Tsunamis, Mass Wasting & Soil Erosion – Types and Effects

Key Concepts:

• Natural hazards
• Climate change
• Tsunami
• Mass wasting
• Soil Erosion

Introduction: 

Natural hazards are one of the main causes of concern on the Earth. About 40 billion US dollars per year, or 100 million dollars a day economic loss is caused by natural hazards. Globally, 100,000 people die every year due to natural hazards. Natural processes such as surface or internal processes that become a hazard have different causes and effects. In order to reduce the effects, it is essential to know the dynamics of the processes involved and to suggest the preventive measures that can be implemented within the socio-economic framework of the threatened area. There were around 755 natural hazard incidents in 1999. The majority deaths (98% of total) and damages of properties (93% of the total) mainly came from earthquakes, floods and windstorms. 

A natural hazard is a naturally occurring incident that has a negative impact on humans.   This negative impact is called a natural disaster. In other words, when a dangerous threat happens and destroys humans, that event is called a natural disaster. 

Natural hazards and subsequent disasters result from naturally happening processes that have worked throughout. A natural hazard is a threat as it has a negative effect on humans. In other words, when a hazardous threat takes place and harms humans, the incident is called a natural disaster. 

Natural hazards and subsequent disasters result from naturally occurring processes that have operated throughout the history of Earth. The most dangerous process is Geologic processes. 

Geologic processes affect human beings on the Earth, but they are most apparent when they cause loss of life or property. If the process that causes the hazard occurs and destroys human life or property, then a natural disaster has happened. Following are some of the natural hazards and possible disasters. 

Earthquakes, volcanic eruptions, tsunami, landslides, subsidence, floods, droughts, hurricanes, tornadoes, and asteroid impacts. 

Classification of Natural Hazards and Disasters 

Geophysical hazard: This hazard originates from solid Earth. For example: Earthquakes, landslides and volcanic activity. 

Hydrological hazard: This hazard is caused by the occurrence, movement and distribution of water on Earth. For example: Floods and avalanches 

Climatological hazard: This type of hazard is related to the climate. For example: Droughts and wildfires. 

Meteorological hazard: It is related to weather conditions. For example: Cyclones and storms. 

Biological hazard: It is caused by exposure to living organisms and their toxic substances or diseases they may have. For example: disease epidemics and insect/animal plagues. 

Man-made and technological hazards: These hazards are incidents that are caused by humans and occur in or close to human settlements. They consist of complex emergencies, disputes, industrial accidents, transport accidents, environmental degradation, contamination and pollution. For example: a flood causing from changes in the flow of river is a natural hazard, while flooding because of a dam failure is a manmade hazard, and hence omitted from the National Risk Index. 

Natural hazards can also cause secondary natural hazard consequences that produces additional hazards. For example, Volcanic Activity can create other hazards, like ash and lava spread. 

Earth’s process 

The Earth is a dynamic, developing system with intricate interaction of internal and external processes. The processes that shape and change the Earth can be largely categorised into “surface processes” and “internal processes”. 

Surface processes 

The more common heat source is the external heat of sun. Every day, the part of the sun’s radioactive heat is kept within the atmosphere. Because low latitudes get more heat than the high latitudes, and normal atmosphere temperatures decrease from the equator to the poles. So, change in heating, and the rotation of the Earth, makes air masses to move all around and makes our weather and climate. 

Mass Wasting 

Mass wasting is any downhill movement of  substances such as rock, sand, soil etc. caused by the gravity. The term landslide is generally used for mass wasting. Loose material along with overlying soils move during a mass-wasting event. Moving pieces of bedrock are known as rock topples, rock slides, or rock falls, based on the dominant movement of the blocks. Movements of more liquid material are known as flows. Movement by mass wasting [lanslides] can be slow or fast. Fast movement can be hazardous, such as in the course of garbage flows. Areas with steep structures and rapid rainfall, like California coast, Rocky Mountain Region, and Pacific Northwest, are especially prone to dangerous mass-wasting incidents. 

Tsunamis 

Tsunamis are water waves that are caused by rapid vertical movement of a large area of the sea floor during an undersea earthquake. Tsunamis are frequently called tidal waves. Unlike regular ocean tides, tsunamis are not triggered by the tidal action of the Moon and Sun. The height of a tsunami in the deep ocean is usually around 1 foot, but the distance between wave crests can be very long. It is more than 60 miles. The speed at which the tsunami travels decreases as the depth of the water decreases. In the mid-Pacific region, where the depth of the water reach 3 miles, the speed of tsunami can be more than 430 miles/hour. When tsunamis reach shallow water present all around islands or on a continental shelf. Many times,  the height of the waves increases and  sometimes it reaches almost 80 feet. The distance between wave crests inhibits tsunamis from dispersing energy as a breaking surf; instead, tsunamis cause water levels to rise rapidly along coast lines. 

