Today’s Earthquake Fact
Human beings can detect sounds in the frequency range 20-20,000 Hertz. If a P-wave refracts out of the rock surface into the air, and has a frequency in the audible range, it will be heard as a rumble. Most earthquake waves have a frequency of less than 20 Hz, so the waves themselves are usually not heard. Most of the rumbling noise heard during an earthquake are from buildings (and their contents) moving.
Today in Earthquake History
December 8, 1976
M 5.2, South Africa – The earthquake was centered in the gold mining area of Welkom about 300 kilometers south of Johannesburg. Four people were killed, 36 injured and considerable… Read More