A pair of megathrust earthquakes occurred off the coast on October 16 , 1737 , and on November 4 , 1952 , in the magnitude of ~ 9.3 and 8.2 respectively .
A pair of huge earthquakes occurred off the coast on October 16 , 1737 , and on November 4 , 1952 , in magnitudes ~ 9.3 and 8.2 respectively .