Explanation:

Only statements 1,2&3 are correct.

• An earthquake is the vibration/shaking experienced on surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves.

• The intensity of earthquake is measured on Mercalli Scale whereas the magnitude of an earthquake is a measured-on Richter Scale.

• The earthquake’s magnitude is determined using the logarithm of the amplitude of the largest seismic wave calibrated to a scale by a seismograph.

• Each increase of 1 unit on the scale represents a 10-fold increase in the magnitude of an earthquake.

• That is each integer reading of the Richter scale has an energy 100 times that of the previous integer reading

Hence option 3rd is correct.