Gemmi Fault

[1] The western and central Swiss Alps are the fastest rising region of the country, with uplift rates of 1.5 millimetres per year (0.059 in/year) reached near Brig.

[2] A number of recently active fault systems have been identified in the Western Alps, but they often show only subtle signs of movement.

It is characterized by a conspicuous, up to 3 metres (9.8 ft) high offset in the landscape[3] between the Daubensee northeast of the fault and the Daubenhorn southwest of it.

[4] The fault lies at the bottom of a valley at Gemmi Pass (close to Leukerbad, Valais) between 1,800–2,700 metres (5,900–8,900 ft) elevation.

It cuts through carbonates, sandstones and shales of the Helvetic nappes; the rocks are of Jurassic-Eocene age and were folded during the Oligocene-Miocene.

Hot springs at Leukerbad and a Tertiary dyke at the Trubelstock close to the fault indicate elevated geothermal gradients in the ground.