There are many myths in the Kojiki and Nihonshoki. However, one class of myths is notable by their absence. There are no myths of great floods, or of the world being overturned in a great earthquake, or of a volcanic eruption. Even when we do get a myth about the kami cursing the population, the curse is an epidemic.
As with most absences, this is hard to notice, but once I did, it struck me as in need of explanation. If there was ever a country that you would expect to want a mythic explanation of floods, earthquakes, volcanos, and typhoons, it is Japan. But it seems that the early Japanese did not feel the same way.
Once you get out of the mythic bits of the early history texts, you do start to find records of this sort of natural disaster, and of prayers to the kami to prevent them. Indeed, prayers for sensible amounts of rain and moderate wind were a part of the standard ritual year of the Imperial court, and many jinja were established or honoured to pacify the kami of volcanos. But one does not see that in the myths.
The myths of Susano’o come closest. When he cries for his mummy, that makes all the trees die — and that is what salt water does to many species of trees, as we learned after the 2011 tsunami. When he climbs up to the heavens, he makes the ground shake. When Amaterasu Ōmikami hides from him in a cave, everything goes dark. And the story of him rescuing “Princess Marvellous Rice Field” from the eight-headed serpent Yamata-no-Orochi has been interpreted as a metaphor for the engineering works needed to stop seasonal flooding from washing wet rice fields away.
Nevertheless, none of these myths are about the natural disaster, and none of them are connected to natural disasters in general. Earthquakes are certainly not normally caused by Susano’o climbing up to the heavens, for example.
The most famous flood narratives arose in cultures that lived in near-desert areas, so one could argue that natural disasters are just too normal in Japan to form the centrepiece of a myth.
However, lots of cultures have myths to explain everyday occurrences. There are many myths explaining why the sun rises and sets, and that’s as everyday as it is possible to be. Japan does not seem to have myths like this either. Amaterasu Ōmikami may have been the sun, and we have eighth-century evidence that Tsukuyomi was the moon (the name is used for the moon in poems in an eighth-century poetry collection, the Man’yōshū), but there are not really any myths explaining why they rise and set.
While I find this interesting, I do not have an explanation. I can speculate. The obvious speculation is as follows. The Kojiki and Nihonshoki were not written to collect myths. They were written to legitimise the Tennō, particularly in the eyes of the Chinese. Thus, myths that the Chinese might think were primitive were left out. If they were not relevant to explaining why the Tennō should be in charge they disappeared completely, and if they were, they lost some elements.
It may be worth noting that the Miyakëki, a collection of myths about the Izu Peninsula in central Japan, does explain why there are volcanic eruptions on the islands: it is because Mishima Daimyōjin is making islands on which he can live. He is still building extensions to his house, and so eruptions still happen. These myths were collected for a different purpose, and so answer different questions.
But this is speculation. All I can really say is that Shinto myths seem to be answering fundamentally different questions from western myths. And is that really surprising?