Jawaban:

Intensity of an earthquake P wave is a measure of the energy that is transmitted through the Earth by the wave. It is usually expressed in units of watts per square meter (W/m^2). The intensity of an earthquake P wave decreases with distance from the source, meaning that the intensity of the wave will be lower if it is detected further away from the source.

To calculate the intensity of the earthquake P wave if it is detected 400 km from the source, we can use the inverse square law, which states that the intensity of a wave decreases inversely with the square of the distance from the source.

If the intensity of the earthquake P wave is 1.0 x 10^-7 W/m^2 when it is detected 100 km from the source, and the distance from the source is increased by a factor of 4 (from 100 km to 400 km), the intensity of the wave will decrease by a factor of 4^2 = 16.

Therefore, the intensity of the earthquake P wave if it is detected 400 km from the source will be 1.0 x 10^-7 W/m^2 / 16 = 6.25 x 10^-9 W/m^2.