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Photos of the Tunguska blast from the 1921-29 expeditions. Near the presumed epicenter the trees were found to still be standing like "telegraph poles" with all the branches broken off, extending out 3-5 km. Further out the trees were knocked down radially outwards from the epicenter out to 20-40 km. Images reprinted with permission from the collections of the Tomsk State Archives fund P-1947 (http://tunguska.tsc.ru).
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A wide range of meteors were simulated impacting Earth's atmosphere using the ALE3D hydrocode. The size, density, strength curve, entry angle, and velocity of the meteors were varied to cover the parameter space of airbursts of interest to planetary defense in general which encompasses the Tunguska event in particular. The hydrocode simulations wer...
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... has been some debate over whether the Tunguska impactor was a comet or an asteroid with several researchers concluding that either is possible ( Korobeinikov et al., 1998;Svetsov, 1998;Shuvalov and Artemieva, 2002). Using Eq. (3), Fig. 10 shows all the possible meteors which could deliver 10 Mt of energy to an altitude of 10 km as a nominal Tunguska blast. This simplifies the energy deposition profile to a single point, but should nevertheless provide a first cut of the possibilities for the Tunguska meteor. Every point on the plane will deliver 10 Mt to 10 km using Eq. ...
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... Fig. 10 shows the range of possible meteors required to create a nominal Tunguska airburst, to produce Tunguska-like destruction depends not just on the wind speeds experienced on the ground, but also on the strength of trees in the region, as was shown earlier in Fig. 5. As a general rule of thumb ∼40 m/s is considered the critical wind speed ...
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... able to withstand typical storms and forests would not exist in such a location. However there is significant variation depending on tree species, tree spacing, soil conditions, foliage health, time of year, and typical winds experienced at a given location. There may also be additional variation between typical storm wind gusts and a blast wave. Fig. 11 shows a compilation of observed treefall during storms. Boslough and Crawford (1997) and Boslough( 2018) argued that the treefall curve from Glasstone and Dolan (1977) was too conservative for several reasons: Firstly, Tunguska is in the Siberian taiga (boreal forest) where the ground is frozen much of the year, so all tree species ...
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... limiting root depth. Secondly the forest in 1908 was not a healthy one, but had previously been damaged by wildfires in the 1800s leaving many dead and rotting trees in the area (Florenskiy, 1963). Thirdly, unlike in the Upshot-Knothole Encore nuclear test (Fig. 4), the ground was not flat, but hilly, and the most dramatic photos from Tunguska ( Fig. 1) are all from ridges facing the epicenter where windspeeds will increase going over the hill. Due to all of these effects Boslough reduced the treefall windspeeds to 40% of the ( Glasstone and Dolan, 1977) values. It should be noted that in Fig. 5 the critical wind speeds from Boslough and Crawford (1997) do not imply that 16 m/s will ...
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... in 1908, and what range of estimates is reasonable? Nemec et al. (2018) give simulations of possible airblasts over the actual Tunguska terrain. Here we concentrate on the tree windthrow resistance. Florenskiy (1963) in the 1961 expedition took a winch and a dynamometer and measured the moment required to fell the trees in the area as shown in Fig. 12. The Tunguskan forest is mostly composed of Dahurian larch (Larix Gmelinii) and Siberian pine (Pinus Sibirica). With the exception of the trees already dead in 1908 prior to the airburst, Florenskiy (1963) found no dependence of the felling moment on species, age of trees, rocky or fine soils, slope, azimuth to epicenter, or between ...
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... in Eq. (4) have unfortunately not yet been determined for Dahurian larch and Siberian pine, so we used European larch and Scots pine as surrogates. Since the airburst occurred on 30th June, the larch should have been in leaf. The tree packing is estimated at 140 trees per hectare (100 m × 100 m) based on the 35 trees per quarter hectare shown in Fig. 2 (Fast, 1967), which gives an inter-tree distance of 8.5 ...
