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Natural hazards and disasters; Mitigation strategies.
1) EARTHQUAKES
An earthquake is shaking of earth's surface that happening because of sudden release of energy from earth's crust due to tectonic plates movement.
The lithosphere which is known as the earth's outer shell that divided into several large tectonic plate that float on top of partially molten layer called asthenosphere, these plates can stuck in their edges due to fraction, that causes sudden release of energy from earth's crust causes generation of seismic waves and a ground shaking.
Other names of earthquake are Quake, Tremor or Temblor.
Main causes of earthquake
1) Tectonic plate movements
2) Volcanic activities
3) Anthropogenic activities
FOCUS AND EPICENTER
The focus is the point where the earthquake is generates, it is the actual location in the earth's crust where the earthquake's energy is released. Focus is also called hypocenter.
The epicenter is the point just above the hypocenter on the earth's surface.
SEISMIC WAVES
Seismic waves are generated due to sudden movement of tectonic plate in earth's crust during earthquake. These are the energy waves that can travel through inside of the earth and on the surface. Seismic waves can classified as Body waves, Surface waves.
A)BODY WAVES
Body waves are originated at the epicenter and travel through the earth's interior. These waves are classified as primary and secondary waves.
1)P WAVES
P waves are primary or pressure waves, can travel in solid, liquid, and gases. These are the fastest seismic waves which travel in linear direction.
2)S WAVES
S waves are secondary or shear waves can travel only in solid. These are slower than p waves and travel in transversal direction.
B) SURFACE WAVES
Surface waves are those waves which are travel along the earth's surface. These are responsible for most of the damage caused by earthquake. Surface waves have two types
1) LOVE WAVES
Love waves move in a side-to-side, horizontal direction and are responsible for horizontal shaking of the earth.
2)RAYLEIGH WAVES
Rayleigh waves have a rolling direction, like ocean waves, and cause both vertical and horizontal ground movement.
Measurement of intensity of earthquake
1) RICHTER SCALE
Richter scale or Richter magnitude scale was developed by Charles F Richter in 1935. That used to measure the magnitude of the earthquake based on amplitude of seismic waves. It ranges from 1-10 which quantify the energy released during an earthquake.
2) MODIFIED MERCALLI SCALE
Modified mercalli scale was developed by Giusseppe mercalli to measure the intensity of earthquake in specific locations. It assess the effects of an earthquake on people, structure and earth's surface. Range of the scale is from 1 to 12.
Consequences of earthquake
1) Loss of human and animal life
2) Genaration of Tsunamis in coastal areas
3) Landslides and avalanches
4) Economic loss
Management or mitigation strategies
1) Introduce the earthquake resistant architecture for buildings
2) Observing animals behaviour
3) Implement the early warning system
4)Educate the public on earthquake and about how to Drop, Cover, and Hold On" during shaking.
2) TSUNAMI
Tsunami is a derived from Japanese term tsu means harbour and nami means waves so Tsunami is a harbour waves. It a natural disasters that can result from different environment factors such as earthquakes, volcanic eruptions, or underwater landslides etc.
This is caused by displacement large volumes of water in ocean creating powerful, long-period ocean waves that can travel across entire ocean basins happening from earthquake or volcanic eruption.
Mitigation strategies
1) Implement the early warning system.
2)Educate the people of coastal areas about Tsunami
3) Construct protective sea walls along coastlines to reduce wave impact.
3) VOLCANIC ERUPTION
A volcanic eruption is an eruption of molten rock, hot rocks, fragments, ashes, hot gases etc are come out from the earth surface through a vent. Volcanic eruption can causes the damage of life and loss to environment.
VOLCANIC VENT
Volcanic vent is the place on the earth's surface where magma, gases and other volcanic materials are come out during eruption.
MAGMA
Magma is a molten rocks found under the earth's surface consisting the complex mixture of liquid solid and gases. Magma is composition of liquid materials, corbon dioxide, sulphureted hydrogen and water vapour. Molten rocks which is come out of the earth is called lava.
MAGMA CHAMBER: It is located beneath the vent where magma is stored.
Mitigation strategies
1) Develop the volcano hazard maps to identify the areas at risks.
2)Educate the communities in volcanic hazard zones about eruption risks and emergency procedures.
3)To establish the early warning system to detect the volcanic activities.
4) LANDSLIDES
Landslide is a mass moment of the materials such as rocks, debris and download and outword of hill sloop that caused by heavy rainfall, earthquakes, mining, soil erosion etc. Landslides can resulting in significant loss of life Property and environment.
5) DROUGHTS
Droughts occurs due to absence or low rainfall for prolonged periods that can have a severe impact on ecosystem, agriculture, water supplies etc. Droughts doesn't have definite beginning and end, it can at start anytime and end at any time. Droughts can persist for months to years.
TYPES OF DROUGHTS
1)METEOROLOGICAL DROUGHT
Meteorological droughts occurs when there is a less than average rainfall happening for prolong period. It is concerned with the deficiency of precipitation over long period.
2) AGRICULTURE DROUGHT
Agricultural drought is because of lack of moisture content in soil, it affect on crop production and vegetation growth. It occurs when there is not enough moisture in soil to support plants growth.
3) HYDROLOGICAL DROUGHT
Hydrological drought occurs due to reduced rainfall on water sources like rivers, lakes, and groundwater. Hydrological droughts tends to show up more slowly because it involves stored water that is used but not replenished.
6) AVALANCHES
Avalanches are natural disasters caused by sudden, rapid flow of snow, ice, and debris down a mountain slope. They can be extremely dangerous and are influenced by various factors such as snowpack stability, weather conditions, and terrain.
7) CYCLONE
Cyclones are created in the region of low atmospheric pressure surrounded by high atmospheric pressure that causes the blowing of inward spiraling of wind in anti clockwise direction in northern hemisphere and clockwise direction in southern hemisphere.
8) WILDFIRE
Uncontrolled fires in forests or grasslands or other natural areas caused by lightning, strikes,and volcanic eruption etc.Wildfires can result in loss of life, destruction of homes and infrastructure, harm to ecosystems, and poor air quality due to smoke and particulate matter.
9) TORNADO
Tornadoes typically form in severe thunderstorms when certain atmospheric conditions are present. They develop when warm, moist air near the surface meets cooler, dry air aloft, creating instability. If strong wind currents in the atmosphere cause the air to rotate horizontally, a tornado can develop when this rotation is tilted vertically.
Tornadoes come in various shapes and sizes, but they are often characterized by a funnel-shaped cloud extending downward from a thunderstorm. The visible funnel can vary in width and may or may not touch the ground.
10)HEAT WAVES
Extended periods of excessively high temperatures, posing health risks and stressing infrastructure.
Effective disaster preparedness, response, and mitigation efforts are crucial to minimizing the impact of these natural hazards on human lives and communities. Additionally, climate change can exacerbate the frequency and severity of some of these events, making long-term planning and adaptation essential.
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