Misplaced Pages

#411588

30-494: The lake was created by a giant landslide and is fed through a series of mountain creeks and drains underground. The water then resurfaces as the Oeschibach . Part of it is captured for electricity production and as a water supply for Kandersteg. In observations from 1931 to 1965, the elevation of the lake surface varied between 1,566.09 metres (5,138.1 ft) and 1,581.9 metres (5,190 ft). The average seasonal variation

60-525: A box-shaped depression, whose western headwall reaches 0.5 kilometres (0.31 mi) height while the eastern one is less conspicuous. At Kandersteg, the landslide debris forms the Uf der Höh hill, which is cut by secondary scarps, and which formed when the landslide hit the opposite valley flanks. The debris deposit is formed by large blocks up to several metres wide, with spaces often filled in by later soils. The terrain features hummocks and ridges perpendicular to

90-581: A flood from the lake in 1846 AD may have been caused by an unobserved landslide. The headwalls of the Kandertal landslide are still unstable. In summer 2018 a volume of 0.02 cubic kilometres (0.0048 cu mi) in the "Bim Spitze Stei" area between the Kandertal and Oeschinensee landslide detachment areas became noticeably unstable. Geophysical analyses have shown that there are a number of rock masses in motion, some of them containing warm permafrost , with most motion occurring in summer. As of 2021 ,

120-472: A length of 12 kilometres (7.5 mi) to just north of Reckenthal. It dammed the Kander River , generating a lake in the area of present-day Kandersteg which broke 200–300 years after the landslide and generated an outburst flood and debris flow, redepositing landslide debris as far as Frutigen . A more recent interpretation in 2020 is that no lake was formed. It is possible that winds generated by

150-496: A standard bit. This is the reason that diamond-tipped core drills are commonly used in construction to create holes for pipes, manholes, and other large-diameter penetrations in concrete or stone . Core drills are used frequently in mineral exploration where the drill string may be several hundred to several thousand feet in length. The core samples are recovered and examined by geologists for mineral percentages and stratigraphic contact points. This gives exploration companies

180-806: A time where a change on climate and an expansion of glaciers in the area of the landslide was taking place. Lake sediments indicate the occurrence of a large earthquake about 3,300 years ago, which, while not necessarily directly causing the landslide, may have destabilized the slopes that later failed. While the Oeschinensee collapse was once considered to have been contemporaneous with the Kandertal avalanche, research published in 2018 indicates that it actually occurred only 2,300±1,200 years ago. The landslide took place just before historical times in Switzerland, but sediments in lakes have shown evidence of earthquakes during that time that could have caused

210-418: Is more successful when cutting through rebar. The earliest core drills were those used by the ancient Egyptians , invented in 3000 BC. Core drills are used for many applications, either where the core needs to be preserved (the drilling apparatus used in obtaining a core sample is often referred to as a corer), or where drilling can be done more rapidly since much less material needs to be removed than with

240-691: Is now part of the Jungfrau-Aletsch protected area . Climate variations can cause slope instabilities and with global warming scientific interest in large collapses of mountains has risen. Giant landslides in the Alps are commonly related to the destabilizing effects of ice retreat at the end of the ice ages, but the landslides often occur millennia after the retreat of ice, suggesting that additional triggers such as climate variations and earthquake activity - perhaps in turn caused by deglaciation - are necessary to actually cause collapses. Oeschinensee

270-487: Is possible that the earlier landslide left an earlier lake or swamp. Lake sediments in Oeschinen Lake show evidence of turbidites , some of which could be related to collapses caused by earthquakes. A number of collapse scarps lie on the mountains surrounding the lake and could have been the source of landslides. At least six such collapses took place. Some of the collapses may have occurred in historical times;

300-581: Is situated in the Bernese Alps , within a 5 kilometres (3.1 mi) long side valley of the Kandertal, and lies at about 1,578 metres (5,177 ft) elevation. It receives inflow from glaciers and springs, while its waters eventually seep through landslide debris although in the past (before a small dam was built) the lake periodically overflowed. The mountains are largely formed by various formations of Mesozoic rocks, which are mostly limestones with marls and sandstones ; their layered structure and

