| Illgraben | |
|---|---|
 Illgraben, seen from the Illhorn | |
| Floor elevation | 830 m (2,720 ft) |
| Length | 4 km (2.5 mi) |
| Area | 9 km2 (3.5 sq mi) |
| Geography | |
| Country | Switzerland |
| State | Valais |
| Coordinates | 46°16′54″N7°36′51″E / 46.28159°N 7.61419°E |
| River | Illbach |
The Illgraben valley is one of the most geologically unstable regions of Switzerland, and is located south of Leuk in the Canton of Valais.
The valley consists of triassic dolomite, porous limestone and quartzite, [1] and due to intense weathering, the valley is well-known among geologists as a place to study processes like erosion, rockfall, debris and mud flows. Likewise, the Illgraben serves as a laboratory to test mudflow warning systems. The Swiss Federal Institute for Forest, Snow and Landscape Research uses radars, microphones and cameras to register mudflow events, and to warn the population of Leuk. [2] Due to the geology, mudflows occur two to three times a year, while places threatened by mudflows usually experience only one every 30 to 40 years. [1]
Several times a year, the Illgraben's mud flows cause the Rhône river to turn murky until it reaches Lake Geneva, which is 90 kilometers (56 miles) downriver. The Pfynwald (French: bois de Finges or forêt de Finges), a natural reserve and one of the largest continuous Scots pine forests of Europe, is located on the alluvial cone of Illgraben's stream, the Illbach. [3] The Pfynwald itself is an important center for ecological studies.[ citation needed ]
A north-easterly view into the Illgraben is possible from the hiking path Chandolin - Plaine Madeleine. [4] From Susten (650 m,part of Leuk), hikers will first encounter the Bhutan bridge, a 134 meter suspension bridge, before seeing the valley's interior. From there, there is an unmarked trail to the Steinschlaghütte (English: rock fall hut), or to the alpine lake Illsee and the Illhorn.[ citation needed ]
Video documents by the Swiss Federal Institute for Forest, Snow and Landscape Research:
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, shallow or deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides.
The river Ticino is the most important perennial left-bank tributary of the Po. It has given its name to the Swiss canton through which its upper portion flows.
Valais, more formally the Canton of Valais, is one of the 26 cantons forming the Swiss Confederation. It is composed of thirteen districts and its capital and largest city is Sion. The flag of the canton is made of thirteen stars representing the districts, on a white-red background.
A lahar is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley.
Nevado del Ruiz, also known as La Mesa de Herveo is a volcano on the border of the departments of Caldas and Tolima in Colombia, about 129 km (80 mi) west of the capital city Bogotá. It is a stratovolcano composed of many layers of lava alternating with hardened volcanic ash and other pyroclastic rocks. Volcanic activity at Nevado del Ruiz began about two million years ago, since the Early Pleistocene or Late Pliocene, with three major eruptive periods. The current volcanic cone formed during the present eruptive period, which began 150,000 years ago.
A geologic hazard or geohazard is an adverse geologic condition capable of causing widespread damage or loss of property and life. These hazards are geological and environmental conditions and involve long-term or short-term geological processes. Geohazards can be relatively small features, but they can also attain huge dimensions and affect local and regional socio-economics to a large extent.
Monte Rosa is a mountain massif in the eastern part of the Pennine Alps, on the border between Italy and Switzerland (Valais). The highest peak of the massif, amongst several peaks of over 4.000 m, is the Dufourspitze, the second highest mountain in the Alps and western Europe, after Mont Blanc. The east face of the Monte Rosa towards Italy has a height of about 2.400 meters and is the highest mountain wall of the Alps.
A mudflow, also known as mudslide or mud flow, is a form of mass wasting involving fast-moving flow of debris and dirt that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/second. Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows, allowing them to travel farther and across lower slope angles. Both types of flow are generally mixtures of particles with a wide range of sizes, which typically become sorted by size upon deposition.
Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally have bulk densities comparable to those of rock avalanches and other types of landslides, but owing to widespread sediment liquefaction caused by high pore-fluid pressures, they can flow almost as fluidly as water. Debris flows descending steep channels commonly attain speeds that surpass 10 m/s (36 km/h), although some large flows can reach speeds that are much greater. Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide. The largest prehistoric flows have had volumes exceeding 1 billion cubic meters. As a result of their high sediment concentrations and mobility, debris flows can be very destructive.
