely rare events with high potential impact, such as violent tornadoes, are of strong interest for climatology and risk assessment. In order to obtain more knowledge about the most extreme events, it is vital to study historical cases. The purpose of this paper is twofold: (1) to demonstrate how a windstorm catastrophe that happened 100 years ago, such as the Wiener Neustadt, Lower Austria, tornado on 10 July 1916, can be successfully re-analyzed using a forensic approach, and (2) to propose a repeatable working method for assessing damage and reconstructing the path and magnitude of local windstorm and tornado cases with sufficient historical sources. Based on the results of the forensic re-analyses, a chronology of the tornado impact is presented, followed by a description of the key tornado characteristics: a maximum intensity rating of F4, a damage path length of 20 km and a maximum visible tornado diameter of 1 km. Compared to a historical scientific study published soon after the event, additional new findings are presented, namely the existence of two predecessor tornadoes and a higher number of fatalities: at least 34 instead of 32. While the storm-scale meteorology could not be reconstructed, rich damage data sources for the urban area of Wiener Neustadt facilitated a detailed analysis of damage tracks and wind intensities within the tornado. The authors postulate the requirement for an International Fujita Scale to rate tornadoes globally in a consistent way, based on comparable damage indicators.

How land use alters the tornado disaster landscape

This research assesses how the spatial character of land use influences tornado disaster potential at regional and metropolitan scales. Fine-scale, residential built-environment data for the Central Plains (regional) and Wichita, KS (metropolitan) domains are used in a Monte Carlo tornado simulation framework to estimate significant tornado impact magnitude and disaster potential. The land use patterns of the domains are hypothetically adjusted using the 2010 observed data surface as a baseline to explore how the density and spatial character of land use affects the possibility of significant tornado impacts. As residential built-environment density is reduced and the footprint of developed land grows, tornado impact probability and magnitude increases. Conversely, restricting sprawl while, at the same time, adopting a more concentrated land use pattern, lowers the odds of tornado impact and disaster. Results reveal that the geographic character of land use is important in determining an area's tornado disaster potential. This finding is especially unique and critical for develop proactive disaster mitigation strategies. Pre-disaster mitigation efforts such as effective land planning and building code improvement and enforcement are required to reduce future tornado impacts.

Finite Element Analysis of Saferooms Subjected to Tornado Impact Loads

A Tornado is one of the most dreadful and unpredictable events in nature. Unfortunately, weather and geographic conditions make a large portion of the United States prone to this phenomenon. Tornado saferooms are monolithic reinforced concrete protective structures engineered to guard against these natural disasters. Saferooms must withstand impacts and wind loads from EF-5 tornadoes – where the wind speed reaches up to 150 m/s (300 mph) and airborne projectiles can reach up to 50 m/s (100 mph). The objective of this work is to evaluate the performance of a saferoom under impact from tornado-generated debris and tornado-dragged vehicles.Numerical simulations were performed to model the impact problem using explicit dynamics and energy methods. Finite element models of the saferoom, windborne debris, and vehicle models were studied using the LS-DYNA software. RHT concrete material was used to model the saferoom and vehicle models from NCAC were used to characterize damage from impacts at various speeds. Simulation results indicate good performance of the saferoom structure at vehicle impact speeds up to 25 meters per second. Damage is more significant and increases nonlinearly starting at impact velocities of 35 m/s (78 mph). Results of this study give valuable insight into the dynamic response of saferooms subjected to projectile impacts, and provide design considerations for civilian protective structures. Further work is being done to validate the models with experimental measurements.

Projected 21st century changes in tornado exposure, risk, and disaster potential

While risk and associated hazard characteristics are important components of disaster formation, the consequences of hazards are often driven by underlying human and built-environment vulnerabilities. Yet, there has been little research conducted on how the evolving contributors of risk and vulnerability commingle to produce disaster potential. In this study, we assess the interaction of risk and vulnerability by investigating a single hazard, the tornado. How future changes in risk and vulnerability influence tornado disaster probability is estimated by integrating, for the first time, projected residential built environment data and modeled future severe weather environments. Results suggest that, although the projected twenty-first century escalation in tornado risk will play a role in increasing disaster consequences and frequency, growth in the human-built environment is projected to outweigh the effects of increased risk on future tornado disaster potential. While changes in societal exposure are projected to overshadow potential climate change-driven alterations in tornado risk, the combination of both an increase in risk and exposure may lead to a threefold increase in median annual tornado impact magnitude and disaster potential from 2010 to 2100.

