大阪には道頓堀という地名がある様に、江戸時代の大阪は幅が５０mもある堀川が東西に張り巡らされていた。人々は密集した民家の火事を恐れ、家財道具を堀川の舟に積んで非難する事が習慣だった。その習慣が津波の餌食になるという痛ましい教訓を残した。
ところがその２４９年前に実は同じ地震による津波で、多くの死者を出していたのである。これが宝永地震（１６０５年）である。安政南海地震後の大阪・大正橋の石碑には、舟に逃げて津波に襲われる事への教訓が、生かされなかった悔しさが刻まれている。
As there is a place called Dotonbori in Osaka and "bori" means moat, 50-meter-wide moats stretched east to west in Osaka in the Edo period. It was common practice for people to escape by boat on the moat with their household goods because they feared fire could occur in the built-up area. It taught them a harsh lesson that many became the prey of the tsunami.
However, a same tsunami caused by the earthquake actually had brought many deaths 249 years earlier. It had been Houei earthquake in 1605. The lesson learned from tsunami damage was not utilized due to escape by boats and the sorrow for the failed lesson is inscribed in the stone monument built after Ansei-Nankai earthquake alongside Taisho-bashi bridge in Osaka.
