Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20 th century. These reliefs consist of several tens (up to hundreds) of stripes that have arisen as a result of the destruction of vegetation and the surface layer of the ground. Structures of stripes are extended, ranging in size from 6 km to ≥20 km, with a width of several kilometers. Every strip (scratch on the ground) is roughly estimated to be up to 50 m wide and ≥500 m long. The stripes start from one edge of the relief and stretch at inter-vals to the other, slightly diverging symmetrically from the central axis. It was determined that these reliefs are not associated with the movement of soil (avalanches, mudflows) or with the impact of air currents (hurricanes, storm, tornado). Geographically, these struc-tures of stripes are located within a circle with a radius of 770 km, described around the epicenter of the Tunguska catastrophe.
Reliefs on the Earth’s surface, the configuration of which is difficult to explain by the influence of known natural forces were discovered by A. P. Lopatin and L. M. Uskova [
The given reliefs show a specific destruction of the surface layer of the ground and woody vegetation in territories tens of kilometers long and several kilometers wide. On the archival images of the Google Earth Service, one can see a fan-shaped pattern consisting of stripes that resemble scratches in appearance against the general green background of the taiga. The stripes differ from the surrounding area covered with coniferous forests in the color of the image. The stripes range in color from white to reddish, most likely due to soil and topsoil removal; the color is determined by the color of the underlying rock. The stripes are not parallel; they tend to deviate symmetrically from the central axis of the structure.
These reliefs on the earth’s surface were clearly visible in the photographs of the late twentieth century. Clearings (glades) predominated on them at that time and young small-leaf and shrub growth were developed [
At present, according to V. V. Burmakin, it is proposed that more than 30 reliefs be attributed to these so-called Siberian fans. Only 15 of the most characteristic reliefs will be considered in this work to determine the features of their shape and location.
The Kasskoye formation has a maximum length of about 23 km with a maximum width of about 4 km. As you can see in
The Kazhma formation is traced over 17 km in length (
This formation located between the Lendakha River and the Big Pit River (
The formation located near the Sedelochny stream is shown in
All the structures of stripes considered above have an elongated shape, to one degree or another, close to an ellipse. The maximum size of these formations can be defined as the central axis. Rays (stripes or scratches) fan out along this entire axis, starting at one end, which can be defined as the initial zone. In some structures, diverging stripes are traced from the initial zone along the entire length of the formation; in others, stripes diverge from different parts of the central axis. According to rough estimates, the width of the stripes can reach 50 m with a length of ≥500 m. It should be noted that according to the height profiles in Figures 1-4, the terrain both decreases and increases as we move away from the initial zone along the central axis.
An azimuth was determined for each structure of stripes. It is the angle between the geographic meridian (northward direction) and the central axis (away from the initial zone). Coordinates of the formations and its azimuths are given in
As you can see in
| No. | Formation | Coordinates | Azimuth* |
|---|---|---|---|
| 001 | Kazhma | 59˚36'48.96"N; 96˚05'30.90"E | 69˚ ± 5˚ |
| 002 | Lendakha—Big Pit | 59˚05'42.94"N; 93˚10'52.91"E | 113˚ ± 7˚ |
| 003 | Kasskoye | 59˚23'30.68"N; 90˚12'49.37"E | 116˚ ± 5˚ |
| 004 | Sym2 | 60˚07'29.92"N; 89˚53'08.12"E | 92˚ ± 8˚ |
| 005 | Sym3 | 60˚09'40.18"N; 90˚12'41.82"E | 86˚ ± 4˚ |
| 006 | Sym | 60˚09'19.29"N; 90˚03'32.77"E | 80˚ ± 7˚ |
| 007 | Sedelochny | 55˚00'03.56"N; 96˚19'03.08"E | 85˚ ± 5˚ |
| 008 | Agul-Chukhlaikha | 54˚54'16.52"N; 96˚40'50.78"E | 50˚ ± 20˚ |
| 009 | Tumanshet | 54˚57'31.20"N; 96˚51'53.52"E | 103˚ ± 7˚ |
| 010 | Right bank of the Lena river | 58˚46'09.96"N; 111˚20'00.67"E | 37˚ ± 5˚ |
| 011 | Lena river1 | 58˚39'00.54"N; 110˚47'45.66"E | 15˚ ± 20˚ |
| 012 | Lena river2 | 56˚27'02.25"N; 106˚42'40.99"E | 4˚ ± 10˚ |
| 013 | B. Vereya—Ilim | 55˚59'00.11"N; 104˚44'41.86"E | 12˚ ± 5˚ |
| 014 | Gorely-Kelora-Lena | 54˚51'04.75"N; 106˚19'40.78"E | 100˚ ± 7˚ |
| 015 | Kulebyachikha-Lena River | 57˚41'26.48"N; 108˚01'24.31"E | 55˚ ± 10˚ |
*The last column is the angle between the direction of the central axis of the structure and the direction to the north.
The azimuth of the location of Siberian fan reliefs on the ground varies in the range from 4˚ to 116˚. If for the eastern points (010, 011, 012 and 013) the direction of the central axis is close to the north direction, then the western structures of the stripes (002, 003, 004 and 005) are stretched to the east.
Specific formations called Siberian fan reliefs were discovered in the airborne photographs in the 1970s-1990s. The images were taken from heights from ~4 km to ~30 km. Siberian fan reliefs are structures elongated in one direction of stripes or scratches on the surface of the Earth. The size of such formations is from 6 km to ≥20 km. Divergent stripes, as a rule, extended symmetrically, starting at one end of the structure, along the entire length of the object. The stripes are discontinuous; their width can reach 50 m with a length of more than 500 m.
The sites on which the reliefs were found are located in a wide range of heights from an altitude of tens of meters above sea level to an altitude of over 900 m. Geographically, all 15 structures considered in this work are in the range from ~55˚ to ~60˚ north latitude and between ~90˚ and ~108˚ east longitude. The direction of the central axis of the diverging bands varies from north to east-south-east.
What could be the reason for the formation of such structures of stripes? According to the height profiles in Figures 1-4, the relief of the terrain both decreases and increases with distance from the initial zone along the central axis. So, for example, the drawing of the Kazhma structure (
Storms, hurricanes and other wind processes in these latitudes, as a rule, do not lead to stripe demolition of turf and woody vegetation. Moreover, in
angle of the directions of the stripes exceeds 100˚. It is unlikely that the movement of air masses could be so multidirectional at the same time.
The sound and light effects of the Tunguska catastrophe were noted by local residents at distances of many hundreds of kilometers from the epicenter [
Thus, at present, the reason for the formation of Siberian fan reliefs, as well as the time of their appearance on the Earth’s surface, require further careful study.
The authors thank Valery Vitalievich Burmakin for the archival photographs he kindly provided.
The authors declare no conflicts of interest regarding the publication of this paper.