A Monte Carlo model for estimating tornado impacts

ABSTRACTDetermining the likelihood and severity of tornado disasters requires an understanding of the dynamic relationship between tornado risk and vulnerability. As population increases in the future, it is likely that tornado disaster frequency and magnitude will amplify. This study presents the Tornado Impact Monte Carlo (TorMC) model, which simulates tornado events atop a user‐defined spatial domain to estimate the possible impact on people, the built‐environment or other potentially vulnerable assets. Using a Monte Carlo approach, the model employs a variety of sampling techniques on observed tornado data to provide greater insight into the tornado disaster potential for a location. Simulations based on 10 000 years of significant tornado events for the relatively high‐risk states of Alabama, Illinois and Oklahoma are conducted to demonstrate the model processes, and its reliability and applicability. These simulations are combined with a fine‐scale (100 m), residential built‐environment cost surface to illustrate the probability of housing unit impact thresholds for a contemporary year. Sample results demonstrate the ability of the model to depict successfully tornado risk, residential built‐environment exposure and the probability of disaster. Additional outcomes emphasize the importance of developing versatile tools that capture better the tornado risk and vulnerability attributes in order to provide precise estimates of disaster potential. Such tools can provide emergency managers, planners, insurers and decision makers a means to advance mitigation, resilience and sustainability strategies.

Toward Development of the Tornado Impact-Community Vulnerability Index

Given the recognition that not only physical processes, but also social, political, and economic aspects of hazards determine vulnerability to and impact of an event, a classification system that addresses those factors is needed. Current classifications for natural disasters, such as the Fujita Scale for tornadoes and the Saffir-Simpson hurricane scale, focus on the physical properties of the event, not the impact on a community. Pre-event vulnerability to a natural hazard is determined by factors such as age, race, income, gender, infrastructure, density of the built environment and health of the industrial base. The behavior of residents in the community, construction quality of shelters, and warning system effectiveness also affect vulnerability. If vulnerability is influenced by such factors, post-event impact should be, at least in part, as well. The goal of this research was to develop the Tornado Impact- Community Vulnerability Index (TICV) that utilizes variables such as the number of persons killed, economic impacts, and social vulnerability to describe to the level of impact a tornado event has on community. As tornadoes that strike unpopulated areas are often difficult to classify, even in the traditional sense, the TICV will take into consideration only events that strike communities defined as “places” according to the U.S. Census Bureau. By assigning a rating to the impact, this index will allow the severity of the storm to be understood in terms of its effect on a specific community and hence its impact, rather than in terms of its physical strength.

Criteria for NPP industrial site flooding by combined impact of tornadoes and earthquakes in the cooling pond

The results of analysis of the impact of extreme natural phenomena on safety of nuclear power plants in Ukraine, held in the pre and post-Fukushima periods have shown that tornadoes and earthquakes are the most likely events. However, the results are contradictory in relation to probability assessment of security-critical tornadoes, and do not take into account the possibility of the NPP industrial site flooding under the combined effect of tornadoes and earthquakes in the station reservoirs. Hydrodynamic model of NPP industrial site flooding wave during tornadoes and earthquakes, based on the assumption of the flooding wave formation under the influence of tornado lift and seismic shock, as well gravity and internal dissipation forces; cylindrical shape of the flooding wave; conservative isothermal exposure of the flooding wave near the coast was developed. The flooding wave emergence and development process is conventionally divided into two different time-scale phases: the initial phase of the combined (in general) earthquake and tornado, the final stage of the tornado impact. Based on the developed hydrodynamic model, deterministic criteria of possible NPP industrial site flooding at the combined (in general) impact of the tornado and earthquake in the cooling pond were defined. The analysis was performed on the example of the Zaporizhzhya NPP, due to which it was found that there was no flooding under tornadoes below the 2-intensity grade and earthquakes with response acceleration at the cooling pond bottom of less than 10 m/s 2 and duration of about ten seconds.

Twitter as a Potential Disaster Risk Reduction Tool. Part III: Evaluating Variables that Promoted Regional Twitter Use for At-risk Populations During the 2013 Hattiesburg F4 Tornado.

Introduction: Study goals attempt to identify the variables most commonly associated with successful tweeted messages and determine which variables have the most influence in promoting exponential dissemination of information (viral spreading of the message) and trending (becoming popular) in the given disaster affected region.Methods: Part II describes the detailed extraction and triangulation filtration methodological approach to acquiring twitter data for the 2013 Hattiesburg Tornado. The data was then divided into two 48 hour windows before and after the tornado impact with a 2 hour pre-tornado buffer to capture tweets just prior to impact. Criteria-based analysis was completed for Tweets and users. The top 100 pre-Tornado and post-Tornado retweeted users were compared to establish the variability among the top retweeted users during the 4 day span. Results: Pre-Tornado variables that were correlated to higher retweeted rates include total user tweets (0.324), and total times message retweeted (0.530). Post-Tornado variables that were correlated to higher retweeted rates include total hashtags in a retweet (0.538) and hashtags #Tornado (0.378) and #Hattiesburg (0.254). Overall hashtags usage significantly increased during the storm. Pre-storm there were 5,763 tweets with a hashtag and post-storm there was 13,598 using hashtags.Conclusions: Twitter’s unique features allow it to be considered a unique social media tool applicable for emergency managers and public health officials for rapid and accurate two way communication. Additionally, understanding how variables can be properly manipulated plays a key role in understanding how to use this social media platform for effective, accurate, and rapid mass information communication.

