Large Urban Fires Research Articles

Large Fires and Climatic Variability in Urban Europe, 1500–1800

Several hundred large urban fires occurred in Europe during the early modern period, but they did not take place randomly. This article charts their incidence and reveals a peak in the seventeenth century, coinciding with some of the coolest periods of the Little Ice Age. This apparent paradox can best be explained by climatic variability, since overall cooling was accompanied by numerous warm, dry anomalies. While the cause of fires was usually human activity, and small fires happened frequently, this paper shows that many of the largest conflagrations of the early modern period took place in years of such hot and/or dry climatic anomalies, and closer analysis of individual fires confirms that these meteorological conditions facilitated their spread. This strongly suggests that climatic variability associated with the Little Ice Age was a major determinant of the timing of large fires in Europe. Over the same broad period, climatic disasters linked to cooler and damper conditions contributed to social and political instability, and there is evidence that this in turn undermined fire prevention and control and thus further increased the likelihood of small fires becoming large ones.

Special Issue on the 100th Anniversary of the Great Kanto Earthquake

On September 1, 1923, the Great Kanto Earthquake struck the Tokyo metropolitan area of Japan. It was an extremely powerful earthquake that caused a great fire. The death toll reached approximately 105,000, and the economic loss is estimated to have exceeded 30% of the Japanese gross national product at that time. For September 2023, the Journal of Disaster Research (JDR) has planned a special issue to commemorate 100 years since the Great Kanto Earthquake. While previous special issues by the JDR have focused on specific disasters, this special issue will focus on the lessons and findings from the catastrophe and will cover even the progress of disaster research since then. We received fourteen important and thought-provoking manuscripts not only on scientific and engineering aspects but also on social and cultural aspects, including comparisons with other disasters, historical views, reconstruction issues, and future perspectives. These fourteen articles can be categorized into the three groups described below. The first four articles are the English translations of articles that originally appeared in “Koho Bosai,” the bimonthly journal on natural disaster reduction that is complied and published by the Disaster Management Section, Cabinet Office, Government of Japan. The JDR believes that these four articles provide a concise English description of various aspects of the Great Kanto Earthquake disasters. Dr. Takemura summarizes the seismic features of the 1923 Kanto Earthquake. Dr. Sekizawa summarizes the large scale urban fires that it caused. Dr. Suzuki describes various aspects of the emergency responses. Dr. Murosaki details the recovery project in Tokyo. Those articles discussed various lessons learned from the 1923 Kanto Earthquake and emphasized the importance of transferring the lessons toward future disaster mitigation. The next six papers were originally works studying various aspects of the Great Kanto Earthquake disasters. Dr. Midorikawa reviews the strong ground motion of the 1923 Kanto Earthquake. Dr. Kaneko evaluates the resulting tsunami. Mr. Mammen sheds new light on the relationship between Charles A. Beard and Goto Shinpei in terms of the recovery. Dr. Albini studies the voices of foreign residents who left impressive disaster processes at that time. Dr. Murao reviews the urbanization of Tokyo after the Kanto Earthquake. Dr. Shima studies the response of the Tokyo Electric Light Company, Inc. to the 1923 Great Kanto Earthquake. The last four papers are works on various aspects of disaster risk reduction, but all of these works were inspired by the 1923 Great Kanto Earthquake in one way or another. Dr. Shaw provides a framework for repositioning earthquake risk reduction. Dr. Shimbo explores the Phase Free Concept. Dr. Shoji focuses on the possibility of Medium-Wave AM Radio Broadcasting. Dr. Yamaguchi studies the Risk Communication Method. The Editorial Board of the JDR thanks all of these contributors and hopes that these articles serve as great sources for further research in disaster risk reduction.

Lead from Notre-Dame Fire Plume Caught 15 km from Paris

Thanks to the use of filters collected daily in the west of Paris, we confirm the passage of the lead-laden plume following the fire on the roof and spire of Notre-Dame Cathedral in April 2019. The measured concentrations on the filter (Pb = 1.4 μg m–3), scanning electron microscopy and Hysplit simulation, correspond to an estimate of a few hundred kilograms of lead that would have been volatilized and then oxidized in the form of micronic and submicronic aerosols. The concentrations found in the plume are, however, much lower than those found in the environment in the 1980s and 1990s but are 100 times higher than those found in times prior to and after the fire. The isotopic signature of the plume is almost identical to that of the fine Pb dust found inside the Notre-Dame building. It is different from the isotopic signature of the Parisian atmosphere before and after the fire, but it is similar to that of the atmospheric Pb legacy recorded by peat cores over the last 300 years in France. The presence of very fine lead-bearing particles makes them potentially transportable over long distances after large urban fires. Our study shows the value of daily aerosol sampling to retrospectively trace the plumes of air pollutants from industrial accidents but also from historical monument fires such as Notre-Dame in 2019.

