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7. Flight routes of the 1999 aero-photosurvey exact time, 00 h 14 m 28 s UT (Ben-Menahem 1975), the coordinates of the point usually called epicenter, 60° 53' 09" N, 101° 53' 40" E (Fast 1967), the energy release, equivalent to 10-15 million tons of TNT (Megaton) that corresponds to about one thousand times
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Longo G.: "The Tunguska event" . Chapter 18, pp. 303-330 in the book: "Comet/Asteroid Impacts and Human Society, An Interdisciplinary Approach, Bobrowsky, Peter T.; Rickman, Hans (Eds.)." , 546 p., © Springer-Verlag, Berlin Heidelberg New York, 2007
In the early morning of 30th June 1908, a powerful explosion over the basin of the Podkamennaya Tu...
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Citations
... The blast yield of this airburst is estimated at ∼3-30 megatons of TNT equivalent with a burst altitude of ∼5-10 km. The airburst generated a shock wave that toppled or snapped >80 million trees across ∼2000 km 2 in a radial pattern [51,84,163,164]. Estimated surface wind velocities were ∼40-70 m/s (144-250 km/h), greater than an EF-3 tornado [127], and the airburst ignited fires that consumed ∼500 km 2 of forest [163]. ...
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.
... The direction of the meteor and the kinetic energy of the impact were also studied in much detail to provide clues about the nature of the impactor (Shapley, 1930;Whipple, 1930Whipple, , 1934Astapovich, 1934;La Paz, 1948;Jankowski, 1960;Vasiliev, 1960;Hughes, 1976;Turco et al., 1982;Zhuravlev et al., 1998;Vasilyev, 1998). For recent reviews see Farinella et al. (2001), Longo (2007), Svetsov and Shuvalov (2008), and Rubtsov (2009). ...
... From barometric and seismic recordings, Tunguska's main energy deposition was 3-50 Mt (most likely 10-15 Mt). The airburst occurred on a Tuesday morning at 7 h14 m a.m. ( ± 1 min) local time on June 17, 1908 in the Julian calendar, or at 0 h14 m UT on June 30, 1908 in today's Gregorian calendar (Farinella et al., 2001;Longo, 2007). The change to the Gregorian calendar was made in Russia not until 14 February 1918. ...
... Fires were also started in a spotty pattern over a larger area, out to about 10-15 km from the epicenter . Coincidentally, the epicenter of the airburst occurred just offset from the crater center of a lower Triassic Kulikovksy paleo-volcanic complex that is part of the Siberian igneous province associated with the Permian-Triassic extinction event (Longo, 2007). ...
The airburst events at Chelyabinsk and Tunguska in Russia are the best-documented asteroid impacts of recent times. Models that assess the potential danger from such events rely on an accurate picture of their aftermath. Here, we re-examine the most critical eyewitness accounts of the Tunguska airburst, namely those that describe injuries and casualties, and those that paint a picture of what events were responsible. Not all relevant information has survived in the written record and there are contradictions that create some ambiguity. We find that inside and near the tree-fall area were at least 30 people. Many lost consciousness and at least 3 passed away (immediately or later) as a direct consequence of the Tunguska event. The airburst created a butterfly-shaped pattern of glass damage extending 4–5 times wider than that seen at Chelyabinsk. At these larger distances, any injuries from falls, shattering glass cuts, or from UV radiation exposure were not reported.
... The 1908 Tunguska Event (TE) has attracted the scientific curiosity of many researchers for more than one century. After the earliest studies, it was evident that the 2150 km 2 wide devastation of the Siberian taigà was the result of the impact of a cosmic body with the Earth (see Vasilyev 1998, Longo 2007, and Artemieva and Shuvalov 2016 for reviews). However, there was a strong disagreement about its nature: comet or asteroid? ...
The 1908 June 30 Tunguska Event (TE) is one of the best studied cases of cosmic body impacting the Earth with global effects. However, still today, significant doubts are casted on the different proposed event reconstructions, because of shortage of reliable information and uncertainties of available data. In the present work, we would like to revisit the atmospheric fragmentation of the Tunguska Cosmic Body (TCB) by taking into account the possibility that a metre-sized fragment could cause the formation of the Lake Cheko, located at about 9 km NorthWest from the epicentre. We performed order-of-magnitude calculations by using the classical single-body theory for the atmospheric dynamics of comets/asteroids, with the addition of the fragmentation conditions by Foschini (2001). We calibrated the numerical model by using the data of the Chelyabinsk Event (CE) of 2013 February 15. Our work favours the hypothesis that the TCB could have been a rubble-pile asteroid composed by boulders with very different materials with different mechanical strengths, density, and porosity. Before the impact, a close encounter with the Earth stripped at least one boulder, which fell aside the main body and excavated the Lake Cheko. We exclude the hypothesis of a single compact asteroid ejecting a metre-sized fragment during, or shortly before, the airburst, because there is no suitable combination of boulder mass and lateral velocity.