The Mud Creek Glacier is the southernmost glacier on Mount Shasta in the U.S. state of California. It lies to the east of Sargents Ridge on Shastarama point near 10,915 feet (3,327 m) above sea level. The glacier is smaller than the northern ones on Mount Shasta such as Whitney, Hotlum, Bolam, and Wintun Glaciers. There are approximately 80 glaciers in California and unlike the glaciers in Alaska, Colorado and Montana. California’s existing current glaciers are not remnants of the Pleistocene, but instead relatively young approximately 1,000 years in age. The Mud Creek Glacier is one of at least 7 recognized glaciers on Mt. Shasta by the United States Geological Survey (USGS) the rest being: Whitney, Hotlum, Bolam, Wintun, Konwakiton, and Watkins.
Burned area emergency response (BAER) is an emergency risk management reaction to post wildfire conditions that pose risks to human life and property or could further destabilize or degrade the burned lands. Even though wildfires are natural events, the presence of people and man-made structures in and adjacent to the burned area frequently requires continued emergency risk management actions. High severity wildfires pose a continuing flood, debris flow and mudflow risk to people living within and downstream from a burned watershed as well as a potential loss of desirable watershed values.
The Val d'Anniviers is a Swiss Alpine valley, situated in the district of Sierre in Valais, which extends south of the Rhône Valley, on the northern slopes of the Pennine Alps. The valley was home to six municipalities: Ayer, Chandolin, Grimentz, Saint-Jean, Saint-Luc and Vissoie. The citizens of those municipalities agreed on November 26, 2006, to merge into one, which was named Anniviers. The merger took place in January 2009.
The Illhorn is a mountain of the Swiss Pennine Alps, overlooking Chandolin in the canton of Valais. With a height of 2,717 metres above sea level, it is the highest point of the Illgraben valley.
Anniviers is a municipality in the district of Sierre in the canton of Valais in Switzerland. It was formed through the merger of six municipalities in Val d'Anniviers: Ayer, Chandolin, Grimentz, Saint-Jean, Saint-Luc and Vissoie. The merger became effective 1 January 2009, creating the third largest municipality of Switzerland by area.
A sediment gravity flow is one of several types of sediment transport mechanisms, of which most geologists recognize four principal processes. These flows are differentiated by their dominant sediment support mechanisms, which can be difficult to distinguish as flows can be in transition from one type to the next as they evolve downslope.
A major landslide occurred 4 miles (6.4 km) east of Oso, Washington, United States, on March 22, 2014, at 10:37 a.m. local time. A portion of an unstable hill collapsed, sending mud and debris to the south across the North Fork of the Stillaguamish River, engulfing a rural neighborhood, and covering an area of approximately 1 square mile (2.6 km2). Forty-three people were killed and 49 homes and other structures destroyed.
A series of mudflows occurred in Southern California in early January 2018, particularly affecting areas northwest of Montecito in Santa Barbara County. The incident was responsible for 23 deaths, although the body of one of the victims has never been found. Approximately 163 people were hospitalized with various injuries, including four in critical condition. The disaster occurred one month after a series of major wildfires. The conflagrations devastated steep slopes, which caused loss of vegetation and destabilization of the soil and greatly facilitated subsequent mudflows. The mudflows caused at least $177 million in property damage, and cost at least $7 million in emergency responses and another $43 million to clean up.
Beauregard Castle is a ruined castle on the territory of Chippis in the canton of Valais, Switzerland. It is situated on a rocky spur at the entrance to the Val d'Anniviers.
Lac de la Bayenna is a mountain lake in the Val de Moiry, a side valley of the Val d'Anniviers, on the territory of the municipality of Anniviers in the Swiss canton of Valais. It lies at 2,546 m (8,353 ft) west of Lac de Châteaupré above the glacier forelands of Moiry Glacier. Its outlet flows into the Gougra river after about 800 m slightly below Lac de Châteaupré.
The Pfynwald or Bois de Finges is a natural reserve and one of the largest continuous Scots pine forests of Europe. It is located on the language border between German- and French-speaking Valais, Switzerland, on the alluvial cone below the Illgraben valley.