What is the wavelength of an earthquake wave if it has a speed of 6 km/s and a frequency of 13 hz?

Velocity can be calculated using the following rule:
velocity = lambda * frequency where:
velocity is given = 6 km/sec
lambda is the wavelength that we want to calculate
frequency is given = 13 Hz

Substitute with the givens in the above equation to get the wavelength (lambda) as follows:
6 = 13*lambda
wavelength = 6/13 = 0.461538 Km = 461.538 meters