Tornado Damage and Impacts on Nuclear Facilities in the United States

This report provides an overview of the tornado impact on the safe operation and shutdown of nuclear power plants in the United States. The motivation for this review stems from the damage and failure of the Fukushima nuclear power plant on March 11, 2011. That disaster warrants comparison of the safety measures in place within the global nuclear power industry.

Visualization of tornado-like vortex interacting with wide tornado-break wall

A three-dimensional CFD model, based on large eddy simulation, is utilized to numerically simulate a perpendicular interaction between a traveling tornado-like vortex and a wide rigid wall. The tornado-like flow is modeled by the Rankine-Combined Vortex Model. The case, where the wall width is much larger than the tornado vortex core diameter is examined. The main goal of the paper is to improve the understanding of the dynamics of the tornado–wall interaction. The conclusions drawn in this study are supported by various visualizations. During the tornado impact, the structure of the tornado-like vortex is substantially mitigated by the wide wall. The low-level portion of the vortex is disturbed both in front of the wall and behind the wall. When the vortex is approaching the wall, the vortex-induced velocities cause a boundary layer separation from the leading face of the wall. The ejected, from the wall, vorticity patches wrap around the tornado-like vortex causing its weakening. Behind the wall the tornado vortex is subjected to the turbulent flow that further disrupts the tornado vortex structure. The tornado-like vortex mitigation results in a low wind speed region behind the tornado-break wall, where the wind velocities are reduced by more than 50 %.

Viewing Tornado Impact as More Than Physical Magnitude

Ten years ago this fall, an F3 tornado tore a path straight through the heart of Ladysmith, a small Northern Wisconsintown. I grew up a few cities over, and spent many weekends at the Army Reserve ...

Ground beetle (Coleoptera, Carabidae) assemblages inhabiting Scots pine stands of Puszcza Piska Forest: six-year responses to a tornado impact

Ground beetle assemblages were studied during 2003-08 in the Pisz Forest by comparing stands disturbed by a tornado to undisturbed control stands. The following exploratory questions were put forward. (1) How do the carabid assemblages change during six years following the tornado impact? (2) Does the carabid assemblage recovery begin during the six first post-tornado years? To assess the state of carabid assemblages we used two indices: the MIB (Mean Individual Biomass) and the SPC (Sum of Progressive Characteristics). Carabid assemblages in the disturbed and in the control stands, as expressed by these two indices, were compared using the length of a regression distance (sample distance in a MIB:SPC coordinate system). A cluster analysis revealed that the assemblages of the disturbed and the control stands were different. The tornado-impacted stands produced lower carabid catch rates, but species richness was significantly higher there than in the control stands. They hosted lower proportions of individuals of European species, of large zoophages, and of forest and brachypterous species, than the control stands. The observed reduction in SPC and MIB, and an increase in the regression distances may indicate that the carabid assemblages had not started to recover from the tornado-caused disturbance. Carabid assemblages apparently responded to the tornado in two steps. Firstly, the first three years were characterized by moderate decreases of index values. Secondly, from the fourth to the sixth year after the tornado, many observed changes became magnified. We did not observe clear signals of the recovery of forest carabid assemblages during the six follow-up years.

Prepare, plan, practice

Prepare, plan, practice

Effects of Urban Sprawl on the Vulnerability to a Significant Tornado Impact in Northeastern Illinois

A sprawling U.S. population continues to spread into the fringes of urban development placing both populations and property in areas that were once largely unoccupied. Population tallies, housing unit totals, and housing values for 1990 and 2000 are examined to determine the extent to which this growth has affected the tornado hazard in northeastern Illinois. The growing town of Plainfield, Ill., located southwest of Chicago, is examined to determine how vulnerability to a tornado impact has changed in the town since an F5 tornado struck the community in 1990. The population and housing data indicate an increase of 8,629 persons and 3,058 housing units affected if the tornado were to have occurred in 2000 rather than 1990. Estimations of housing value affected by the Plainfield tornado indicate a 50% increase in 2000 compared with 1990 values. In addition to studying the impacts on Plainfield, four other scenarios are examined in suburban Chicago counties using the 1990 Plainfield tornado as a model for a potentially devastating strike. The large increase in total value of homes affected for each scenario highlights the overall increase in wealth throughout the study area, specifically along the urban fringe of development. The physical vulnerability throughout the study area has increased with the rise in population, but the most socially vulnerable areas appear to remain in the older urban centers.