Some earthquakes on San Andreas Fault triggered by gravitational tug of sun and moon...
"This phenomenon has fascinated scientists for years. Like sea levels, the surface of the Earth also goes up and down with the tides, flexing the crust and stressing the faults inside. Further study found that during certain phases of the tidal cycle, small tremors deep underground – known as low-frequency earthquakes – were more likely to occur."
On the morning of December 26, 2004 a magnitude 9.3 earthquake caused the Tsunami which struck Sumatra, killing 300,000.
It was during a full moon.
Edited by Rogerdodger, 18 July 2016 - 10:08 PM.