Ground shaking due to tsunamis and earthquake vary in their destructive characteristics. Ground shaking causes destruction mostly in the surrounding area of the causative fault, but tsunamis affect damage both locally and at very distant locations from the area of tsunami generation. 

Soil Erosion 

Soil erosion is a slow process that occurs when the effect of water or wind detaches and removes soil particles, causing the soil to worsen. Deterioration of soil and low quality of water due to erosion and surface runoff have become serious problems through out the world. The problem may become so serious that the land can not be planted and needs to be abandoned. Many agricultural civilizations have dropped due to land and natural resource mismanagement.  

Effects of soil erosion 

The effects of soil erosion are mainly centered on reduced agricultural productivity and also quality of  soil. Sometimes water ways can also be clogged, and that can affect water quality. This means the majority of the environmental problems the world face today occurs due to soil erosion. The impacts of soil erosion consist of: 

1. Loss of Arable land 

Arable land defined as any land capable of being ploughed and used for growing crops. 

Soil erosion significantly affect lands that are used for crop production. Soil erosion washes away the fertile layer of soil called top soil and also the part that helps the soil’s important microorganisms and organic matter. In this way, soil erosion severely affects the efficiency of fertile cropping areas because they are constantly degraded. 

Due to soil erosion, the majority of the soil characteristics that help agriculture have been lost, this causes ecological collapse and mass starvation. It may happen that majority of the cultivated areas around the earth are exposed to soil erosion. 

2. Pollution of water and Clogging of Waterways 

Soils eroded from agricultural lands carry pesticides, heavy metals, and fertilizers and washed into rivers, streams and main water ways. This transport of various materials leads to the pollution of water and causes damage to  habitats of marine and freshwater ecosystem. Piled up sediments can also cause clog water ways and increases the water level leading to flooding. 

The water quality of various streams, rivers, and coastal areas get worse due to soil erosion, and ultimately affect the health of the local populations. 

3. Sedimentation and Threat to Aquatic Systems 

Apart from pollution of the water systems, high content of soil sedimentation can be dangerous to the survival of aquatic life. Silt can suffocate the breeding grounds of fish and also reduces their food supply. Due to this, the biodiversity of algal life and useful aquatic plants decreases. Sediments may also enter in the fish gills, and cause respiratory problems. 

4. Air Pollution 

Wind erosion collects dust particles of the soil and throws them into the air, this causes air pollution. Some of these dust particles may have harmful particles like petroleum and pesticides. When these harmful particles are  inhaled or ingested, they can cause a serious health issues. 

Due to the movement of wind, dust clouds from the deserts or dry areas can cause widespread air pollution. Such type of situation is evident in North America where dust winds from the Gobi desert have frequently been a significant problem. 

5. Damage of Infrastructure 

Soil erosion can cause damage to infrastructural plans like dams, drainages, and embankments. The deposition of soil sediments in dams, drainages and all along embankments can decrease their functioning and effectiveness. Also, the sediments that can support plant life can also cause cracks and damage the structures. if stabilizing techniques are not used  then soil erosion from surface water runoff generally causes significant damage to roads and tracks. 

6. Desertification 

Soil erosion is a major cause of desertification. It slowly converts a habitable land and the Arid and semi-Arid (ASAL) regions into deserts. The transformations are worsened by the damaging use of the land and deforestation that makes the soil accessible to erosion. This badly leads to loss of biodiversity, changes in ecosystems, degradation of land, and enormous economic losses. 

Summary

• Natural hazards are one of the main causes for concern on Earth.
• A natural hazard is a naturally occurring incident that has a negative impact on humans.
• Geologic processes affect human beings on the Earth, but they are most apparent when
  they cause loss of life or property.
• Earthquakes, volcanic eruptions, tsunami, landslides, subsidence, floods, droughts,
  hurricanes, tornadoes, and asteroid impacts are examples of natural hazards.
• The processes that shape and change the Earth can be categorised into “surface
  processes” and “internal processes.”
• Mass wasting is a any downhill movement of substances such as rock, sand, soil etc.
  caused by the gravity.
• ‘Tsunamis are water waves that are caused by rapid vertical movement of a large area of
  the sea floor during an undersea earthquake.
• Soil erosion is a slow process that occurs when the effect of water or wind detaches and
  removes soil particles, causing the soil to worsen.
• The effects of soil erosion are mainly centered on reduced agricultural productivity and
  also quality of soil.