1. What is a geological disaster?

Geological hazards refer to geological-related disasters caused by natural factors or human activities, such as mountain collapse, landslides, mudslides, and ground collapses that endanger people's lives and property.

2. What kind of harm will be caused by geological disasters?

Geological disasters cause serious harm to the national economic construction and people's lives and property. For example, in the Xiaojiang River Basin in Yunnan, serious mudslides occurred 25 times in the past 40 years, causing 163 deaths and 55 serious injuries. The direct economic loss was 69.06 million yuan. On September 23, 1991, the landslide occurred in the head of Dazhaigou, Zhaotong City, Yunnan Province, with a total volume of 18 million m 3 , resulting in 216 deaths. In 1989, landslide-type mudslides in Xikou Town, Huaying, Sichuan Province killed 221 people.

3. What are the levels of geological disasters?

According to the degree of damage and the size of the scale, it is divided into four categories: large-scale, large-scale, medium-sized, small-scale geological disasters and geological disasters:

Extraordinary geological disasters: Due to the threat of disasters, it is necessary to relocate more than 1,000 people or potentially cause economic losses of more than 100 million yuan. Extraordinary geological disasters: geological disasters caused by more than 30 deaths due to disasters or direct economic losses of more than 10 million yuan due to disasters.

Large-scale geological disasters: Due to the threat of disasters, the number of people who need to be relocated and transferred is more than 500 people, less than 1,000 people, or geological disasters with potential economic losses of more than 50 million yuan and less than 100 million yuan. Large-scale geological disasters: more than 10 people and 30 people died due to disasters, or geological disasters caused by direct economic losses of more than 5 million yuan and less than 10 million yuan due to disasters.

Medium-sized geological disasters: Due to the threat of disasters, the number of people who need to be relocated and transferred is more than 100 people, less than 500 people, or geological disasters with potential economic losses of more than 5 million yuan and less than 50 million yuan. Medium-sized geological disasters: more than 3 people and 10 people died due to disasters, or geological disasters caused by direct economic losses of more than 1 million yuan and less than 5 million yuan due to disasters.

Small geological disasters: Due to the threat of disasters, the number of people who need to move and relocate is below 100, or the potential economic loss is less than 5 million yuan. Small-scale geological disasters: less than 3 people died due to disasters, or geological disasters with direct economic losses of less than 1 million yuan due to disasters.

4. What is the collapse?

Collapse refers to the rock mass on the steep slope. Under the action of gravity, it suddenly falls off the mother body and dumps downwards. The geological phenomenon accumulated in the slope (or valley) generally occurs when the slope of the terrain is greater than 50 degrees and the height is greater than 30 meters. On the high steep slope.

5. What is a landslide?

Landslide (also known as walking mountain) refers to the geological phenomenon of rock and soil on the slope, sliding along a certain weak or weak zone under the action of gravity, sliding down integrally or dispersedly. The landslide mostly occurs when the slope is less than 50. Degree on the slope.

6. What is the debris flow?

Debris flow (also known as 蛟龙) is a natural geological phenomenon unique to mountainous areas. It is a special torrent that is excited by rainwater, ice and snow, etc., and contains a large number of mudstones. The debris flow is divided into mudslides and muds according to the composition of the material. There are three types of flow and water flow, which can be divided into viscous and dilute debris flows according to fluid properties; in addition, they are divided according to water source types; rainfall, glaciers and dam-breaking types; gully type and slope type according to topographical form. Water is an important part of the debris flow, and it is the excitation condition and transportation medium of the debris flow. Rain, snow melt and reservoir collapse can be a source of debris flow.

7. What is the ground collapse?

Ground collapse refers to a geological phenomenon in which surface rocks and soils fall down under the influence of gravity factors and form collapse pits (holes) on the ground.

8. What are the main causes of collapse and landslides?

The lithology of the slope is the material basis for the occurrence of landslides. The lithology of the strata is different, their strengths are different, and the degree of difficulty in landslides is different. Granite, quartzite, limestone rock massive, hard, dense, high shear strength, they are composed entirely of the slope, very few landslides, while the presence of weak shale, shale, coal, and the various surface layers of the cover layer Slopes are prone to landslides.

The mining is not in accordance with the specifications, and there are few reserved pillars, which are indiscriminately excavated, causing the goaf to collapse, causing the mountain to crack, and then collapse and landslide.

Construction of railways, highways, mountain building, construction and other projects, excavation toe, form an artificial steep slope, can lead to collapse, landslide.

A large number of buildings, factories, piles and piles are built on the slopes to increase the load on the slopes. The slopes cannot support excessive weight, and they lose balance and collapse and landslide.

Unsuitable land reclamation, deforestation, and destruction of vegetation are conducive to the infiltration of surface water such as rainwater into the ground, softening the rock and soil, and can also induce collapse and landslides.

9. Characteristics and activity characteristics of debris flow

The typical debris flow is divided into three zones: formation, circulation, and accumulation. The valleys also have three different forms.