... The Tunguska catastrophic blast 1908 in Siberia, which devastated an area of 2,150 km 2 knocking down some 80 million trees, is considered today by the majority of the scientific community as a result of a comet airburst (Kulik 1939;Longo et al. 1994Longo et al. , 2005Longo 2007). However, after 80 years of research, the nature and composition of the comet still remains mysterious, although in recent years the evidence of a comet airburst became more valuable, since traces of association of high-pressure carbon allotropes, diamond and lonsdaleite together with troilite, taenite, γ-Fe and schreibersite have been found in peat close to the Tunguska blast epicenter (Zlobin 2013;Kvasnytsya et al. 2013). ...
... A possible Tunguska impact scenario has been intensively discussed in Longo (2007). The most feasible explanation is to assume an extremely bright comet (bolide), "Tunguska Cosmic Body" entering the Earth"s atmosphere with 10-20km/s. ...
... The figure also includes a couple of estimates of the wind speed required to fell a given percentage of trees in a stand. Based on previous models and simulations burst energies of 3-30 Mt at altitudes of 5 to 15 km have been suggested by previous researchers, a summary of which is given in Longo (2007) or Artemieva and Shuvalov (2016). Despite its simplicity, the model in Fig. 5 roughly agrees with this range. ...
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 were used to calibrate a simple analytical model that can be used to quickly estimate the burst height of an incoming asteroid or comet.
The hydrocode simulations show both rocky asteroids and icy comets are plausible Tunguska meteors, over a wide range of sizes, speeds, entry angles, at least in terms of the energy delivered and height of burst required to produce the tree-fall, and the lack of an obvious impact crater on the ground. This agrees with previous analytical estimates and hydrocode simulations of hypothetical Tunguska meteors, and provides a complete range of possibilities.
Modelling of the tree wind resistance predicts windspeeds of 40–50 m/s are required to fell most of the trees. This is slower than previous estimates from nuclear test data, but faster than lower bound estimates from a 3 Mt blast. It suggests an energy of 10 Mt is most likely for Tunguska, but requires missing tree size distribution and wind response data to better narrow the probability distribution of potential Tunguska impactors.
... We take the size of typical pearls to be close to the critical point for collapse under their pressure against the assumed 10 MeV potential difference across the skin. Then, taking the dark matter density in our galaxy to be 3 GeV/m 3 , we estimate that the earth is hit by one of our pearls about once every 200 years, matching with the assumption that the famous Tunguska event [19] was caused by the fall of such a pearl [7]. An impact rate of one pearl per 200 years means that the earth should have been hit by 2 * 10 7 pearls in its history. ...
As a solution to the well-known problem that the shock wave potentially responsible for the explosion of a supernova actually tends to stall, we propose a new energy source arising from our model for dark matter. Our earlier model proposed that dark matter should consist of cm-large white dwarf-like objects kept together by a skin separating two different sorts of vacua. These dark matter balls or pearls will collect in the middle of any star throughout its lifetime. At some stage during the development of a supernova, the balls will begin to take in neutrons and then other surrounding material. By passing into a ball nucleons fall through a potential of order 10 MeV, causing a severe production of heat — of order 10 foe for a solar mass of material eaten by the balls. The temperature in the iron core will thereby be raised, splitting up the iron into smaller nuclei. This provides a mechanism for reviving the shock wave when it arrives and making the supernova explosion really occur. The onset of the heating due to the dark matter balls would at first stop the collapse of the supernova progenitor. This opens up the possibility of there being two collapses giving two neutrino outbursts, as apparently seen in the supernova SN1987A — one in Mont Blanc and one 4 h 43 min later in both IMB and Kamiokande.
... In 1908 a cosmic body is supposed to have fallen down in the Tunguska region of Siberia [1], where its explosion caused the trees to fall down in an area of 2000 km 2 . The cosmic body is commonly assumed to have been a comet or possibly a meteorite. ...
... The main point of the present article is now to discuss how these balls might be observed via their relatively smaller non-gravitational interactions. In fact we suggest that one of these balls hit the earth in Tunguska in 1908 causing the famous Tunguska event [1]. ...
It is suggested that the Tunguska event in June 1908 was due to a cm-large ball of a condensate of bound states of 6 top and 6 antitop quarks containing highly compressed ordinary matter. Such balls are supposed to make up the dark matter as we earlier proposed. The expected rate of impact of this kind of dark matter ball with the earth seems to crudely match a time scale of 200 years between the impacts. The main explosion of the Tunguska event is explained in our picture as material coming out from deep within the earth, where it has been heated and compressed by the ball penetrating to a depth of several thousand km. Thus the effect has some similarity with volcanic activity as suggested by Kundt. We discuss the possible identification of kimberlite pipes with earlier Tunguska-like events. A discussion of how the dark matter balls may have formed in the early universe is also given.
