The number of classes of earthquakes based on magnitude of Ritcher scale are ______

What should be the type of foundation for concrete and masonry buildings?

The phase which involves restoration to state of equilibrium is ______

60 – 300 km focus distance is seen in which type of earthquake?

What do the rocks undergo during seismic shocks?

Which of the following need not be avoided for construction of quake resistant buildings?

The inner regions of plates are free from tectonic earthquakes.

The point vertically above the focus is ______