Geological disasters. . .

Geological disaster refers to the geological action (phenomenon) formed under the action of natural or man-made factors, which causes damage and loss to human life, property and environment. Its main types are: landslide, collapse, debris flow, ground collapse, earthquake and so on.

Landslide: refers to the phenomenon that the rock mass on the slope slides down along a weak surface or weak zone under the action of gravity for some reason.

Collapse: refers to the geological phenomenon that the rock and soil mass on the steep slope suddenly breaks away from the parent body under the action of gravity and rolls and accumulates at the foot of the slope.

Debris flow: it is a unique natural phenomenon in mountainous areas. This is a special flood, because of precipitation, there are a lot of sediment, stones and other solid substances.

Ground collapse: refers to the natural phenomenon that surface rocks and soil fall downward under the action of natural or man-made factors, forming collapse pits on the ground.

Landslide precursor: 1, spring revival; 2. Soil uplift; 3. The sound of rock fracture or shear extrusion; 4. Collapse and relaxation; 5. The deformation is sudden; 6. The crack spreads rapidly; 7. Animals are extremely frightened and the normal growth of plants changes.

Debris flow identification: the ditch length in the middle reaches is asymmetric and uneven; Water falls in the groove; Form multi-level terraces, etc.

Precursors of ground collapse: abnormal changes of spring water and well water; Ground deformation; Buildings rattle, tilt and crack; Water accumulation on the ground causes bubbles, blisters and eddies on the ground; Plant metamorphosis; Animals are frightened.

Landslide, collapse and debris flow are not only different, but also closely related, transformed and inseparable.

Relationship between landslide and collapse

Landslides and collapses are twin sisters, even inseparable. They often go hand in hand, which are produced in the same geological and structural environment and under the same stratigraphic and lithologic structural conditions, and have the same trigger factors. Areas prone to landslides are also prone to collapse. For example, baoji-chengdu railway Baoji? Mianyang section is a frequent area of landslides and collapses. Collapse can be transformed into landslide: a place collapses continuously for a long time, and a large number of collapses and accumulations can produce landslides under certain conditions; Sometimes collapse is directly transformed into landslide movement in the process of movement, and this transformation is more common. Sometimes the gravity movement of rock and soil is between collapse and landslide, so that people can't tell whether this movement is collapse or landslide. So geologists say this kind of landslide, or landslide, can induce and transform each other under certain conditions: the landslide is shot down on the upper part of the old landslide or loose and unstable accumulation body, and sometimes the old landslide can be revived or a new landslide can be produced under the gravity impact of collapse. If the terrain suddenly becomes steep when the landslide slides downward, the sliding body will turn from sliding to falling, that is, the landslide will turn into collapse. Sometimes, because there are many cracks at the rear edge of the landslide, the high and steep rear wall will collapse continuously after the landslide. In addition, landslides and collapses have the same secondary disasters and similar precursors.

2. Relationship between landslide, collapse and debris flow

Landslide and collapse are also closely related to debris flow, and debris flow is also prone to occur in areas prone to landslide and collapse, but the outbreak of debris flow has indispensable water conditions. In addition, collapse and landslide materials are often important sources of debris flow solid materials. Landslides and collapses are often directly converted into debris flows during the movement, or after a period of landslides and collapses, under certain water conditions, debris flows are generated by their deposition. That is, debris flow is a secondary disaster of landslide and collapse. Debris flow, landslide and collapse have many similar triggering factors.

The factors affecting the formation of debris flow are very complicated. They include lithologic structure, topography, soil layer vegetation, hydrological conditions, climate and rainfall. Because debris flow is a fluid composed of mud, sand, stone and water moving along a certain gully bed, its formation must meet three conditions, namely, water body, solid debris and certain slope topography and gully, and all three are indispensable. Water mainly comes from rainstorm, reservoir burst and melting of ice and snow. Solid debris comes from mountain collapse, landslide, rock spalling, soil erosion, ancient debris flow accumulation and debris formed by human economic activities such as deforestation, mining and road construction. Its topographical condition is the slope and valley topography with large height difference and steep slope formed by long-term geological tectonic movement in nature.

That's about it.