An earthquake has occured in Seattle, Washington and the distance from the epicenter to the recording station was found to be 300 km. The amplitude of the P-wave was found to be 20 mm and the amplitude of the S-wave was found to be 200 mm. Using the information below, what is the magnitude of the earthquake? a) 7.3 magnitude earthquake. b) 6.3 magnitude earthquake. c) 5.3 magnitude earthquake. d) 4.3 magnitude earthquake.