11 September, 1881: The landslide of Elm: An artificial disaster

The locals and inhabitants of the small Swiss village of Elm for centuries had mined the nearby Tschingelberg for schist-plates, appreciated for its use in construction of buildings.
The introduction of obligatory public school in the mid of the 19th century in the Canton Glarus increased exponentially the demand of schist plates to be used in the school classes.
In the year 1861 to 1878 the mining activity at the Tschingelberg was carried out by privates, then the administration of Elm take over the lucrative business. In the following years 200m above (1.200m a.s.l.) the village a quarry in form of a semi open tunnel of 180m length and 65m depth was excavated.
With proceeding mining activity, the rock mass of the entire mountain slope lost its support, so during the year's minor rock fall events occurred and in the schist parallel fissures opened.
In 1876 above the quarry, at 1.550m height, a crack opened, until summer 1881 the fissure growth reaching a broadness of 2 to 3m, isolating a piece of the slope of 400m diameter from the mountain. Still the quarrying with explosives, causing strong vibrations in the mountain, continued.

The period from August 25. to September 10. 1881 was rainy with strong precipitations. The area around the quarry showed opening fissures, and many minor rock falls were frequent, on September 8. a large rock fall nearby the quarry occurred, subsequently the quarry was closed and on September 9. nearby houses evacuated.
The authorities of the local administration visited September 10. the area, but didn't consider the situation threatening to the village.

Fig.1. The landslide of Elm, figure from Geographisches Lexikon der Schweiz (1902-1910).

Small rock fall events occurred then continuously from September 10 to 11.
From the final rock fall that destroyed Elm we have a detail rich eyewitness report by a teacher of Elm, named Wyss:

"At afternoon 4 o'clock I stood, with the pocket clock in my left hand, on the open window observing carefully the movements of the mountain. Continuously smaller portions felt of from above, from the middle and from below, the uppermost fir row of the forest began to move backwards into the fissure.
The first greater fall occurred at exactly 5 o'clock and 15 minutes; the rock masses felt into the valley at the speed of a flash. They covered the schist mine, the with the tools and with the schist filled huts [...] the inn to the Martinsloch, evacuated by the inhabitants two days before. Also the beds of the Tschingel- and Ramin-river were raised.

The second, even larger rock fall occurred 17 minutes later, at 5 o'clock and 32 minutes, rushing with high speed above the earlier rock mass deposits.

Again 4 minutes later the third rock fall occurred. The enormous mass flowed through the air. The earth surface shakes; I run out from the house and followed the street. After 20 passes the houses behind me felt down. I estimate, according with other credible eyewitnesses, that the rock masses in 2 to 3 minutes reached the end position, where it now lays."

The rock fall killed 115 peoples and only 24 to 31 horribly mangled bodies were recovered - and from these only 13 could be identified by the cloths that they were wearing.

Fig.2. Map of the landslide of Elm, figure from Geographisches Lexikon der Schweiz (1902-1910). Note the parallel ridges on the landslide deposits remembering flow structures.

The rock fall of Elm is notable because of the eyewitnesses reports describing the movement like "a flow" of incredible speed, flowing above (and even in the air) the plain ground and upwards the slopes. This particular behaviour of rock fall propagation is still today poorly understood and one of the most intriguing features of mass movements.

Bibliography:

HÖFLER, H. & WITT, G. (2010): Katastrophen am Berg - Tragödien der Alpingeschichte. Bruckmann Verlag: 144

Online Resources:

Varia (1902-1910): Geographisches Lexikon der SCHWEIZ, 1902-1910. Verlag von Gebrüder Attinger, Neuenburg, 1902-1910; 1. Band: Aa - Emmengruppe: 695