Photo/Illutration Downed Japanese cedar trees lean against electric wires in Sammu, Chiba Prefecture, on Sept. 18. (Hiromi Kumai)

SAMMU, Chiba Prefecture--The toppling of disease-ridden Japanese cedar trees here by Typhoon No. 15 that ravaged the prefecture earlier this month played a major factor in the widespread blackouts.

About 60 percent of households in the eastern Chiba Prefecture city, one-third of which is forest, suffered temporary power outages after scores of "Sanbusugi" cedar fell in the Sept. 9 windstorm, causing damage to electric wires and poles.

As a result, the blackout extended for 10 days or more in many areas.

While power supplies had fully resumed by Sept. 23, work to repair electric wires continued.

Many of the trees, a specialty of Sammu, fell in the strong winds because they had been left uncared for owing to a decline in the forestry industry, allowing a germ-related disease to spread among them.

Houses in the mountainous areas of the city receive power from electric wires running through forests, many of which were damaged by the toppled trees.

A total of up to 17,700 households, many located in mountainous areas, of the 29,600 households in Sammu suffered blackouts on the day the storm hit, according to TEPCO Power Grid Inc.'s Chiba regional branch.

The company confirmed at 12:47 a.m. on Sept. 21 that the electricity supply had resumed in all areas of the city.

Sanbusugi cedar has been planted in and around Sammu for more than 250 years. The cedars' trunks are straight and their diameter is similar at various parts of the same tree, making them ideal for use as lumber material.

However, the cedars easily contract a disease that causes decay in the outer part of the trunks.

After the typhoon passed, many ailing Sanbusugi trees were found to have been broken by storm winds at a height of around seven or eight meters.

As to why so many trees fell, an official at the Chiba Prefectural Forestry Research Institute said, "The biggest factor was gusts stronger than we've ever seen, with a maximum instantaneous wind speed of 180 kph."

The official added that the disease, which had spread in about 80 percent of Sanbusugi forests in Sammu, expanded the damage.

Few countermeasures have been taken to combat the disease, with as much as 95.7 percent of forests in Sammu privately owned as of 2017. Their owners hesitate to cut down or plant trees due to the high cost.

With regard to the widespread blackouts expanded by the toppled trees, Tatsuaki Kobayashi, a greenery environmental studies professor at Chiba University, said: "The price of Japanese cedar has been hovering at low levels, and privately owned forests have been left uncared for. Such a situation has continued for many years.

"It can be said that in Chiba Prefecture, where many communities are situated near forests, widespread blackouts were inevitable," he added.