330-458: The Holocene . Both the number and timing of landslides is controversial, with the most recent estimates stating that the large Kander landslide occurred about 3,210 years ago and the smaller Oeschinen Lake landslide 2,300 years ago. Both may have been caused by earthquakes, and the latter landslide generated the Oeschinen Lake. More recent landslides have occurred, and unstable rock masses occur in

SECTION 10

#1732780456412

360-508: The Kandertal event). The slide crossed the Oeschinen valley and ran up the opposite slope and down the valley. After about one minute the collapse was complete. The landslide left a conspicuous slide surface bordered by high cliffs. These cliffs reach heights of 80 metres (260 ft); the highest point lies at 2,250 metres (7,380 ft) elevation. Debris from the landslide covers an area of 1.1 square kilometres (0.42 sq mi) at

390-423: The Oeschinensee landslide was considered a single event. The increased instability observed in summer 2018 led to an investigation of the detachment area, with drilling , satellite mapping and the installation of telemetry devices among other responses. Drill core A modern core drill is a drill specifically designed to remove a cylinder of material, much like a hole saw . The material left inside

420-481: The collapse occurred over a timespan of about two minutes, and the debris first descended into the Kander valley and then proceeded northwards. The emplacement would have taken about ten minutes. During its later stages, the northern part of the landslide incorporated wet sediments from the Kander valley and began to collapse, forming extensional features such as the ridges at Blausee. The Fisistock collapse area forms

450-492: The collapse. While glacial erosion that undercuts valley slopes is necessary to cause landslides, often additional triggers such as earthquakes are necessary to actually trigger the collapse. It detached from the northwestern flank of the Doldenhorn mountain, reached the valley floor after about 20 seconds with a speed of about 65 metres (213 ft), where it was deflected by an earlier landslide deposit (probably from

480-433: The core, then re-inserted to drill deeper, and repeated. Removing all the rods every 30 feet to recover the core was time consuming for deep holes required for mining and mineral exploration, some of which may be 1,000 ft deep or more. This method greatly reduced the time required to drill a hole, and thus its cost, which increased the use of drilling and decreased the use of shaft sinking as a means of mineral exploration. It

510-433: The drill bit is referred to as the core . Core drills used in metal are called annular cutters . Core drills used for concrete and hard rock generally use industrial diamond grit as the abrasive material and may be electrical, pneumatic or hydraulic powered. Core drills are commonly water cooled, and the water also carries away the fine waste as a slurry. For drilling masonry, carbide core drills can be used, but diamond

540-574: The information necessary to begin or abandon mining operations in a particular area. Before the start of World War Two, John Branner Newsom, a California mining engineer, invented and patented a core drill that could take out large diameter cores (>5 ft.) up to 10 feet in length for mining shafts. This type of shaft-sinking drill is no longer in use as it was cumbersome, prone to jamming with cuttings, thus slow compared to conventional shaft sinking techniques, and only worked effectively in soft rock formations. Modern shaft-sinking technology accomplishes

570-655: The lake. Since 2007 the lake has been part of the Jungfrau - Aletsch - Bietschhorn UNESCO World Heritage Site . As of summer 2021, a circumnavigation of Lake Oeschinen is not possible. The reason for this is the danger of an imminent rockfall on the south shore, which is why paths are closed there. This article related to a lake in the canton of Bern is a stub . You can help Misplaced Pages by expanding it . Oeschinensee and Kandertal landslides The area of Oeschinen Lake and Kander river valley in Switzerland have been subject of multiple large landslides during

600-577: The landslide area. Large landslides that block entire valleys are a considerable hazard in mountainous regions, in particular when they form highly unstable dams on rivers; the breach of such a dam on the Dadu River in China in 1786 caused a flood that killed 100,000 people. On the other hand, such landslides can generate spectacular landscapes, such as the glaciated terrain around Oeschinen Lake in Switzerland which has drawn tourists since 150 years and