... Clear evidence of one or more impact craters or fragments from the impactor was, however, never found. This gave rise to several alternative hypotheses, although it is now agreed that the TE was caused by the explosion in the atmosphere, between 10 and 5 km above the ground, of an extraterrestrial object (Longo, 2007, and references therein), a comet or Fig. 1 Topographic map of the Tunguska region, showing: the devastated area (thick red line from Longo et al., 2005); the inferred epicentre of the TE (yellow circle; from Fast et al., 1976); the likely trajectory of the TCB (mod. from Gasperini et al., 2008); and the position of Lake Cheko, NW of the epicentre. ...
Several lines of evidence indicate that Cheko, a small lake close to the epicenter of the 1908 Tunguska Event (TE), fills a crater left behind by a fragment of the Tunguska Cosmic Body (TCB) that impacted the ground downrange of the main explosion. It is thought that over 80 million trees were flattened or burnt as a consequence of the TE. However, a small number of trees in the devastated area survived the explosion and recorded in their growth-ring patterns the environmental changes that followed this event. Some of those trees were found around Lake Cheko, ~10 km NW of the inferred TE epicenter. We analyzed new data from the floor of Lake Cheko, including seismic-reflection profiles, side-scan sonar and video images, as well as dendrochronological evidence in tree samples collected along the shores, to test the hypothesis of a 1908 formation of the lake.This article is protected by copyright. All rights reserved.
... Before that, the most famous witnessed impact was the Tunguska event in 1908, in which an asteroid or small comet exploded over a deserted region in Siberia. Such an explosion is capable of destroying a large metropolitan area 3 . Although the risk of collision between a NEO and Earth is extremely small, depending on the NEO size and impact point, the consequences could be catastrophic. ...
Near Earth Objects (NEOs) have periodically hit Earth throughout its history, and it is a fact that such impacts will continue to occur. Although the risk of serious collisions is extremely small, depending on the NEO size and impact point, the consequences could be catastrophic. Thanks to increased monitoring efforts, there is a high likelihood of spotting a NEO threat years in advance, potentially providing the opportunity for the international community to mitigate or even prevent the possible impact through timely actions. Being able to communicate these actions to the public, manage panic, and prepare for potential impact is critical. In September 2013, students and young professionals from around the world met in Beijing, China, for the annual Space Generation Congress (SGC). During SGC, the Society Working Group - sponsored by Secure World Foundation (SWF) and composed of 16 people from 10 different countries - discussed how the NEO threat could be best communicated to the public. Expanding upon the foundational work of UN Action Team 14 and SWF, the working group made several recommendations focused on defining an efficient communication and education plan, the role of the media, its benefits and dangers, and the necessary collaboration with emergency response officials and science communicators. This paper explores in detail these recommendations and categorizes them into temporal strategies - short, medium, and long term actions - depending on the estimated time of impact. With the long term strategy, the pre-impact timeline period is adequate for regional governments to produce local disaster management plans and coordinate education efforts with the media. With the medium term, while circulation of information is also important, these strategies prioritise the most critical issues while decision makers develop contingency plans based on proven disaster management methodologies. Finally, short term strategies rely on immediate actions to disseminate to the general public pre-existing natural calamity preparation and training information. We propose a "Mercalli-like" scale to be used for determining the impact effect and the respective actions to be taken to improve survivability. Recommendations also present practical and efficient educational programs to train and prepare the public and government for threats. The education proposal targets all parties involved providing at least a basic knowledge about the NEO threat, and attempts to explain the concept of impact prediction uncertainty, and how to communicate it in the appropriate context. We suggest using case studies to provide examples of the application of the communication and education programs proposed. Copyright ©2014 by the International Astronautical Federation. All rights reserved.
... The origin of the Tunguska blast was explained by a huge meteorite impact (e.g. Yavnel, 1957;Florensky, 1963;Longo et al., 1994;Serra et al., 1994;Longo, 2007;Gasperini et al., 2007Gasperini et al., , 2009Badyukov et al., 2011) or by a comet (e.g. Florensky et al., 1968aFlorensky et al., , 1968bGolenetsky et al., 1977;Ganapathy, 1983;Zbik, 1984;Nazarov et al., 1990;Hou et al., 1998;Kolesnikov et al., 1999Kolesnikov et al., , 2003Kolesnikov et al., , 2005Rasmussen et al., 1999;Gladysheva, 2007), or by a cosmic body. ...
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