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... versus age, spacing, soil conditions, etc, but this assumes commercially planted forests of densely packed, uniform aged, single species. ( Anyomi et al., 2017) supplementary material gives tree height and diameter data for the boreal forest in Ontario, Canada. Although the mix of species is different from the Siberian taiga, the Ontario trees Fig. 11. Compilation of observed treefalls during storms. A significant spread exists in the data between and even in the same species of tree with windspeeds as low as 20 m/s causing significant treefall in some instances, but about 70 m/s (hurricane force 5) is required to knock down all trees in all observed cases. Nuclear blast data for ...
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... of tree with windspeeds as low as 20 m/s causing significant treefall in some instances, but about 70 m/s (hurricane force 5) is required to knock down all trees in all observed cases. Nuclear blast data for ponderosa pine in concrete from Glasstone and Dolan (1977). Oak from Virot et al. (2016). Other data compiled by Anyomi et al. (2017). Fig. 12. Tree felling moment in the Tunguska area as measured by Florenskiy (1963). follow a growth curve that is almost independent of species as shown in Fig. 13. The tree height data is well fitted logarithmically, and for larch ...
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... all trees in all observed cases. Nuclear blast data for ponderosa pine in concrete from Glasstone and Dolan (1977). Oak from Virot et al. (2016). Other data compiled by Anyomi et al. (2017). Fig. 12. Tree felling moment in the Tunguska area as measured by Florenskiy (1963). follow a growth curve that is almost independent of species as shown in Fig. 13. The tree height data is well fitted logarithmically, and for larch ...
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... the felling moments from Florenskiy (1963) with the Forest-GALES model the critical wind speeds to fell the trees are calculated and shown in Fig. 14 as a function of tree diameter. For comparison the 10, 50, 90% values from Glasstone and Dolan (1977) are approximately 30, 45, 60 m/s. ForestGALES however predicts a much narrower spread of only about 10 m/s between 10% and 90% treefall for a given diameter, but that the critical windspeed increases from ∼20 to 45 m/s as the diameter ...
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... calculated the difference between windspeed on flat terrain and that going over a pyramidical hill to be a factor of 2, but using actual terrain from JAXA (2017) at Tunguska, for a 15 Mt airburst Nemec et al. (2018) only found a variation of 10 m/s, presumably due to the more rounded hills modelled. Subtracting 10 m/ s from the Ø20 cm values in Fig. 14 of 33-43 m/s for pine or 27-35 m/s for larch gives flat ground wind speeds of 23-33 and 17-25 m/s to create tree-felling windspeeds on the top of the ...
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... gathered following the event. It may be that 3-30 Mt at 5-15 km is as close as scientists will ever agree, and whether the meteor was an asteroid or a comet may also never the settled. Nevertheless refinements in the estimates are a possibility, and particularly the inclusion of probability distributions to determine which possibilities are most Fig. 14. Estimated wind speeds to fell the trees at Tunguska. Since tree diameter tapers from the ground to the treetop, they are typically measured at breast height. Both larch and pine are significantly easier to fell than the estimates of Glasstone and Dolan (1977) for mature ponderosa pine planted in concrete, but significantly more wind ...
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... the ground should be modelled using the actual topography as in Nemec et al. (2018), so as to not over or under estimate the terrain effects. Such simulations should allow more accurate prediction of the winds over the area for prediction of the treefall pattern, although the accuracy may be limited by poorly known details such as the exact forest conditions and winds at the time of the event (estimated to be southeasterly at 2-5 m s −1 (Florenskiy, 1963)). ...
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... treefall calculations presented here use several surrogates in place of actual data from Tunguska. Canopy size and wind response should be updated to Dahurian larch and Siberian pine when available. The critical windspeeds shown in Fig. 14 only give the windspeed as a function of tree diameter. ForestGALES predicts lower critical windspeeds for smaller trees, but this is assuming single height, single age stands. Within a multi-story stand the small trees will be protected from winds by the tall ones. ForestGALES_BC ( Anyomi et al., 2017) goes a step further to deal with ...