On Unraveling Community Ignition Processes: Joint Influences of Firebrand Showers and Radiant Heat Applied to Fuel Beds

ABSTRACT Devastating large outdoor fires have been responsible for the destruction of vast amounts of infrastructure and the loss of human life. Wildland fires that spread into urban areas, known as wildland-urban interface (WUI) fires, are capable of enormous destruction. WUI fires are distinct from wildland fires; WUI fires include the combustion of both vegetative and human-made fuels and occur where population centers exist, whereas wildland fires include the combustion of vegetative fuels and occur in uninhabited areas. The rise of densely populated urban areas has also seen the development of large urban fires. In addition, the rise of informal settlement communities in Southeast Asia and Africa continues to result in large outdoor fires capable of great destruction. As a wildland fire reaches an urban area, structure-to-structure fire spread processes will occur via the same mechanisms as those in informal settlement fires and urban fires: radiant heat, direct flame contact, and firebrands. Firebrands are in fact the main culprit to destroy structures in large outdoor fires. An additional complication is related to the showers of firebrands produced in large outdoor fires from vegetative and structural fuel combustion, and in the presence of the combustion of these fuel types, there is also radiant heat produced that may only enhance ignition processes. These combined ignition processes have been overlooked and are the subject of this experimental investigation. To this end, a custom experimental apparatus that produces firebrand showers, in the presence of applied radiant heat, was installed inside a wind facility. The firebrand generator was tuned to produce firebrands typical of those quantified from the combustion of structures and the coupled influences of firebrand showers and radiant heat, under various wind speeds was determined. The total firebrand mass for smoldering ignition (SI) decreased as the wind speed and preheating time increased. In all experiments, SI was observed to transition to flaming ignition (FI). To better understand the experimental observations, a simple model was developed and is presented.

Examining the Climate Effects of a Regional Nuclear Weapons Exchange Using a Multiscale Atmospheric Modeling Approach

AbstractRecent studies examine the potential for large urban fires ignited in a hypothetical nuclear exchange of one hundred 15 kt weapons between India and Pakistan to alter the climate (e.g., Mills et al., 2014, https://doi.org/10.1002/2013EF000205, and Reisner et al., 2018, https://doi.org/10.1002/2017JD027331). In this study, the global climate forcing and response is predicted by combining two atmospheric models, which together span the micro‐scale to global scale processes involved. Individual fire plumes are modeled using the Weather Research and Forecasting (WRF) model, and the climate response is predicted by injecting the WRF‐simulated black carbon (BC) emissions into the Energy Exascale Earth System Model (E3SM) atmosphere model Version 1 (EAMv1). Consistent with previous studies, the radiative forcing depends on smoke quantity and injection height, examined here as functions of fuel loading and atmospheric conditions. If the fuel burned is 1 g cm−2, BC is quickly removed from the troposphere, causing no global mean climate forcing. If the fuel burned is 16 g cm−2 and 100 such fires occurred simultaneously with characteristics similar to historical large urban firestorms, BC reaches the stratosphere, reducing solar radiation and causing cooling at the Earth's surface. Uncertainties in smoke composition and aerosol representation cause large uncertainties in the magnitude of the radiative forcing and cooling. The approximately 4 yr duration of the radiative forcing is shorter than the 8 to 15 yr that has previously been simulated. Uncertainties point to the need for further development of potential nuclear exchange scenarios, quantification of fuel loading, and improved understanding of fire propagation and aerosol modeling.

Detection of pre-industrial societies on exoplanets

AbstractApproximately 22% of sun-like stars have Earth-like exoplanets. Advanced civilizations may exist on these, and significant effort has been expended on the theoretical analysis of planetary systems, and accompanying practical detection instruments.The longevity of technological civilizations is unknown, as is the probability of less advanced societies becoming technological. Accordingly, searching for pre-industrial extra-terrestrial societies may be more productive.Using the earth as a model, a consideration of possible detectible proxies suggests that observation of seasonal agriculture may be possible in the near future – particularly in ideal circumstances, for which quantitative analysis is provided. More speculatively, other detectible processes may include: species introduction; climate change; large urban fires and land-use or aquatic changes.Primitive societies may be both aware that their activities may be observed from other planets, and may deliberately adjust these activities to aid or conceal detection.

