Natural Calamities - Class 5 Notes & Olympiad Questions

Natural Calamities

a) Natural calamities, also known as natural disasters, are occurrences in nature that can cause harm to both living beings and property on Earth.
b) These calamities often result in alterations to the shape of the land and water bodies.
c) They are often triggered by significant shifts in climate and weather conditions.
d) Examples of such disasters include earthquakes, volcanoes, droughts, forest fires, tsunamis, cyclones, and floods.

Earthquakes

a) Earthquakes occur when there are internal changes or disturbances in the Earth's crust, resulting in the shaking of the ground. These tremors can be so powerful that they lead to the collapse of tall buildings, bridges, and other structures. The scientific field that studies earthquakes is called seismology.
b) The epicentre refers to the point on the Earth's surface directly above the location where the Earth's crust ruptures during an earthquake.
c) To measure the intensity of an earthquake at the epicentre, the Richter scale is used, which ranges from 1 to 10. Earthquakes with a magnitude beyond 3.5 on the Richter scale are typically felt by people. However, those that exceed 7 on the scale are considered to be devastating and massive.
d) The impact of earthquakes can cause significant damage and destruction to both life and property. Structures such as bridges and dams may collapse, and there can be additional harmful effects like landslides, flash floods, and forest fires.
e) Earthquakes also cause deformations on the Earth's surface. Underwater earthquakes can result in tsunamis and large tidal waves.
f) In the event of an earthquake, it is advisable to move outside into the open. It is important not to enter any buildings after an earthquake. If inside a building during an earthquake, taking shelter under heavy furniture or tables can help protect the head from potential falling objects.

Volcanic Eruptions

a) Volcanoes are openings or ruptures in the Earth's crust through which molten rock or magma flows out. Magma, which is a molten rock inside the Earth, is referred to as lava when it reaches the Earth's surface.
b) The volcanic eruption refers to the release of ash, lava, and gases from these openings.
c) Volcanoes are typically found on elevated landforms known as volcanic mountains.

Droughts

a) Droughts are long periods of low rainfall, resulting in a scarcity of water. They can occur due to changes in weather patterns, climate conditions, or human activities.
b) During a drought, the lack of water affects plants, animals, and people. It has severe consequences for agriculture, leading to reduced crop yields and food shortages.
c) Droughts also harm the natural environment, causing rivers and lakes to dry up, affecting aquatic life and increasing the risk of wildfires.
d) People may face water shortages for daily needs, and industries relying on water can be affected.
e) To cope with droughts, water conservation practices and management strategies are important. It is crucial to understand and prepare for droughts to minimize their impact and ensure sustainable water use.

Forest Fires

a) Forest fires are large, uncontrolled fires that happen in wooded areas. They can start from a small spark and quickly spread through the trees and plants.
b) Forest fires can be caused by things like lightning, campfires that aren't put out properly, or even people accidentally starting them. These fires can be very dangerous because they burn everything in their path, including trees, plants, and sometimes even homes.
c) They can harm animals and make the air smoky and hard to breathe.

Tsunamis

a) Tsunamis are typically triggered by underwater earthquakes, volcanic eruptions, or landslides that displace a significant amount of water. Tsunamis can also be generated by nuclear explosions.
b) These events result in the formation of enormous waves, which can reach heights of over 30 meters.
c) When these massive waves crash onto the shore, they cause widespread destruction.
d) Tsunamis can travel long distances, reaching coastal areas even thousands of kilometres away.
e) Coastal life and property are severely impacted by tsunamis.

Cyclones

a) Cyclones are very strong winds that spin in a circle around an area in the sky where the air pressure is low. They are formed due to the creation of low-pressure zones above seas.
b) Cyclones bring heavy rainfall and strong winds, causing extensive destruction.
c) Cyclones usually spin in a clockwise direction.
d) In the Atlantic Ocean and the Northern Pacific Ocean, cyclones are known as hurricanes.
e) The strong winds associated with cyclones carry water onto land, resulting in damage to life, property, and the natural environment.

Floods

a) Floods happen when there is too much water in an area and it overflows onto the land.
b) This can be caused by heavy rain, melting snow, or rivers and lakes that get too full.
c) They can damage homes, roads, and crops. Sometimes, people and animals can get swept away by the fast-moving water, so it's important to be safe and move to higher ground if there's a flood.