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Outage and complimentary load flow analyses of a selected 33kV primary distribution network in Ughelli Delta State, Nigeria, were carried out to depict feeder availability obtainable in the country. Outage and load flow analyses were carried out using parametric statistics and Newton-Raphson computation algorithm respectively. The results provide m...
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... There is a good illustration of this fact on Fig.2 in [Robertson and Mathias, 2019] (based on W. Fast data). ...
This paper is a continuation of a series of works, devoted to various aspects of the 1908 Tunguska event. A large number of hypotheses about its causes have been put forward already. However, so far none of them has received convincing evidence. This is probably why new hypotheses appear almost every year, not only in the mass-media, but also in scientific literature. At the same time, any hypothesis should not contradict the known facts about the event. Unfortunately, the authors of new hypotheses, as well as the authors of popular science articles, often use data, many of which turned out to be not entirely accurate, or even incorrect. In this paper some of this data will be considered. Also the history of the Tunguska research is considered in this paper. Some other aspects of the 1908 Tunguska event are considered too.
... The final flare was likely the moment where the residual mass no longer was able to withstand the pressure in front of the meteoroid (Jenniskens et al., 2022). Figure 12 shows the anticipated burst height as a function of yield strength of the Aguas Zarcas meteoroid (Robertson & Mathias, 2019). ...
The Aguas Zarcas (Costa Rica) CM2 carbonaceous chondrite fell during night time in April 2019. Security and dashboard camera video of the meteor were analyzed to provide a trajectory, lightcurve, and orbit of the meteoroid. The trajectory was near vertical, 81{\deg} steep, arriving from an ~109{\deg} (WNW) direction with apparent entry speed of 14.6 +/- 0.6 km/s. The meteoroid penetrated to ~25 km altitude (5 MPa dynamic pressure), where the surviving mass shattered, producing a flare that was detected by the Geostationary Lightning Mappers on GOES-16 and GOES-17. The cosmogenic radionuclides were analyzed in three recovered meteorites by either gamma-ray spectroscopy or accelerator mass spectrometry (AMS), while noble gas concentrations and isotopic compositions were measured in the same fragment that was analyzed by AMS. From this, the pre-atmospheric size of the meteoroid and its cosmic-ray exposure age were determined. The studied samples came from a few cm up to 30 cm deep in an object with an original diameter of ~60 cm, that was ejected from its parent body 2.0 +/- 0.2 Ma ago. The ejected material had an argon retention age of 2.9 Ga. The object was delivered most likely by the 3:1 or 5:2 mean motion resonances and, without subsequent fragmentation, approached Earth from a low i < 2.8{\deg} inclined orbit with perihelion distance q = 0.98 AU close to Earth orbit. The steep entry trajectory and high strength resulted in deep penetration in the atmosphere and a relatively large fraction of surviving mass.
... The final flare was likely the moment where the residual mass no longer was able to withstand the pressure in front of the meteoroid (Jenniskens et al., 2022). Figure 12 shows the anticipated burst height as a function of yield strength of the Aguas Zarcas meteoroid (Robertson & Mathias, 2019). The meteoroid flare at 25.1 km altitude implies that it broke when the dynamical pressure was~5 MPa, either measuring the meteoroid's compression or shear strength. ...
