Weak Explosion Research Articles

Basaltic explosive volcanism: Constraints from deposits and models

Basaltic pyroclastic volcanism takes place over a range of scales and styles, from weak discrete Strombolian explosions (∼10 2–10 3 kg s −1) to Plinian eruptions of moderate intensity (10 7–10 8 kg s −1). Recent well-documented historical eruptions from Etna, Kīlauea and Stromboli typify this diversity. Etna is Europe's largest and most voluminously productive volcano with an extraordinary level and diversity of Strombolian to subplinian activity since 1990. Kīlauea, the reference volcano for Hawaiian fountaining, has four recent eruptions with high fountaining (>400 m) activity in 1959, 1960, 1969 (–1974) and 1983–1986 (–2008); other summit (1971, 1974, 1982) and flank eruptions have been characterized by low fountaining activity. Stromboli is the type location for mildly explosive Strombolian eruptions, and from 1999 to 2008 these persisted at a rate of ca. 9 per hour, briefly interrupted in 2003 and 2007 by vigorous paroxysmal eruptions. Several properties of basaltic pyroclastic deposits described here, such as bed geometry, grain size, clast morphology and vesicularity, and crystal content are keys to understand the dynamics of the parent eruptions. The lack of clear correlations between eruption rate and style, as well as observed rapid fluctuations in eruptive behavior, point to the likelihood of eruption style being moderated by differences in the fluid dynamics of magma and gas ascent and the mechanism by which the erupting magma fragments. In all cases, the erupting magma consists of a mixture of melt and gaseous bubbles. The depth and rate of degassing, melt rheology, bubble rise and coalescence rates, and extent of syn-eruptive microlite growth define complex feedbacks that permit reversible shifts between fragmentation mechanisms and in eruption style and intensity. However, many basaltic explosive eruptions end after an irreversible shift to open-system outgassing and microlite crystallization in melt within the conduit. Clearer understanding of the factors promoting this diversity of basaltic pyroclastic eruptions is of fundamental importance in order to improve understanding of the range of behaviors of these volcanoes and assess hazards of future explosive events at basaltic volcanoes. The three volcanoes used for this review are the sites of large and growing volcano-tourism operations and there is a public need both for better knowledge of the volcanoes’ behavior and improved forecasting of the likely course of future eruptions.

Simulations of Magnetically Driven Supernova and Hypernova Explosions in the Context of Rapid Rotation

We present here the first 2D rotating, multi-group, radiation magnetohydrodynamics (RMHD) simulations of supernova core collapse, bounce, and explosion. In the context of rapid rotation, we focus on the dynamical effects of magnetic stresses and the creation and propagation of MHD jets. We find that a quasi-steady state can be quickly established after bounce, during which a well-collimated MHD jet is maintained by continuous pumping of power from the differentially rotating core. If the initial spin period of the progenitor core is $\sles$ 2 seconds, the free energy reservoir in the secularly evolving protoneutron star is adequate to power a supernova explosion, and may be enough for a hypernova. The jets are well collimated by the infalling material and magnetic hoop stresses, and maintain a small opening angle. We see evidence of sausage instabilities in the emerging jet stream. Neutrino heating is sub-dominant in the rapidly rotating models we explore, but can contribute 10$-$25% to the final explosion energy. Our simulations suggest that even in the case of modest or slow rotation, a supernova explosion might be followed by a secondary, weak MHD jet explosion, which, because of its weakness may to date have gone unnoticed in supernova debris. Furthermore, we suggest that the generation of a non-relativistic MHD precursor jet during the early protoneutron star/supernova phase is implicit in both the collapsar and "millisecond magnetar" models of GRBs. The multi-D, multi-group, rapidly rotating RMHD simulations we describe here are a start along the path towards more realistic simulations of the possible role of magnetic fields in some of Nature's most dramatic events.