630-548: The landslide blew down forests, and sparks from moving rocks ignited wildfires . With a surface area of 10 square kilometres (3.9 sq mi) and a volume of 0.8 cubic kilometres (0.19 cu mi) is one of the largest landslides in the Alps . and detached from the north-northwestern flanks of the Fisistock mountain, with an additional collapse from Bire Mountain north of Fisistock. Computer simulations indicate that

SECTION 20

#1732780456412

660-438: The outlet of Oeschinensee and may extend below the lake surface. The deposits feature large boulders and hummocky topography. How the landscape looked like before the collapse is unclear but a volume of 0.046 cubic kilometres (0.011 cu mi) has been estimated on the basis of plausible reconstructions both of the source area and the landslide deposit. The landslide blocked the valley and created Oeschinen Lake, although it

690-456: The same faster and at a much cheaper cost. Core drills come with several power choices including electric, pneumatic, and hydraulic (all of which require power sources, such as a generator). Wireline core drilling is a technique used to extract the core without having to retrieve the entire drill string of rods, which generally only needs to be retracted when the hole is finished or the drill bit must be replaced. Drill rod extensions are added at

720-599: The slide direction. Some groundwater -fed lakes such as Blausee lie within the debris deposit. Undulating terrain at the end of the landslide deposit suggest that it behaved like a fluid there. The Kandertal landslide was originally interpreted to have occurred 9,600 years ago, at a time where numerous giant landslides happened in the Austrian and Swiss Alps and a possibly earthquake -related group of landslides south of Kandersteg. More recent research in 2020 however implies that it actually occurred 3,210±220 years ago, at

750-506: The speed of the motion has increased with every year. There are a number of scenarios for a future collapse of the Spitze Stei. Most of them would spare the Oeschinen lake and Kandersteg, but buildings close to the lake would be in danger. Landslides could dam local creeks and generate mudflows that can reach Kandersteg. As a consequence, the area below the Oeschinensee landslide scar has been closed off and dry dams were built above

780-422: The top as required to extend the string as the hole gets deeper. The core sample is carried by an inner tube locked in place in contact with the drilling head, To recover the core, the drive system is disconnected, opening the top of the uppermost drill rod. A tool called an overshot assembly is lowered at the end of a wire and pumped down the string with water pressure. When it reaches the sample tube, it locks onto

810-446: The top, and using the retraction winch to apply tension to the wire unlocks the sample tube from the drill head and retracts it and the core sample within it to the open top end of the drill string, where it can be removed before returning the sample tube down the drill string to lock back onto the cutting head. This is particularly useful for drill holes more than 30 ft deep as otherwise the whole string of rods had to be removed to recover

840-449: The village in 2021. The landslide deposits were originally interpreted as glacial deposits, before outcrops investigated during the construction of railroads led to the discovery of the Kandertal landslide in 1897 or 1909. Over the 20th and 21st century, different estimates on the number, ages, causes and volumes of the landslide deposits have been made. A major source of uncertainty is how to separate distinct landslide deposits; usually,

870-571: The weakness of the marl layers facilitates the development of landslides. The seismically active Rawil depression is only about 20 kilometres (12 mi) southeast of the Kander area. Multiple landslides and collapses have occurred in the Oeschinen area, including the Kandertal and Oeschinensee collapses; both landslides left debris at the outlet of the Oeschinensee. Apart from the two large landslides, avalanches, rockfalls and debris flows have left smaller deposits. A pre-Kandertal landslide has been identified in drill cores . The landslide ran over

900-440: Was 12.2 metres (40 ft) (September/April). The lake is generally frozen for five months, from December to May. From time to time ice skating is possible on the ice. Fish in the lake include Arctic char ( Seesaibling ), lake trout ( Kanadische Seeforelle ), and rainbow trout ( Regenbogenforelle ). From January to March, ice fishing is popular. A gondola lift from Kandersteg leads to Oeschinen, 25 minutes by foot from

#411588