The Aguas Zarcas (Costa Rica) CM2 carbonaceous chondrite fell during nighttime in April 2019. Security and dashboard camera videos of the meteor were analyzed to provide a trajectory, light curve, and orbit of the meteoroid. The trajectory was near vertical, 81°s teep, arriving from an~109°(WNW) direction with an apparent entry speed of 14.6 AE 0.6 km s À1. The meteoroid penetrated to~25 km altitude (5 MPa dynamic pressure), where the surviving mass shattered, producing a flare that was detected by the Geostationary Lightning Mappers on GOES-16 and GOES-17. The cosmogenic radionuclides were analyzed in three recovered meteorites by either gamma-ray spectroscopy or accelerator mass spectrometry (AMS), while noble gas concentrations and isotopic compositions were measured in the same fragment that was analyzed by AMS. From this, the pre-atmospheric size of the meteoroid and its cosmic ray exposure age were determined. The studied samples came from a few cm up to 30 cm deep in an object with an original diameter of~60 cm that was ejected from its parent body 2.0 AE 0.2 Ma ago. The ejected material had an argon retention age of 2.9 Ga. The object was delivered most likely by the 3:1 or 5:2 mean motion resonances and, without subsequent fragmentation, approached the Earth from a low i < 2.8° inclined orbit with a perihelion distance q = 0.98 AU close to the Earth’s orbit. The steep entry trajectory and high strength resulted in deep penetration in the atmosphere and a relatively large fraction of surviving mass.
... Initial modeling used the Earth Impact Effects Program (EIEP) [41][42][43] (Table 2). Despite the program's limitations, it is commonly used for hydrocode simulations [42,43,[45][46][47][48][49][50]. Based on studies by Pierazzo et al. [51] positively comparing Autodyn with other programs (iSALE, SOVA, SPH, CTH, ALE3D) and physical experiments, we applied EIEP results to Autodyn-2D analysis [52][53][54][55][56][57][58][59][60][61][62][63][64] (Figures 19 and 20). ...
We report diverse shock-metamorphosed and melted grains from the 1908 airburst site in Russia, one of history's most significant and enigmatic cosmic events. Analysis of samples from a rimmed crater-like feature near the epicenter using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), and cathodoluminescence (CL) revealed evidence of extreme conditions. Our findings indicate heterogeneous shock pressures (~≥2 GPa) and temperatures (~≥1710°C) produced various microparticles, including FeO and aluminosilicate glass microspherules, melted quartz microspherules, carbon spherules, glass-like carbon, and melted minerals. Notably, quartz grains exhibit high-temperature melting and shock metamorphism, including planar deformation features (PDFs) and planar fractures (PFs), with some showing glass-lined internal fractures and melted silica coatings. Similarly, some feldspar grains display melted feldspar coatings. While multiple origins for these materials are possible-including an older crater and volcanism-the evidence best supports the 1908 Tunguska airburst hypothesis. The abundance of melted, shocked materials in the biomass-burning layer aligns with proposals that airburst fragments struck the Earth's Airbursts and Cratering Impacts 2025 | Volume 3 | Pages: 1-26 | e-location ID: e20250001 G. Kletetschka et al.: New Evidence of High-Temperature, High-Pressure Processes 2 surface at velocities sufficient to produce shocked quartz. The coexistence of melted particles, shock-metamorphosed minerals, and unaltered grains suggests a heterogeneous energy distribution that created shallow craters and melted surface materials. These findings advance our understanding of airburst/impact mechanics, but few people have ever observed a dangerous airburst like Tunguska, so very little is known about them. Lacking sufficient real-world data, scientists should continue modeling these dangerous low-altitude airbursts to understand them better. The Tunguska event is a valuable case study demonstrating the urgent need to improve our planetary defense strategies.
... Hydrocode modeling is commonly used for impact simulations [5,9,11,[125][126][127][128][129][130][131], and specifically, Autodyn-2D, a hydrocode program from Ansys, Inc., has seen widespread use [127,[132][133][134][135][136][137][138][139][140][141][142][143][144]. In the current study, we first modeled the Tall el-Hammam airburst using the Earth Impact Effects Program (EIEP) developed by Marcus et al. [145] and Collins et al. [129,130] Second, we input the EIEP results into Autodyn-2D (Ansys, Inc.), a hydrocode software program commonly used for modeling high-velocity airbursts and impacts [5,11,[125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][143]. ...