Linking variable explosion style and magma textures during 2002 at Stromboli volcano, Italy

Microtextural characteristics of fresh ejecta from Stromboli volcano were examined from three periods of differing eruption style and intensity in 2002. Activity shifted from relatively weak and infrequent ash-charged explosions during January through May into two broad cycles of waxing activity in June through late September, and late September through December, followed by the onset on 28 December of the 2002/2003 effusive eruption. Analyzed sets of lapilli from May, September/October, and 28 December show contrasts in the physical properties of magma resident in the shallow conduit during this range of activity. Three distinct textures are observed among the analyzed pyroclasts: low density (LD) with an abundance of subspherical bubbles, the presence of large, irregularly shaped bubbles, and a light-to-transparent glass matrix; transitional texture (TT) with an intermediate number of subspherical bubbles, a high frequency of large, irregularly-shaped bubbles, and a honey colored glass matrix; and high density (HD) with sparse relatively small bubbles, conspicuous large irregular bubbles, and a dark glass matrix. Observational and quantitative data (density, vesicle size) indicate that these textures are linked through variable residence time in Stromboli’s shallow conduit, with an ongoing evolution from LD to HD magma. Calculations suggest that residual LD magma will evolve to HD texture in a period of hours to days. Contrasting amounts of the LD, TT, and HD magmas are present in each sample, with the most TT in May, the most LD in September/October, and the most HD in December. This implies that the shallow magma had a different rheology at each collection period. The viscosity of LD and HD magmas are calculated to be in the range of 2,000 to 2,600 and 3,000 to 5,000 Pa s, respectively, which, with their changing proportions, must have implications for rates of bubble slug ascent and processes of fragmentation. This study suggests that an increasing maturity of magma in Stromboli’s shallow conduit (with resultant increase in viscosity) feeds back to reduce the intensity of explosions, whereas a steady flux of LD magma favors more powerful explosions.

Explosive Nucleosynthesis from Gamma‐Ray Burst and Hypernova Progenitors: Direct Collapse versus Fallback

The collapsar engine behind long-duration gamma-ray bursts extracts the energy released from the rapid accretion of a collapsing star onto a stellar mass black hole. In a collapsing star, this black hole can form in two ways: the direct collapse of the stellar core into a black hole and the delayed collapse of a black hole caused by fallback in a weak supernova explosion. In the case of a delayed-collapse black hole, the strong collapsar-driven explosion overtakes the weak supernova explosion before shock breakout, and it is very difficult to distinguish this black hole formation scenario from the direct-collapse scenario. However, the delayed-collapse mechanism, with its double explosion, produces explosive nucleosynthetic yields that are very different from those in the direct-collapse scenario. We present one-dimensional studies of the nucleosynthetic yields from both black hole formation scenarios, deriving differences and trends in their nucleosynthetic yields.

Efficiency crisis of swift gamma-ray bursts with shallow X-ray afterglows: prior activity or time-dependent microphysics?

Context. Most X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase $\propto$$t^{-1/2}$ in the first few hours. Aims. This is not predicted by the standard afterglow model and needs an explanation. Methods. We discuss that the shallow decay requires an unreasonably high gamma-ray efficiency, $\ga$$75{-}90\%$, within current models, which is difficult to produce by internal shocks. Such a crisis may be avoided if a weak relativistic explosion occurs ~$10^3{-}10^6$ s prior to the main burst or if the microphysical parameter of the electron energy increases during the shallow decay, $\epsilon_{\rm e} \propto t^{1/2}$. The former explanation predicts a very long precursor, while both prefer dim optical flashes from the reverse shock, as was recently reported. We also calculate the multi-wavelength afterglows and compare them with observations. Results. No optical break at the end of the shallow X-ray decay indicates a preference for the time-dependent microphysics model with additionally decaying magnetic fields, $\epsilon_B \propto t^{-0.6}$.

Two-dimensional hydrodynamic core-collapse supernova simulations with spectral neutrino transport

