Correct Option (a):
The Richter scale is a logarithmic scale. This implies that an increase of one unit in magnitude on the Richter scale corresponds to a tenfold increase (factor of 10) in the amplitude of the seismic waves recorded by a seismograph. Therefore, statement 1 is correct.
Incorrect Options:
Statement 2 is incorrect. While the Richter scale measures amplitude logarithmically, the energy released by an earthquake does not increase by a factor of 100 for each whole number increase in magnitude. Instead, each integer increase in magnitude on the Richter scale represents an approximate 32-fold increase in the energy released. This relationship is based on the fact that the energy release scales with amplitude to a power of approximately 1.5.
- Option (b) is incorrect because Statement 1 is correct.
- Option (c) is incorrect because Statement 2 is factually inaccurate.
- Option (d) is incorrect because Statement 1 is correct.