Name the scale on which the magnitude of the earthquake is measured?
Richter scale.
What is a seismograph?
A seismograph is a machine which measures an earthquake.
Name the three types of earthquake waves.
P waves or longitudinal waves S waves or transverse waves L wave or surface waves.
Define focus’ and ‘epicentre’.
The place in the crust where the movement starts is called the ‘focus’. The place on the surface above the focus is called the ‘epicentre’.
What is a volcano?
A volcano is a vent or opening in the earth’s crust through which molten material erupts suddenly.
How do the lithospheric plates move?
They move around very slowly, just a few millimeters each year.
What do you know about the lithospheric plates?
The earth’s crust consists of several large and some small, rigid, irregularly— shaped plates, Le., slabs which cany continents and the ocean floor.
Find out the names of a few rivers of the world that form a delta?
Name of some rivers (See the Map): Mississippi—Missouri. Amazon. Parana—Paraguay. The Nile. Zaire. Tigris—Euphrates. Ganga—Brahmaputra. Indus. Hwang Ho. The Yangtze. Irrawaddy. Salwin. Murray—Darling.
Buildings collapse due to earthquakes because of the following reasons:
Most buildings are not built/made earthquake-proof. When the earthquakes strike, the buildings are not capable of resisting thevibrations of the earthquakes. They tear apart due to shallow foundation, sub-standard interior material, and lack of adequate steel. They collapse and fall down like a pack of papers/cards.