Spherically symmetric (ID) and two-dimensional (2D) supernova simulations for progenitor stars between 11 M ⊙ and 25 M ⊙ are presented, making use of the PROMETHEUS/VERTEX neutrino-hydrodynamics code, which employs a full spectral treatment of neutrino transport and neutrino-matter interactions with a variable Eddington factor closure of the O(v/c) moments equations of neutrino number, energy, and momentum. Multi-dimensional transport aspects are treated by the ray-by-ray plus approximation described in Paper I. We discuss in detail the variation of the supernova evolution with the progenitor models, including one calculation for a 15 M ⊙ progenitor whose iron core is assumed to rotate rigidly with an angular frequency of 0.5 rad s -1 before collapse. We also test the sensitivity of our 2D calculations to the angular grid resolution, the lateral wedge size of the computational domain, and to the perturbations which seed convective instabilities in the post-bounce core. In particular, we do not find any important differences depending on whether random perturbations are included already during core collapse or whether such perturbations are imposed on a ID collapse model shortly after core bounce. Convection below the neutrinosphere sets in 30-40 ms after bounce at a density well above 10 12 g cm -3 in all 2D models, and encompasses a layer of growing mass as time goes on. It leads to a more extended proto-neutron star structure with reduced mean energies of the radiated neutrinos, but accelerated lepton number and energy loss and significantly higher muon and tau neutrino luminosities at times later than about 100ms after bounce. While convection inside the nascent neutron star turns out to be insensitive to our variations of the angular cell and grid size, the convective activity in the neutrino-heated postshock layer gains more strength in better resolved models. We find that low (l = 1, 2) convective modes, which require the use of a full 180 degree grid and are excluded in simulations with smaller angular wedges, can qualitatively change the evolution of a model. In case of an 11.2 M ⊙ star, the lowest-mass progenitor we investigate, a probably rather weak explosion by the convectively supported neutrino-heating mechanism develops after about 150ms post-bounce evolution in a 2D simulation with 180 degrees, whereas the same model with 90 degree wedge fails to explode like all other models. This sensitivity demonstrates the proximity of our 2D calculations to the borderline between success and failure, and stresses the need to strive for simulations in 3D, ultimately without the constraints connected with the axis singularity of a polar coordinate grid.

Complex proximal sedimentation from Plinian plumes: the example of Tarawera 1886

The 1886 eruption of Tarawera, New Zealand, was unusual for a Plinian eruption because it involved entirely basaltic magma, originated in a 17-km-long fissure, and produced extremely overthickened proximal deposits with a complex geometry. This study focuses on an 8-km-long segment cutting across Mount Tarawera where over 50 point-source vents were active during the 5.5-h eruption. A detailed characterization of the proximal deposits is developed and used to interpret the range of styles and intensities of the vents, including changes with time. We identify the four vents that contributed most heavily to the Plinian fall and evaluate the extent to which current volcanic plume models are compatible with the depositional patterns at Tarawera. Three proximal units are mapped that have phreatomagmatic, magmatic, and phreatomagmatic characteristics, respectively. Within the magmatic proximal unit, beds of like character are grouped into packages and delineated on scaled cross sections. Package dispersal is quantified by measuring the linear thickness half-distance (t1/2) in the planes of the fissure walls. Most packages have localized dispersals (low t1/2), indicating that Strombolian-style activity dominated most vents. The more widely dispersed packages (high t1/2) reflect contributions from additional transport regimes that were more vigorous but still contributed considerable material to the proximal region. We conclude that the geometry of the observed proximal deposits requires three modes of fall transport: (1) fallout from the upper portions of the Plinian plumes produced principally by vents in four craters; (2) sedimentation from the margins of the lower portions of the Plinian plumes including the jets and possibly the lower convective regions; and (3) ejection by weak Strombolian-style explosions from vents that did not contribute significant volumes of particles to the high plume. We suggest that the curvature of the velocity profile across the jet region of each plume (1–4 km height) was important, and that the lower velocity at the margins allowed proximal deposition of a large volume of material with a wide grain-size range.

Suppression of secondary explosions in transformer rooms

Large-scale explosion tests in a 50 m 3 room have been performed to simulate real transformer room explosions. The scale and the room layout were chosen as realistic as possible, with a moderate vent area. Prior to ignition hydrogen gas and transformer oil was sprayed into the room. Reference tests were carried out to investigate how gas concentration (i.e. energy deposited in the electric arc) and amount of oil mist would influence the explosion strength. Thereafter 3 manufacturers were invited to mitigate and suppress the explosions. The manufacturers were Atex (superheated water), Fike (powder) and Kidde (water suppression with salts added). In the initial tests showed that the amount of gas is a very important parameter for the explosion load, an implication of this is that a good circuit breaker in the transformer is important. The amount of oil mist was found to influence the explosion loads less. The suppression tests showed that for weak explosions, with average gas concentrations about lower explosion limit, all concepts reduced the explosion loads significantly. For higher gas concentrations (twice as high, still far from worst-case), only a moderate pressure reduction, or no reduction at all, was seen. Some concepts reduced the pressure impulse and flame exposure time significantly. For the strong explosions, it is assumed that performance of most systems could be improved, and suggestions for improvements for all concepts are proposed.

