Gladysheva, O.G. Tunguska Phenomenon: Discharge Processes near the Earth’s Surface. // Geomagnetism and Aeronomy 53(5). 672–676. 2013. doi: 10.1134/S0016793213050071
An investigation of the Tunguska cosmic body’s epicenter showed that both dried trees and those that survived the catastrophe are marked with characteristic deteriorations. For the trees that survived near the epicenter (the distance is <4 km), cracks of up to 7 m in length are found on their stems. All the vegetation near the explosion epicenter has traces of uniform scorch that covered the trees even on the land parts isolated by water. On the background of this uniform scorch, a notable feature is carbonization that touched the tree tops and the earthdirected ends of broken branches. All tops of both living and dried trees in the central zone are burned and dead. Carbonization of tops and branch ends was observed up to a distance of 10–15 km from the epicenter; i.e., charge processes took place over an area of more than 500 km2 in size. Carbonized branch ends have a characteristic “bird’s nail” shape, which has no analogs on the Earth. Similar deterioration is typical for the crater shape that obtains an anode during arc discharge combustion. It is supposed that the duration of these charge processes could be ≥1 min.