Large Urban Fires in Japan: History and Management

Wildland fires and wildland–urban interface (WUI) fires quite often become the focus of discussion among fire researchers whenever large outdoor fires are the topic, especially because of their global occurrence and their potential for causing serious damage. But at the same time, large urban fires have been occurring in Japan especially after major earthquakes or with high winds, at densely built urban area consisting of old wooden houses. Normally, fire spread is caused by three mechanisms: flame, radiation, and firebrands, especially in the cases of wildland fires, WUI fires, and large urban fires. And what is common between WUI fires and large urban fires is structure–structure fire spreading. In Japan, “Taika” (large urban fire) is a fire when the total burnout floor area is 33,000 m2 or more. The present paper first discusses the history of large urban fires in Japan, then examines the national standard regulations for fire safety in Japan aimed at mitigating the damage caused by those fires. Finally, an overview of current scientific research in methods of controlling urban fires in Japan is provided. This paper compiles such impotent information on large urban fires in Japan, which is the novelty and merit in this work. Furthermore, the contents in this paper will be contributing to the progress of new project ISO/TR 24188 on “Large outdoor fires and the built environment—Global overview of different approaches for standardization”, at ISO/TC92/WG14 “Large outdoor fires and the built environment”.

Thermally-driven vortex resulting from the linear heat wires of different shapes under cross wind

Fire whirl is a typical thermally-driven vortex which often occurs in large forest and urban fires. This paper presents an experimental study of the thermally-driven vortex induced by the linear heat wire under cross wind. The straight, C- and S-shape wires were designed to simulate the fire front of different shapes. A wide range of heat release rate per length and wind speed were used to test the critical conditions under which vortex flows occur. It is found that the vortex can appear over and away from the heat wire under certain conditions. As the wire shape became complex from the straight to C-shape and to S-shape, the clockwise vortex was firstly observed and then was replaced by the vortex pair that rotated oppositely. The critical conditions of strong vortex over the heat wire well follow the previous dimensionless correlation that couples the heat release rate per length and wind speed, but the characteristic length should be different for the three types of wires. A physical mechanism of vortex formation is proposed, which indicates that the boundary vorticity near the ground surface is the possible eddy source for the vortex formation under critical conditions. The conditions of similar vortex phenomena induced by S-shape wires of two different length scales follow the previous scaling law that was built for straight line fires, but the interaction of upward thermal plume over S-shape wire results in a minus intercept of linear fitting. This work can provide a positive reference for the numerical simulation of the fire spread under cross wind.

Quantifying Wind-Driven Firebrand Production from Roofing Assembly Combustion.

Large outdoor fires present a risk to the built environment. Examples often in the international media reports are wildfires that spread into communities, referred to as Wildland-Urban Interface (WUI) fires. Other examples are large urban fires including those that have occurred after earthquakes. Firebrands are a key mechanism on how rapidly fires spread in urban fires and WUI fires. An experimental protocol has been developed to ignite full-scale roofing assemblies and quantify the degree of firebrand production during the combustion process. As wind is an important factor in firebrand generation, the experiments were conducted under a range of wind speeds at the Building Research Institute's (BRI) Fire Research Wind Tunnel Facility (FRWTF). A further unique aspect of this work is the experimental results are compared to firebrand size and mass distributions collected from an actual large-scale urban fire in Japan. Results of these experiments demonstrate that when only oriented strand board (OSB) is applied as sheathing, a significant number of firebrands collected from roofing assemblies were less than 1 g and 10 cm2. It was also observed that experiments on individual building component firebrand generation provided useful insights into actual urban fire firebrand generation.

Experimental Study on Flame Height and Radiant Heat of Fire Whirls

Fire whirls occur occasionally in wild land fires and large scale urban fires. When a fire whirl occurs, the height of flame increases significantly and the fire damages could become more severe. In this study, small and middle scale experiments (up to 20 cm in diameter) were performed to understand the mechanisms of the flame height increase at fire whirls. In the experiments, fire whirls were established on a fuel pool using a fixed-frame-type fire whirl generator. At the small scale pools (\( d \le 5\,{\text{cm}} \)), the flame behaved as a laminar diffusion flame and the measured flame height almost agreed with our scale model based on Burke–Schumann theory. Meanwhile, at the middle scale pools (\( d \ge 10\,{\text{cm}} \)), the flame comes away from a laminar diffusion flame. The measured flame height was correlated to the dimensionless heat release rate at the conditions without swirling flow and also with swirling flow. The measured data at the middle scale pools almost laid on a line of slope 2/3 in the logarithmic diagram between the flame height and dimensionless heat release rate. Also the radiant emittance and shape of base part flame, which were important to understand the fire whirl phenomena, have been examined. It was found that the radiant emittance of flame increased considerably by the swirling flow at the middle scale pools. It was also confirmed experimentally that the viscous effect near the floor (Ekman layer) made the base part flame approach to the fuel pool.