Collapsars: Gamma‐Ray Bursts and Explosions in “Failed Supernovae”

Using a two-dimensional hydrodynamics code (PROMETHEUS), we explore the continued evolution of rotating helium stars, Mα 10 M☉, in which iron-core collapse does not produce a successful outgoing shock but instead forms a black hole of 2-3 M☉. The model explored in greatest detail is the 14 M☉ helium core of a 35 M☉ main-sequence star. The outcome is sensitive to the angular momentum. For j16 ≡ j/(1016 cm2 s-1) 3, material falls into the black hole almost uninhibited. No outflows are expected. For j16 20, the infalling matter is halted by centrifugal force outside 1000 km where neutrino losses are negligible. The equatorial accretion rate is very low, and explosive oxygen burning may power a weak equatorial explosion. For 3 j16 20, however, a reasonable value for such stars, a compact disk forms at a radius at which the gravitational binding energy can be efficiently radiated as neutrinos or converted to beamed outflow by magnetohydrodynamical (MHD) processes. These are the best candidates for producing gamma-ray bursts (GRBs). Here we study the formation of such a disk, the associated flow patterns, and the accretion rate for disk viscosity parameter α ≈ 0.001 and 0.1. Infall along the rotational axis is initially uninhibited, and an evacuated channel opens during the first few seconds. Meanwhile the black hole is spun up by the accretion (to a ≈ 0.9), and energy is dissipated in the disk by MHD processes and radiated by neutrinos. For the α = 0.1 model, appreciable energetic outflows develop between polar angles of 30° and 45°. These outflows, powered by viscous dissipation in the disk, have an energy of up to a few times 1051 ergs and a mass ~1 M☉ and are rich in 56Ni. They constitute a supernova-like explosion by themselves. Meanwhile accretion through the disk is maintained for approximately 10-20 s but is time variable (±30%) because of hydrodynamical instabilities at the outer edge in a region where nuclei are experiencing photodisintegration. Because the efficiency of neutrino energy deposition is sensitive to the accretion rate, this instability leads to highly variable energy deposition in the polar regions. Some of this variability, which has significant power at 50 ms and overtones, may persist in the time structure of the burst. During the time followed, the average accretion rate for the standard α = 0.1 and j16 = 10 model is 0.07 M☉ s-1. The total energy deposited along the rotational axes by neutrino annihilation is (1-14) × 1051 ergs, depending upon the evolution of the Kerr parameter and uncertain neutrino efficiencies. Simulated deposition of energy in the polar regions, at a constant rate of 5 × 1050 ergs s-1 per pole, results in strong relativistic outflow jets beamed to about 1% of the sky. These jets may be additionally modulated by instabilities in the sides of the nozzle through which they flow. The jets blow aside the accreting material, remain highly focused, and are capable of penetrating the star in ~10 s. After the jet breaks through the surface of the star, highly relativistic flow can emerge. Because of the sensitivity of the mass ejection and jets to accretion rate, angular momentum, and disk viscosity, and the variation of observational consequences with viewing angle, a large range of outcomes is possible, ranging from bright GRBs like GRB 971214 to faint GRB-supernovae like SN 1998bw. X-ray precursors are also possible as the jet first breaks out of the star. While only a small fraction of supernovae make GRBs, we predict that collapsars will always make supernovae similar to SN 1998bw. However, hard, energetic GRBs shorter than a few seconds will be difficult to produce in this model and may require merging neutron stars and black holes for their explanation.

Nonlinear aspects of outdoor propagation of acoustic pulses produced by weak explosions

This paper deals with some nonlinear characteristics of acoustic pulses generated by weak explosions with regard to establishing a probe signal for the experimental study of ground characteristics and outdoor sound propagation. These explosions cover the intensity range of signals commonly used on experimental studies, e.g., studies of the impulse response of rooms and the transmission loss and absorption characteristics of noise barriers. After a brief introduction of time history and spectra of such signals, compared to linear pulses and nonlinear pulses of explosions of a higher nonlinear range particular attention is paid to air absorption up to 20 kHz. Evolution of the pulse signature as it propagates as well as global pick attenuation and attenuation in 1/3 octave frequency bands are discussed compared to linear processes and well established nonlinear theories, offering as a conclusion a simple and practical model that accounts well for the transformations undergone by the pulse when it propagates under reference atmospheric conditions. These characteristics are intended as a reference for comparison of experimental studies on the influence of the ground and obstacles of different acoustic nature involved in propagation processes. [Work supported by the Spanish National Research Program, DCICYT AMB 95-0101.]

