Both of the blocs knew the consequences of war would be great loss no matter you won or lose the battle. They would not like to risk the safety of nation and are trying to recover from WWII as well as trying to expand their economy, therefore avoiding direct military conflict at all cost.
It is also because that they have developed military weapons and once military force is involved, nuclear weapons might be used and cause a devastatingly large scale destruction which neither wanted to happen.
According to National Geographic, the maximum displacement along the fault between the two tectonic plates during the magnitude 9 earthquake in Japan was 164 feet (50 meters).