Overview of some radiative transfer issues in simulation of unwanted fires

Fire is an extremely complex phenomenon that is responsible for loss of human life and considerable property and environmental damages every year around the world. Significant progress during the last few decades in modeling of pool, compartment (enclosure), urban and outdoor (i.e., forest and woodland) fires has manifested in improved understanding of fire phenomenology, fire-safety regulations and fire-fighting techniques. Recent research efforts to develop numerical CFD (computational fluid dynamics) models for simulating fire phenomena from first principles are discussed. Since both thermal and oxygen-limited feedback processes can affect fire dynamics, quantitative description of fire development requires understanding of materials, turbulence, chemical kinetics, heat and mass transfer, radiation, and other important physical processes. Focus in the discussion is on radiative transfer (one of the most complex and time consuming process) in numerical simulation of large pool, compartment, urban and outdoor fires. The overview discusses current trends and identifies the outstanding problems requiring research attention.

The role of uncertainty in nuclear winter modelling

inherent in models of the nuclear winter phenomenon, with specific reference to the nuclear winter base term. The ‘base term’ refers to the amount of smoke injected into the atmosphere from fires ignited in a hypothetical nuclear exchange. The author examines the implications of uncertainty for estimating inputs to atmospheric circulation models used to assess the magnitude of the nuclear winter phenomenon. This is achieved through a set of experiments designed to assess the effects of variations in the spatial distribution of combustible materials on the dynamics of large urban fires. These experiments are based on an urban fire model applied to a dataset depicting the spatial distribution of combustible materials in urban areas, as derived from air photo interpretation techniques. Results indicate that the use of realistic models of the spatial distribution in place of the more common uniform and stepfunction models introduces additional uncertainty into base term estimates, due to an increase in variability in the amount of material available for ignition and an enhanced capability for fire spread in a spatially heterogeneous environment. This study shows that, paradoxically, the incorporation of more detailed information into nuclear winter base term models may introduce additional uncertainty into model outputs.

Measurements of the optical properties of the smoke emissions from plastics, hydrocarbons, and other urban fuels for nuclear winter studies

We have measured the optical and microphysical properties of smoke from burning plastic materials and other components of the urban fuel mix, including hydrocarbons, rubber, and wood, to provide information on the source term for possible aerosol clouds injected into the atmosphere following large scale urban fires. Our measurements included measurements of emission factors; in situ optical measurements of aerosol absorption, scattering, and attenuation; and collection of particles using both filters and cascade impactors for size and mass concentration determinations. These measurements were made under a variety of conditions to investigate the range of variation of these optical parameters and to relate observed differences in smoke properties to differences in fuel composition and fire conditions. The plastic data show average B e values near 10 m 2 g −1 at 488 nm and 8 m 2 g −1 at 633 nm. Values of B e measured during smoldering combustion are significantly less than in flaming combustion. Flaming combustion B e values for the rubber appear to be somewhat higher, particularly for the tire rubber; petroleum product fuel values are comparable to the plastic fuel values; and oak smoke emissions values are slightly lower than the plastic values. Measured 633 nm B a values were approximately 6 m 2 g −1 for the petroleum products, 7 m 2 g −1 for the rubber, 6 m 2 g −1 for the wood, and 6 m 2 g −1 for the plastic.

Estimation of the magnitude and spatial distribution of combustible materials in urban areas. A case study of the San Jose area, California

AbstractThis paper describes a methodology for estimating the magnitude and spatial distribution of urban fuel loadings using San Jose, California, as a case study. The study was undertaken to provide basic inputs into the modeling of large urban fires ignited by nuclear explosions, which has important implications for studies of the global climatic effects of nuclear war, or the so‐called ‘nuclear winter’ phenomenon. The methodology is based on the measurement of the numbers and sizes of different building occupancy types from aerial photographs for approximately 6000 1000‐ft (304.8‐m) grid cells covering the study area. These measurements were combined with literature‐derived average fuel loadings for each building type to yield the total fuel loading per cell. The total fuel loading thus calculated is approximately 4558.56 × 106 kg, yielding an average of 8.4 kg m−2 (1.7 lb ft−2) for the built‐up area of the city and 9.4 kg m−2 (1.9 lb ft−2) if unoccupied cells (i.e. cells containing no fuel) within the built‐up area are excluded. These figures are lower than previously published average values, due to the low‐density character of San Jose and the exclusion of certain components of total fuel loading by the methodology.

Gross vortex activities in a simple simulated urban fire

A report is hereby given to the results of an originally seemingly inconspicuous burn in a simple simulated urban street arrangement which is inductive to probable gross vortex formation. These results reveal in vivid details a series of most unusual and exciting events of gross vortex development and their related fire-brand spotting activities. These findings point to a promise of an understanding of, among other things, some of the strangest fire behaviors obsered in large urban fires.