... Hydrocode modeling is commonly used for impact simulations [5,9,11,[125][126][127][128][129][130][131], and specifically, Autodyn-2D, a hydrocode program from Ansys, Inc., has seen widespread use [127,[132][133][134][135][136][137][138][139][140][141][142][143][144]. In the current study, we first modeled the Tall el-Hammam airburst using the Earth Impact Effects Program (EIEP) developed by Marcus et al. [145] and Collins et al. [129,130] Second, we input the EIEP results into Autodyn-2D (Ansys, Inc.), a hydrocode software program commonly used for modeling high-velocity airbursts and impacts [5,11,[125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][143]. ...
... Hydrocode modeling is commonly used for impact simulations [5,9,11,[125][126][127][128][129][130][131], and specifically, Autodyn-2D, a hydrocode program from Ansys, Inc., has seen widespread use [127,[132][133][134][135][136][137][138][139][140][141][142][143][144]. In the current study, we first modeled the Tall el-Hammam airburst using the Earth Impact Effects Program (EIEP) developed by Marcus et al. [145] and Collins et al. [129,130] Second, we input the EIEP results into Autodyn-2D (Ansys, Inc.), a hydrocode software program commonly used for modeling high-velocity airbursts and impacts [5,11,[125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][143]. For more information, see ...
A previous study presented evidence supporting the hypothesis that a low-altitude airburst approximately 3600 years ago destroyed Tall el-Hammam, a Middle-Bronze-Age city northeast of the Dead Sea in modern-day Jordan. The evidence supporting this hypothesis includes a widespread charcoal-and-ash-rich terminal destruction layer containing shock-fractured quartz, shattered and melted pottery, melted mudbricks and building plaster, microspherules, charcoal and soot, and melted grains of platinum, iridium, nickel, zircon, chromite, and quartz. Here, we report further evidence supporting a cosmic airburst event at Tall el-Hammam. Fifteen years of excavations across the city revealed a consistent directionality among scattered potsherds from individually decorated vessels, including one potsherd group distributed laterally approximately southwest to northeast across ∼22 m, spanning six palace walls. Similar trails of charred grains, charcoal, and bone fragments were also found distributed across multi-meter distances inside the destroyed city. Although an earlier report of the directionality of this debris was challenged, further evidence presented here strengthens that interpretation. We also report Middle-Bronze-Age partially melted breccia that likely formed at >2230 °C, consistent with a cosmic event. We investigated additional glass-filled fractured quartz grains using ten analytical techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), cathodoluminescence (CL), and electron backscatter diffraction (EBSD). These grains are inferred to have formed by high-pressure shock metamorphism, consistent with an earlier report that has been challenged. To test that the mode of destruction could have been an airburst, we produced a hydrocode computer model of a Type 2 or touch-down airburst, in which a high-temperature, high-pressure, high-velocity jet intersects Earth’s surface, producing meltglass, microspherules, and shock metamorphism. The modeling shows that the explosive energy released can propel high-velocity airburst fragments to strike the Earth’s surface, producing shock metamorphism and creating superficial craters potentially susceptible to geologically rapid erosion. Although the probability of such airbursts is low, the potential for substantial damage is high, especially in cities.
... Hydrocode programs are commonly used for impact simulations [1,6,[35][36][37][38][39][40][41]. For this study, we first modeled airbursts using the Earth Impact Effects Program (EIEP) by Marcus et al. [42] and Collins et al. [39,40] It is important to note that those authors caution that the methodology implemented in the EIEP is simplistic. ...
... Furthermore, Marcus et al. [42] emphasized that the results have significant uncertainties due to the limited understanding of impacts and airbursts. Even so, the EIEP and other modeling work by Collins et al. [39,40,43] is cited and used in hydrocode simulations for impact modeling [37,[44][45][46][47] and has been reported to produce consistent results [47]. ...