Matter Mixing from Axisymmetric Supernova Explosion

The growth of Rayleigh-Taylor instabilities under axisymmetric explosion is investigated by two-dimensional hydrodynamical calculations. The degree of the axisymmetric explosion and amplitude of the initial perturbation are varied parametrically to find the most favorable parameter for reproducing the observed line profile of heavy elements. It is found that spherical explosion cannot produce 56Ni travelling at high velocity (~3000 km s-1), the presence of which is affirmed by observation, even if the amplitude of initial perturbation is as large as 30%. On the other hand, strong axisymmetric explosion models produce too much high-velocity 56Ni. Weak axisymmetric explosion is favored for the reproduction of the observed line profile. We believe that this result shows the upper limit of the degree of axisymmetric explosion. This fact will be important for the simulation of collapse-driven supernovae, including rotation, magnetic field, and axisymmetric neutrino radiation, which can potentially cause axisymmetric supernova explosion. In addition, the origin of such a large perturbation does not seem to be the structure of the progenitor but the dynamics of the core collapse explosion itself, since small perturbation cannot produce the high-velocity element, even if axisymmetric explosion models are adopted.

The number of radial cracks in polymethylmethacrylate in explosion of a borehole charge

The data available on the number of main radial cracks formed in a solid coarsely fracturing medium(PMMA) upon weak and strong explosion of borehole charges are generalized. A dependence of the number of radial cracks on the loading rate of the borehole walls is obtained.

95/05434 Weak coal dust explosion propagation in a mine workings network

95/05434 Weak coal dust explosion propagation in a mine workings network

Experiments on steam explosion by interaction of water with silicate melts

An experimental set-up for the generation of mixtures of silicate melt (remolten volcanic rocks) and water and the triggering of steam explosions was built at the Institut für Kernenergetik (IKE) at Stuttgart. The temperature of melts investigated ranged from 1200 to 1600°C. The chosen experimental configuration resulted in mixtures of 0.5–20 ml of water in 125 ml of melt, the water dispersed into droplets that were entrapped by domains of melt. More than 300 experimental runs were performed using a variety of remolten volcani rocks. Explosive premixtures were triggered by shock waves of less than 8 J kinetic energy. Only part of the melt and part of the water of the mixture reacted thermally, thus causing an explosion. The most intensive explosions were produced by reaction of about 3 ml of water and 6 ml of melt and released kinetic energy of more than 600 J. Higher melt viscosity resulted in weaker explosions. Higher mixing energy enhanced probability and intensity of explosions. Melt temperatures were only of minor influence. If bubbles of non-condensible gases were abundant in a mixture of otherwise explosive water/melt ratio, explosions could not be triggered.

Compositional and textural characteristics of the strombolian and surtseyan K‐Trig basalts, Taupo Volcanic Centre, New Zealand: Implications for eruption dynamics

Abstract K‐Trig basalts form a NNE lineament of four monogenetic centres, along the eastern side of the Kaiapo Fault, 4 km west of Taupo, New Zealand. Exposures of the northernmost centres (Punatekahi and K‐Trig) are dominated by strombolian volcanism, whereas the southern centres (Kaiapo and Mine Bay) are products of surtseyan activity. The Kaiapo deposit represents the faulted, eroded remnant of a once larger phreatomagmatic tuff cone. Inner‐wall stratigraphy exposed in the Kaiapo Fault scarp shows the deposit built up during three phases of phreatomagmatic volcanism, each phase comprising a lapilli‐rich lower facies A and a contrasting lapilli‐poor upper facies B. Both are interpreted as the product of multiple “wet” surges, but facies A beds are classic surtseyan products, whereas facies B beds are interpreted as having been deposited during periods of lower magma flux, when decoupled magmatic volatiles streamed through a fine‐grained vent slurry, facilitating weak steam explosions. At Punatekahi, two...

