Disaster Prevention / Disaster Risk Reduction Sites

Area AreaNomashi・MabushiNomashi・Mabushi

In the event of a major eruption, a lava conduit dike was constructed in Omiyasawa to redirect the flow of lava to protect the village of Nomashi, which is located downstream in the valley, in case the lava flow overflowed from the outer rim and flowed down the mountainside.

There are two ways to minimize the damage caused by lava flows: to stop the flow or to change the course of the flow. The weir at Omiyasawa was designed to divert the lava flow to the sea by bypassing the houses in Nomashi. The riverbed of the channel was excavated and the sediment was embanked on the village side. The 1,400m-long embankment, which was started in 1998, was scheduled to be completed in 2013.

In October of 2013, a typhoon hit the island, causing a massive landslide due to heavy rains. Although a slope collapse also occurred in Omiyasawa, sediment and driftwood flowed through this dike, which was effective in reducing damage to Nomashi.

Channel leading lava flow to the sea

Omiya Bridge

Location Information