... The airburst generated a shockwave that toppled or snapped >80 million trees across ∼2000 km 2 in a radial pattern from ground zero [63][64][65][66]. Estimated surface wind velocities were ∼40-70 m/s (144-250 km/h), greater than an EF-3 tornado [37], and the airburst ignited fires that First, we entered the top four variables into the EIEP using the same values presented online by the creators of the EIEP, Marcus et al. [145], in their use of the EIEP for Tunguska. Next, we compared the EIEP output with known or estimated values for the Tunguska high-altitude airburst. ...
Asteroid and comet impacts can produce a wide range of effects, varying from large crater-forming events to high-altitude, non-destructive airbursts. Numerous studies have used computer hydrocode to model airbursts, primarily focusing on high-altitude events with limited surface effects. Few have modeled so-called “touch-down” events when an airburst occurs at an altitude of less than ∼1000 m, and no known studies have simultaneously modeled changes in airburst pressures, temperatures, shockwave speeds, visible materials, and bulk material failure for such events. This study used the hydrocode software Autodyn-2D to investigate these interrelated variables. Four airburst scenarios are modeled: the Trinity nuclear airburst in New Mexico (1945), an 80-m asteroid, a 100-m comet, and a 140-m comet. Our investigation reveals that touch-down airbursts can demolish buildings and cause extensive ground-surface damage. The modeling also indicates that contrary to prevailing views, low-altitude touch-down airbursts can produce shock metamorphism when the airburst shockwave or fragments strike Earth’s surface at sufficiently high velocities, pressures, and temperatures. These conditions can also produce microspherules, meltglass, and shallow impact craters. Regardless of modeling uncertainties, it is known that bolides can burst just above the Earth’s surface, causing significant damage that is detectable in the geologic record. These results have important implications for using shocked quartz and melted materials to identify past touch-down airbursts in the absence of a typical impact crater. Although relatively rare, touch-down events are more common than large crater-forming events and are potentially more dangerous.
... The Tunguska event occurred on the morning of June 30, 1908, when an object of an asteroidal or cometary nature (Robertson & Mathias 2019), with a radius of between 30 and 50 m (Hills & Goda 1993) or a diameter between 43 and 64 m (Jenniskens et al. 2019) exploded between 6 and 10.5 km above the Podkamennaya Tunguska river and damaged around 2,150 km 2 of Siberian taiga (Farinella et al. 2001). According to several studies, the energy released by the airburst could be between 3 and 50 Mt (Robertson & Mathias 2019; Jenniskens et al. 2019), although some authors mention that the most probable value could be between 10 and 15 Mt (Farinella et al. 2001;Jenniskens et al. 2019). ...
In this document we briefly review the evolution of the term meteoroid and we make several proposals for a definition, emphasizing the importance of the criteria used for it. Finally, we propose a definition based on observations rather than on the instrument of observation.
... Therefore, bearing in mind that during the oxidation of 1 kg of CO, energy q = I0 7 J is released, we obtain that the TNT equivalent of an explosion of gaseous pyrolysis products varies for the Tunguska celestial body in the range from 100 kilotons to 1.2 megatons. In particular, at E = 10 16 J, ε 0 = 0.1, the TNT equivalent of gaseous pyrolysis products is 2 × 10 14 J, which corresponds to 20% of the explosion energy of the Tunguska meteorite (Eo = 10 15 J), which was refined by comparing the calculated ignition circuits with the data [36,45]. ...
Publications are known where the problems of technogenic and space safety of the Earth are discussed, due to the possibility of man-made accident and collision with celestial bodies. It has been established that, as a rule, a major man-made or space disaster is accompanied by the occurrence of massive forest fires. In connection with the assessment of the environmental and climatic consequences of strong fires, it is of interest to predict the impact of this process on the state of the surface layer of the atmosphere. Due to the fact that full-scale research in such problems is simply impossible, methods of mathematical modeling are relevant. Below we consider the problem of the initial stage of the impact of a high-altitude source of radiant energy on the underlying surface of the Earth, covered with forest vegetation. The purpose of this study is to determine the size of the ignition zone and study the physical and chemical processes occurring in this case. In addition, on the basis of the results of the impact on the forests of the explosion of a celestial body, called the Tunguska meteorite, known from the scientific literature, its power is estimated.
