According to Japanese myths, the cause of earthquakes is the giant catfish namedNamazu living buried in the underground. Namazu is one of the yo-kai (in a very broad sense translatable as “monster”) creatures of Japanese mythology and folklore that were associated with or caused misfortune or disasters.
By moving his tail Namazu can shake the entire earthand… and unfortunately he loves to cause trouble and havoc. Namazu can be controlled only be the god Kashima which, with the help of a powerful capstone, pushes the fish against the underground and in doing such immobilizes him. However the god sometimes gets tired or is distracted from his duty and Namazu can move a bit and cause an earthquake. The Great Ansei Earthquake of 1855 is said to have occurred when Kashima went out of town and left Ebisu (god of fishing and commerce) in charge.
Earthquakes were explained by movements of deities or creatures supporting the Japanese main islands, these creatures included gods, giants, an ox, dragons or snakes and a fish. Already in the Tokugawa period (1603-1868), the giant catfish was as a river deity associated to natural disasters, not surprisingly caused by water like floods or heavy rainfall. In these early traditions however, Namazu often acts as a premonition of danger, warning people from an imminent catastrophe or even swallowing the dangerous water-dragons to prevent disasters. The dragon was a very old and powerful symbol imported from China and was in old times the main culprit of earthquakes. However, during the 18th century, a giant Namazu gradually replaced the giant dragon in the popular imagination. This change was minor because dragons were also associated to water and rivers and so were closely related to the catfish in the popular imagination.
During the 19th century and after the earthquake of Edo in October 1855, the wrongdoings of Namazu became more a punishment of human greed. It was believed that the catfish by causing havoc forced people to redistribute equally their wealth, in this role Namazu became yonaoshi daimyojin, the “god of world rectification”.