HIGASHI-MATSUSHIMA, Miyagi Prefecture--Erected nearly 100 years before the devastating 2011 tsunami, a memorial stone reminds residents of another destructive flood that occurred here during the Taisho Era (1912-1926).

The newly discovered monument stone found in high grass near the coast had been split in two likely in the tsunami spawned by the Great East Japan Earthquake on March 11, 2011.

Residents have started efforts to preserve “the message from the past that tells us not to forget about the earlier disaster.”

Measuring 70 centimeters long and 3 meters wide, the artifact, made of locally produced stone and bearing the title “Records on Tateishi Floodgate Refurbishment,” is believed to have initially stood on its base.

According to its inscription, the floodgate was set up to control agricultural water along the Tona waterway in the Nobiru district. The wooden equipment was repeatedly destroyed in flooding, inundating surrounding fields and paddies.

The floodgate was finally replaced with a strong stone made based on a prefectural subsidy due to efforts by the Nobiru mayor and others, according to the monument.

While the memorial was installed in November 1914, a rainstorm and high waves are said to have caused serious damage to the region in August the previous year.

The monument was discovered in spring 2017 by Seiko Matsukawa, 69, who surveyed the history of the local harbor construction. Matsukawa had been told of its existence by workers involved in disaster recovery on the former site of the historic Nobiru port, which dates to the Meiji Era (1868-1912), in the Hamaichi district across a river.

There are mysteries about the monument as the existence of the large artifact had not been known before the 2011 disaster. No mention of the stone can be found in local records, and why it was spotted 1 kilometer from the floodgate is unclear since the possibility of it being carried by the tsunami is low.

“The rebuilding of the floodgate was forgotten as time passed, and the monument may have been buried in the soil or used as the foundation in construction work and for other purposes,” said Matsukawa. “It could have been unearthed by the 2011 tsunami and carried to the site with other kinds of wreckage during debris removal operations.”

Another mystery is that after the memorial was discovered in 2017, it was encircled by a yellow-and-black rope, but its location became unknown as it was fully covered by grass.

In autumn 2019, Matsukawa looked for it again as the grass withered and "rediscovered" it. A residents' group and the Higashi-Matsushima city educational board removed the withered weeds, and an expert made a rubbed copy of the inscription at the time.

“We will take some measures to preserve or reinstall the artifact,” said an educational board representative.

Koki Goto, 68, a civil engineering researcher who heads the residents’ group and a great-grandson of the Nobiru mayor at the time of the stone’s erection whose name is engraved on it, noted that the discovery site used to be a marsh at the mouths of two rivers and has frequently been inundated.

“Our ancestors could benefit from the presence of the waters, but the stone monument indicates they were also struggling to tackle the issues of tsunami and flooding as well,” said Goto. “The discovery of the memorial may call on us to thoroughly rethink how the local community was formed and what kind of anti-disaster steps should be taken.”