The effect of the Earth's oblateness on the long-term dispersion of debris

A model for an analytical prediction of the space debris long-term dispersion, is suggested. The main idea is to compute the variation of the secular orbital elements, assuming a weak explosion as the initial conditions. The instantaneous changes in the orbital elements due to an explosion are evaluated by the Poisson's method for small impulses. Then, the sensitivity of the secular precessing ellipse to these small impulses, is computed. These are combined to form a sensitivity matrix which formulates the long-term dispersion as a linear mapping of the initially perturbed state vector.

Neutron star accretion and the neutrino fireball

We suggest a mechanism for driving supernova explosions through neutrino energy deposition beyond the formation and the cooling of the neutron star. The mechanism depends upon convection next to the neutron star and terminates when the entropy of buoyant bubbles increases sufficiently due to neutrino heating to shut off the down flow of low entropy matter. This convection is initially caused by the heat deposited from neutrinos emitted by the cooling neutron star in a region gravitationally dominated by the neutron star. This convection by providing an efficient heat transport mechanism avoids the overheating and excessive neutrino energy losses in the regions close to the neutron stars and has been recently modeled by Herant, Benz and Colgate. In this model the explosion shock, initially driven by the bounce followed by neutron star derived neutrino heating is further driven by the up flow of the bouyant, high entropy bubbles. The down flow between the bubbles of low entropy matter originating from behind the bounce and later the explosion shock will build up a modest entropy atmosphere in pressure equilibrium with the surface of the cooling neutron star. For modest entropies, S rad ≈ 10 or S total ≈ 18 and condensed neutron stars, R/ M ≈ 10 km per solar mass, the total mass of such an atmosphere is small, 1.7 × 10 −3 M ⊙, but the temperature at the base of such an atmosphere is extremely high, T ≈ 10 MeV. The paradoxical result of neutrino emission is to further condense the atmosphere and increase the temperature until the compression heating is exceeded by the neutrino emission. The absolute limit of compression heating is free fall collapse, which may be approached but not exceeded. Such an accretion event approaching this limit may reach a temperature high enough to create a neutrino “fireball”, a region hot enough, ≈ 11 MeV, so as to be partially opaque to its own (neutrino) radiation. The further heating of the already high entropy bubbles by the neutrino deposition resulting from less extreme, but a continuing high temperature atmosphere, will augment the explosion shock. This convection-driven accretion should continue until the low entropy matter fllowing downwards onto the neutron star is mixed to a high enough entropy by entrainment with the rising high entropy bubbles to prevent further accretion. This process, by providing for a feedback mechanism, may result in a robust supernova explosion in the sense that prior processes resulting in a failed or weak explosion will be augmented with further accretion energy until an explosion of the appropriate energy occurs.

Guide to dust explosion prevention and protection — part 3: venting of weak explosions and the effect of vent ducts: BMHB, design guide for practical systems

Guide to dust explosion prevention and protection — part 3: venting of weak explosions and the effect of vent ducts: BMHB, design guide for practical systems

How much boundary layer heating occurs in an accreting prenova white dwarf?

Understanding boundary layer heating is crucial in determining the thermal structure of the accreted envelope of a prenova white dwarf. The matched asymptotic expansion method was used to solve consistently for the structure of accretion disks transferring matter onto rotating white dwarfs. The fraction of accretion energy transported into prenova white dwarf envelopes was calculated. These results should be used by modelers of nova eruptions; they will produce significantly lower degeneracies and weaker explosions than expected until now. Detailed models of accretion disks and boundary layers can also be used to calculate the amount of white dwarf heating during a dwarf nova outburst. In general, such models can serve as input to model atmosphere codes to predict more realistic spectra of disk-accreting objects. 29 refs.

Experimental research on flame spectra of methane-coal dust explosions

The significance of experimental research on flame spectra of methane-coal dust explosions is explained. Weak explosions of methane-coal dust-air mixtures were carried out in a large-scale tube of O 200 cm×2900cm with one end open, and the absolute radiation intensities as well as their variation under different conditions for characteristic wavelengths of 0.8875, 1.000, 1.505, 2.801, and 4.346μm were obtained by using small angle of view and a multichannel detector developed by us. The experimental results are discussed and compared with those published abroad. Based on the absolute radiation intensity measured at wavelength 4.346μm and the selected blackbody radiation model, the temperature of explosion flame was determined. The results obtained are not only of great practical importance to the industry but may also be used in the study of flame and chemical kinetics.