Assertion (A): A tsunami is a large destructive ocean wave that can be generated by any disturbance that rapidly displaces a large mass of water.

Reason (R): The most common cause is an undersea earthquake.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

A series of shocks that result from sudden earth movement:

1. Earthquake
2. Volcanoes
3. Earthquake waves
4. Plate tectonics

Which waves are recorded on a seismograph after the P waves?

1. Primary waves
2. Push waves
3. Shear waves
4. Surface waves

Which of the following measures the power of an earthquake on a scale of 1 to 9?

1. Seismograph
2. Richter scale
3. Mercalli scale
4. Thermometer