... 40). Results of this study serve as validation of the PFC2D for simulating large dynamic problems, while offering a competing alternative to previous numerical estimations by using the impact-Simplified Arbitrary Lagrangian Eulerian (iSALE) method and other hydrocode-based programs [9,10,[12][13][14][15][16][17][18][19][20][21][22][23]. It is worth noticing that distinct element method (DEM) results discussed in this paper assume only dry mechanistic effects of the impact. ...
... The dynamic collapse model [11] has also been used to simulate the peak-ring formation of the Chicxulub crater. Robertson and Mathias [12] used ALE3D hydrocode to model asteroid airburst for the Tunguska meteors and concluded that both rocky asteroids and icy comets are plausible as causes for the Tunguska event. Pierazzo and Melosh [13] have also previously simulated the Chicxulub asteroid impact event using the 3D CHT hydrocode, with varying impact angles. ...
In recent years, an international consortium of research organizations conducted investigations at the Chicxulub Crater in Yucatan, Mexico, to better understand the crater’s formation mechanisms and the effects produced by the impact of the asteroid that is hypothesized to have caused one of the major life extinctions on Earth. This study aims to reproduce the asteroid’s impact mechanics by matching computer simulations obtained with the use of the distinct element method (DEM) against the latest topographic data observed across the crater footprint. A 2D model was formulated using ITASCA’s PFC2D software to reproduce the asteroid’s impact on Earth. The model ground conditions prior to impact were replicated based on available geological and geophysical field information. Also, the proposed DEM model configuration was designed to reproduce a far-field effect to ascertain the energy dissipation of the asteroid’s impact at the model’s boundaries. Impact conditions of the asteroid were defined based on previous asteroid impact investigations. A parametric analysis including the asteroid’s impact angle and the asteroid’s impact velocity was conducted to assess their influence on the crater formation process. Results of the simulations included the final crater topography and stratigraphy, stress profiles, contact force chains, and velocity fields. Numerical simulations showed that both the asteroid velocity and impact inclination play a major role in the crater formation process, and that the use of DEM provides interesting insights into impact crater formation.
... Asteroids smaller than 100 m in diameter typically break up in the air due to the pressure. As the fragments spread out, they are decelerated more rapidly by the atmosphere and heat the atmosphere at a very high rate (Robertson and Mathias 2019;Shuvalov et al. 2013;Wheeler et al. 2017). Larger or metallic asteroids typically impact the ground. ...
... Despite their high energy, there were few reports of damage from volcanic airwaves. An important exception was the extensive tree blowdown at Mount Saint Helens on May 18, 1980, which resembled photographs at Tunguska in 1908 (Robertson and Mathias 2019). The Mount Saint Helens blowdown was produced by a dusty gas mixture whose momentum was proportional to gas density times velocity; hence, high air density as well as wind speed were responsible. ...
Modern civilization has no collective experience with possible wide-ranging effects from a medium-sized asteroid impactor. Currently, modeling efforts that predict initial effects from a meteor impact or airburst provide needed information for initial preparation and evacuation plans, but longer-term cascading hazards are not typically considered. However, more common natural disasters, such as volcanic eruptions, earthquakes, wildfires, dust storms, and hurricanes, are likely analogs that can provide the scope and scale of these potential effects. These events, especially the larger events with cascading effects, are key for understanding the scope and complexity of mitigation, relief, and recovery efforts for a medium-sized asteroid impact event. This paper reviews the initial and cascading effects of these natural hazards, describes the state of the art for modeling these hazards, and discusses the relevance of these hazards to expected long-term effects of an asteroid impact. Emergency managers, resource managers and planners, and research scientists involved in mitigation and recovery efforts would likely derive significant benefit from a framework linking multiple hazard models to provide a seamless sequence of related forecasts.
