The Slano Blato Landslide (sl|plaz Slano blato), or the Salt Mud Slide, is a periodic landslide in Slovenia that is triggered approximately once a century.[1] Although around 8,000 active landslides are present in Slovenia, the Slano Blato Landslide stands out as one of the most serious in terms of the damage it has caused.[2]
The landslide is located on the southern edge of the Trnovo Plateau of the Dinaric Alps, below Mount Čaven and Little Mountain (Slovenian: Mala gora) next to the Platna mountain pasture.[3] It is moving along Grajšček Creek (which also originates in the landslide itself[4]) toward the settlement of Lokavec near Ajdovščina.[1] It is 1010to long and 60mto250mm (200feetto820feetm) wide, covering approximately between the elevations of 360mand660mm (1,180feetand2,170feetm).[1] [5] Its maximum flow rate was recorded at 100m (300feet)/day.[1]
The name of the landslide area was recorded as Blatna ('muddy') in 1881.[1] The origin of the designation 'salt(y)' (Slovene slan) is uncertain. A local folk belief states that the high cleanup cost of the landslide resulted in an exorbitant cost (cf. Slovene zasoliti 'to over-salt'; metaphorically, 'to charge excessively'). However, the landslide bore the designation 'salt(y)' before any cleanup efforts were ever made.[1] [6]
Other locals state that sheep used to wander down to the area from nearby pastures, where they would lick the mud as a natural salt lick. This basis for the name's origin is supported by the fact that chemical analysis of the water at the landslide has shown it to have a very high mineral content, including sodium sulfate, also known as Glauber's salt.[1] [7]
Oral tradition regarding the landslide goes back four centuries, connecting it to the construction of a small church dedicated to Saint Urban on the slope of Mount Čaven above Lokavec and below the landslide. Saint Urban was invoked as a protector against natural disasters, and particularly with regard to a lake that people believed was hidden inside Mount Čaven that threatened to flood the valley.[7] [8]
A 1789 source by Belsazar Hacquet mentioned the landslide, describing its debris flow in 1786.[7] It was described again in an 1887 report[9] that discussed the landslide event of 20 October 1885, in which 30 m of the road from Ajdovščina to Gorizia was destroyed.[7] Cleanup efforts and landslide mitigation measures were carried out by Austrian authorities in 1903.[1] [10]
In November 2000, heavy rain and warm weather triggered the Slano Blato Landslide, which buried about 15hectare of grassland and forest.[1] A secondary flow was triggered in September 2001.[7] The landslide stopped moving after this and is currently considered stable.[2] Following these events, an access road was built and 230000m2 of material was removed from the lower part of the landslide and deposited north of the Ajdovščina Airport.[7]