Landslides are very common at foothill areas. So, we should not construct houses at the foothill areas.

North Northeast one : Gangetic plains covering the states of Punjab Haryana, Uttar Pradesh, North Bihar, West Bengal and Brahmaputra valley are the major flood prone areas of our country.
Other Regions : Coastal Andhra Pradesh, Odisha and Southern Gujarat

The waste that may or tend to cause adverse health effects on the ecosystem and human beings are called hazardous wastes
Ex. Pesticides, waste oil, nuclear power plants.

i) Hazard is defined as a thing, person, event or factor that poses a threat to people, structures or economic assets and which may cause a disaster.
ii) It could be either human-made or naturally occuring in the environment.

Water pollution is any chemical, physical or biological change in the quality of water. It has a harmful effect in human and aquatic life.
In India, water pollution has been taking place on a large scale and since a long period. Both surface and groundwater bodies are polluted to a great extent.
The major causes of water pollution are
i) Urbanisation
ii) Industrial effluents
iii) Sewages
iv) Agricultural runoff and improper agricultural practices
v) Seawater intrusion
vi) Solid wastes
Water pollution mainly affects the water based ecosystem. It also disrupts the natural food chain.

Earthquake is a violent tremor in the earth's crust, sending out a series of shock waves in all directions from its place of origin.
Effects of Earthquake
The primary effects of earthquakes are ground shaking, ground rupture, landslides, Tsunamis and leakage of gas (liquefaction).
Secondary effect
Fire is probably the single most important secondary effect of earthquakes.