（解説文要約）
坑口近くに、砂利や火山灰でできた層があると、

大雨の時には雨がしみこみ、土砂が流れ出て坑道を塞ぐことがありました。
それを防ぐためには、描かれているように、直径7センチほどの杭（くい）を隙間なく打込んでいきます。この杭を「ナルギ」、または「セリギ」と呼んでいました。
土砂が流れ出したら採炭中止になってしまうので、

大慌てでベテランのシクリカタが取り掛かっていたようです。

 

 

During times of heavy rainfall, pits that were dug in places that consisted of gravel or volcanic ash would often have problems of soil and sand erosion causing blockage of the drives. 
To avoid this, miners would drive stakes into the ceiling lining tightly in a row to prevent earth and sand from running into the pit.

These stakes were only about 7 centimeters in diameter. They were known as Narugi or Serigi.
All work for mining coal ceased when soil erosion occurred and skilled repairmen had to rush in to do this construction.