Engadine Line
The Engadine Line is an over 50-kilometre (30 mi) long strike-slip fault in the Swiss canton of Graubünden, which extends into Italy and Austria.
It began in the Oligocene, but there is evidence of recent neotectonic activity, which resulted in the collapse of the Maloja Pass area at the beginning of the Holocene.
[7] The towns of Bever, Maloja, Nauders, S-chanf, Samedan, Sils, St. Moritz, Vicosoprano and Zernez are located along the Engadine Line,[8] as is the Albigna Dam.
[9] The fault trace is generally not recognizable on the surface, as it is buried beneath alluvium; the only outcrops are found at Maloja[10] and at Stragliavita close to Zernez.
[11] Parts of the Engadine Line were already recognized by 1914, but it was only in 1977 that they were identified as belonging to a single fault zone,[12] reportedly after a suggestion by a Chinese geologist.
[16] The movement on the Engadine Line is part of a larger tectonic process in the Alps, whereby the mountain range is compressed in north-south direction and is thus squeezed upwards and eastwards.
[31] The Inntal fault is probably the northeastern continuation of the Engadine Line[32] and has a maximum offset of 48 kilometres (30 mi), reaching the Molasse basin.
Depressions located between the fault traces are occupied by lakes such as Silsersee, Silvaplanersee and St. Moritzsee, which do not appear to be moraine-dammed[45] and may have been formed by the activity of the Engadine Line.
[22] There, the Engadine Line runs along the southern side of the Inn and Bregaglia Valleys and is accompanied by deep-seated mass failures; eventually it disappears under sediments[47] close to Promontogno.
[10] Slope instability that causes frequent landslides[52] and deformation in rock formations of the Bregaglia Valley may related to activity of the Engadine Line.
[54] Alps portal Movement along the Engadine Line commenced during or before the late Oligocene[55] but post-dates the cooling of the Bergell pluton 28 million years ago.
[4] Movement took place during the Oligocene[56] before probably ceasing during the Miocene[57] and has been attributed to the so-called "Turba phase" of extensional development of the Alps.
[58] The movement along the Engadine Line and Inntal faults influenced the course of the Inn River,[55][59] allowed its watershed to expand southwestwards,[60] and altered drainages during the Sarmatian.
[23] The "beheading" of the Inn Valley at Maloja Pass, which took place between 29,400–14,500 years before present,[48] is one of the major geologic events in the Quaternary of this sector of the Alps.
Tectonic stresses exercised by movements along the Engadine Line may have caused the collapse,[72] which left a steep escarpment at Maloja Pass and a large elevation difference between the Inn and Bregaglia valleys.
[81] In the Ötz River valley in Austria, the Engadine Line and the Inntal fault have been related to increased earthquake activity, which may explain the occurrence of frequent landslides in the area.
[82] Research published in 1979 indicated that earthquakes on the Engadine Line might reach a maximum magnitude of M 5.5[14] or 6.9 with a break length of 40 ± 10 kilometres (24.9 ± 6.2 mi).
[63] In the Scuol-Tarasp area, mineral water and carbon dioxide rise to the surface (the latter forming mofettes)[84] along the Engadine Line and its intersection with more local geologic lineaments.