The larger the longitudinal slope of the ditch bed, the more favorable the occurrence of debris flow, but the highest frequency of occurrence is 10-30%. Therefore, debris flows generally occur in mountainous areas, and their duration is very short, usually only a few minutes to tens of minutes. Their activities are characterized by high speed, sudden, periodic resurrection, chain and mass, and their destruction methods are buried and rushed. Destroy, block the river to block water and bend the road to climb high, super high hazard (such as 1979 Sichuan Ya'an, 1984 Yunnan Dongchuan mudslide deaths each more than 100 people).

10. Major hazards of collapse, landslides, and debris flows

The main hazards of collapse, landslides and mudslides are: destruction of land, houses, roads, bridges, and loss of people's lives and property. As of 1979, 100 kilometers of rock slope Jinhua-Wenzhou Railway collapse, causing four carriages derailed passenger train. In Ruojiadi Village, Luodong Township, Yongjia County, due to the typhoon storm No. 9909, it caused landslides and destroyed 42 houses, causing 17 deaths.

11. Types and characteristics of ground collapse

Ground collapse can be divided into mining subsidence and karst collapse according to its causes, while the latter has wide distribution, large quantity, high frequency, many induced factors, and strong concealment and sudden characteristics. Karst collapse can be divided into natural rock collapse and artificial karst collapse according to its genesis. Among them, the causes of natural karst collapse include heavy rain, flood, gravity, earthquake, anthropogenic karst collapse, cause drainage or water inrush, and extract karst groundwater. The reservoirs are mainly water diversion, accounting for 92% of the artificial collapse. The city is dominated by mining and subsidence, mainly distributed in coal mining areas.

12. What are the precursors of geological disasters?

The premise of the collapse is: the leading edge of the collapse continues to fall off, fall, and collapse; the new broken ruptures appear in the collapsed foot; occasionally the rock tearing sound is heard; the heat, gas and groundwater are abnormal Animals are abnormal.

The landslide precursors are: lateral and longitudinal cracks in the front edge of the landslide, and uplifting of the leading edge soil; the cracks at the trailing edge of the sliding body are sharply widened and lengthened, new cracks are continuously generated, the rear part of the landslide body is quickly lowered, and the surrounding rock and soil bodies are loose. And small collapse phenomenon; the landslide rock soil sounds due to frictional displacement, and gas or water emerges from the crack; at the slope front of the landslide, there is a blocked spring water resurrection or spring water, well water suddenly dry; animal There was an alarming anomaly; the observation point on the landslide body was obviously displaced; the drum sill appeared on the front edge of the landslide; the house was tilted, cracked, and the drunken forest and saber tree appeared.

The precursors of the debris flow are: there is a roar in the ditch, the main river water rises and the normal flow suddenly breaks. Animal and plant abnormalities, such as pigs, dogs, cattle, sheep, chickens, panic, unsleep, mice smashing, changes in plant morphology, forest wilting or skewing;

If some of the above symptoms are found, especially if cracks appear in the mountain, there may be hidden dangers of collapse and landslide. Long-term rainfall or heavy rain may induce mudslides.

13. How should geological disasters be used for emergency avoidance?

Avoid disaster victims and disasters. It is divided into active and passive situations, which refers to active avoidance and passive evacuation. For the projects and personnel in the danger zone, the methods adopted are: prevention, avoidance, evacuation, and governance. Each of these four links contains a large chance of disaster prevention and mitigation.

The emergency prevention measures for collapse and landslide disasters are: evacuate personnel and materials in a dangerous area in a timely manner according to the situation of danger; timely stop the driving force of the disaster; if there is any harbinger in advance, the evacuation plan should be formulated as soon as possible.

Do not run away from mudslides and run downstream. You should run on both sides of the ditch, but do not stay on the concave slope.

14. Basic methods for prevention and control of geological disasters

The basic methods of collapse and landslide prevention are mainly various reinforcement projects such as supporting, anchoring, load shedding, solidification, etc., and various drainage (surface drainage, underground drainage) projects are attached. The simple control method is to fill the landslide body with clay . Crack on the ground or repair the drain.

The basic method for prevention and control of debris flow disasters is to set up a perfect drainage system during engineering design and construction to avoid surface water infiltration and to fill the existing collapse pits to prevent surface water injection.

15. How should geological disasters be reported?

Units and individuals that discover geological disasters or disasters shall immediately report to the local people's government or the competent land and resources department. If other departments or grassroots mass organizations receive reports, they should immediately report them to the local people's government or the competent land and resources department.

Geological disasters can be roughly classified into the following categories:

Geological hazard species

The hazards of geological disasters to human beings are mainly manifested as: damage to settlements, geological disasters, especially landslides and mudslides rushing into villages, towns, flooding uninhabited animals, destroying land, and even causing disasters in villages. Harmful geological disasters on roads and railways, especially collapses and mudslides, can directly bury stations, railways, highways, destroy roadbeds, bridges and culverts, etc., causing traffic disruptions, and can also cause disruption of running trains and cars, causing major casualties. thing.

Therefore, the monitoring of emergency and slow-change geological disasters for sudden geological disasters is particularly important, and low-altitude remote sensing can play an increasingly important role in the field of geological disasters.

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