The Meiwa tsunami

The earthquake struck early in the morning. The wave that followed struck the southern and eastern coasts of Ishigaki hardest and swept far inland across the flat southern plain.

The death toll across the Yaeyamas and Miyako is generally put at around twelve thousand. Ishigaki’s population is thought to have fallen by roughly half, and some villages ceased to exist. It is, by proportion of population killed, among the worst natural disasters in Japanese history.

How high

Contemporary records claimed run-up heights of over eighty metres, and that figure circulated for two centuries. Modern geological work has revised it down substantially — the current scientific consensus puts the maximum run-up at around thirty metres, which is still catastrophic and still among the highest ever recorded in Japan.

Scattered across the island’s northern and eastern shores are the tsunami-ishi — coral boulders weighing hundreds of tonnes, carried inland by waves and left where the water dropped them.

The stones

The best known is the Tsunami Ufuishi, a coral block the size of a small house sitting in a field well back from the sea. Several of these boulders have been dated, and they record more than one event over the last several thousand years.

They are, in effect, a hazard map written in rock. Japanese tsunami research uses them, and they are the reason this island’s coastal geology is studied internationally.

And then it got worse

The aftermath was compounded by the poll tax, which the administration continued to levy on a population that had lost a third of its people and most of its farmland to salt. Famine and malaria followed, and the Yaeyamas did not recover their pre-1771 population for well over a century.

If you visit only the turquoise bay and the sand lanes, you will leave with an impression of these islands as uncomplicatedly beautiful. They are also a place that was nearly emptied within living memory of its own oral tradition.