Skred som følge av bombeangrep ved Gunneklevfjorden 1943.

Abstract

On the 24th of July 1943 an allied bomb raid took place in order to destroy the factories near Porsgrunn. By this event a settlement of small dwelling houses on the flat shore of Gunneklevfjord was hit by bombs. The ground is clay. 50 bombs of 500 Lbs weight fell over an area of 50 000 sq.m, causing an artificial clay-slide, in its effect completely similar to a natural one. The detonations of the bombs softened the underground, and sliding slowly towards the fjord the firm upper crust broke into flakes. Swimming on the semi-liquid substratum flakes collided in some places, forming a ridge at their contact. In other places crevices were formed between two flakes, where the soft clay from the underground was pressed up. In the shallow fjord the bottom outside the slipped area rose to above sea level. 10 or 12 wooden villas lay within the area, each surrounded by a garden. These houses were completely wasted by the disturbance in the ground. Their foundations broke up, and in some of them the walls and roof fell down. During the bomb raid 50 persons had taken refuge in the cellars. Curiously not one of them was seriously wounded, as the soft clay contained no firm earth-lumps or stones to be blasted about from the craters.